Archive for the ‘Abiotic stress’ Category

With Xsect Xtra, Inveragro eliminates pepper pests

Inveragro, located in the valley of San Felipe, Guanajuato, and known for its tradition of producing and drying chili peppers, was having problems with pest control and humidity levels inside the greenhouse. With Xsect Xtra, they were able to reduce the entry of thrips by 50% while increasing their humidity by 15%, resulting in an ideal climate that promotes pepper growth.

Inveragro is a 10-hectare pepper greenhouse that started operations three years ago in the valley of San Felipe, Guanajuato, an area with different challenges for pepper growers due to its semi-arid climate and the presence of insects and pests such as whitefly, thrips, and weevils.

Germán Sandoval Barba, grower at Inveragro, was looking for a climate solution that would help him face these challenges. A year ago, he decided to try Xsect Xtra.

Ideal humid climate = healthier peppers
The pepper is a tropical crop that likes high humidity levels. Ideally the humidity inside a pepper greenhouse should be between 60% and 80%.

During the summer months, humidity inside Inveragro was between 45% and 50%, and it was necessary to keep the windows closed as a way to conserve humidity inside the greenhouse.

“Before installing Svensson’s insect control nets, I was worried that the temperature would rise too much and that it would affect the humidity. Once we tested the nets, the truth is that it was a very positive surprise the results that we had in terms of temperature and humidity”, says Germán Sandoval

Unlike last year when the windows were practically closed, now with Xsect Xtra, the windows are open between 20% and 30%, having a maximum temperature between 32 and 33 degrees. In addition, with Xsect Xtra, the humidity inside the greenhouse increased between 10% and 15%, compared to last year, achieving an ideal humidity between 60% and 75%, which benefits the growth of peppers.

“I thought that I was going to experience disadvantages with this insect control net because, for me, it was more important to sacrifice climate in order to reduce the entry of pests and insects. But to my surprise, I now have a better climate and fewer insects inside the greenhouse,” said Germán Sandoval.

Greenhouses with 50% fewer thrips
One of the biggest challenges for Germán is the entry of pests, and one way to control this problem is through hermeticity. Inveragro has four full-time employees dedicated exclusively to supervising any failure in the hermeticity of the greenhouses. “When I started looking for options to improve our hermeticity, I discovered the Svensson insect control nets, which would help us to improve our conditions,” says Germán Sandoval.

Before installing Xsect Xtra, during the fifth week of the production cycle, thrips were already seen inside the greenhouse, and it was necessary to apply pesticides and/or agrochemicals prior to the release of the biological control. “Now I can release the biological control we use Orius to control thrips, without pesticides and/or agrochemicals applications that could damage the biological control program,” says Germán, “since the installation of Xsect Xtra, 50% fewer thrips have entered the greenhouse”.

Powdery mildew was another climate problem at Inveragro, and it was necessary to apply agrochemicals at least once a week. During the first year with Svensson’s insect control net, Germán continued with the same program, but no powdery mildew was found inside the greenhouse.

“I’ve already modified my program for this year. I’m only going to apply preventive products every 15 days, which reduces by 50% the cost of powdery mildew throughout the year because now I have better climate conditions in terms of humidity, which is more controllable and promotes pepper growth”.

Germán has also noticed improvements in the beneficial program used to control thrips. He used to have 4 Orius per square meter, and this year he only has three orius per square meter, which means savings in this year’s beneficials budget.

“What Xsect Xtra has given me is improved humidity, fewer pests, and reduced phytosanitary diseases.”
Finally, Germán shared the following advice for all pepper growers: “I would tell growers who are afraid to try these nets not to be afraid. In the beginning, I hesitated, but it is something that will help them. What it can generate in the climate is minimal and what it can help them in the phytosanitary issue is very broad. The net pays for itself”.

For more information:
Ludvig Svensson

info@ludvigsvensson.com www.ludvigsvensson.com    

Publication date: Mon 14 Nov 2022

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“Air pollution threatens natural pest control”

When fields of oilseed rape are exposed to diesel exhaust and/or ozone – both found in emissions from diesel-burning vehicles and industry – the number of parasitic insects available to control aphids drops significantly, according to research published today.

The team, led by scientists from the University of Reading, used special equipment to deliver controlled amounts of diesel exhaust and ozone to oilseed rape plants. They also added aphids to the plants and measured the reproductive success of parasitic wasps that habitually lay their eggs inside a freshly stung aphid.

Dr. James Ryalls, University of Reading said: “Even at the levels we used, which were lower than safe maximums set by environmental regulators, the overall numbers of parasitic insects still fell. This is a worrying result as many sustainable farming practices rely on natural pest control to keep aphids and other unwelcome creatures away from valuable crops.

Parasitic wasp and aphid – Peter Swatton, Rothamsted Research 

“Diesel and ozone appear to make it more difficult for the wasps to find aphids to prey upon and so the wasp population would drop over time.”

While the majority of parasitic wasp species decreased in polluted environments, one species of parasitic wasp appeared to do better when both diesel and ozone were present. However, the researchers found that this combination of pollutants also correlated with changes in the plants which might explain the finding.

With both pollutants present, oilseed rape plants produced more of the compounds that give brassica family crops, including mustards and cabbages, their distinctive bitter, hot, and peppery flavor notes. These usually repel insects but in the case of Diaretiella rapae wasps, there was greater abundance and reproductive success associated with diesel exhaust and ozone together.

Dr Ryalls said: “Diaretiella rapae particularly likes to prey on cabbage aphids, which love to eat brassica crops.

“We know that some of the flavor and smell compounds in oilseed rape are converted into substances that do attract D.rapae. So, we could speculate that the stronger smell attracts the wasps and they are more successful in finding and preying upon aphids, that way. It could be that D.rapae is a good choice for pest control in diesel and ozone polluted areas.

“This really goes to show that the only way to predict and mitigate the impacts of air pollutants is to study whole systems.”

As transport shifts away from diesel and towards electric motors, air pollution will change. Knowing how pest-regulation service providers, such as parasitic wasps, respond to these progressive changes, will be essential to planning mitigation strategies to ensure sustainable food security now, and in the future. This research shows that we also must consider the impact of pollution on the plants, wasps, and prey insects, and the interactions between all three.

For more information:
University of Reading

Publication date: Thu 10 Nov 2022

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New Meta-Analysis Examines How Landscape Fire Smoke Affects Insects


Research has found a variety of impacts on insects, both positive and negative, caused by smoke from wildfires and prescribed burns, but a new review of past studies shows we have much to learn. (Photo by Sebastian Werner via FlickrCC BY 2.0)

By Laura Kraft, Ph.D.

Laura Kraft, Ph.D.

During the 2019-2020 bush fire in Australia, some entomologists wanted to calculate the area burned and the total number of insects that may have been killed during the blaze. While those calculations were based solely on the charred acres, a new research review published in September in Environmental Entomology attempts to map previous research on how landscape fire smoke, including smoke from bush fires like the one in Australia, affect insects—and where gaps lie in knowledge that new research could fill.

Yanan Liu, a Ph.D. student in geography at King’s College London, led the study. She and colleagues first searched through more than 9,000 articles that linked to their search terms related to smoke. After carefully parsing through the literature and removing articles on smoke from sources like cigarettes or vehicles, the team ended up with 42 total publications focused only on landscape fire smoke, which includes wildfires, prescribed burns, and agricultural residue burns. The selected studies spanned 15 different countries.

Yanan Liu

The papers represented show an inordinate amount of research that tracks how smoke affects beetles, with fewer papers focusing on effects on flies, bees, and butterflies. And, Liu’s team found, the general consensus is that there is no general consensus. Landscape fire smoke both positively and negatively affects insects in a variety of different ways. Says Liu, “I expected the smoke to repel all the insects or have a negative effect, but it depends on the insect order. For example, beetles are actually attracted [to landscape-based fire].”

For some of those beetles, though, including the red flour beetle (Tribolium castaneum) and the rice weevil (Sitophilus oryzae), smoke produced from burning cow dung and neem leaves caused high mortality. Smoke produced from rice paddy burning with high carbon dioxide levels at 5,000 parts per million may have also caused 50 percent mortality in the rice weevil and the lesser grain borer (Rhyzopertha dominica) in one study.

When it doesn’t cause death, particulate matter in smoke appears to block the antennal receptors in some insects, including bees. While European honey bees (Apis mellifera) famously show signs of decreased aggression in response to smoke (which is why beekeepers have long used smoke to work in hives), other stinging species, like the Sonoran bumble bee (Bombus pensylvanicus sonorous) and the western yellowjacket (Vespula pensylvanica), also show a dramatic reduction in attacks due to smoke. “We normally use smoke to repel bees if you want to get honey from the bees’ home … and when you use a smoker, the bees fly away from their nest. If this smoke influences some insects and changes their behavior, maybe smoke from the landscape fire or from wildfire changes the behavior of other insects,” says Liu.

There are some signs that landscape fire smoke may affect insect flight and migration. Some butterflies initiate flight in response to savanna fires, and painted lady butterflies (Vanessa cardui) show decreased flight performance when subjected to smoke. Other insects have been shown to delay their flights until sky conditions are clear, which may be due to smoke affecting the polarization of light that the insects would typically follow.

Some insects benefit from landscape fire smoke and are attracted to it. This includes wood-burrowing beetles from insect families Cerambycidae and Buprestidae. Some species of these beetles are attracted to smoke and rush back to damaged trees to reproduce at higher rates and colonize the newly damaged trees.

In addition, black army cutworm moths (Actebia fennica) doubled the amount of eggs they laid in response to the volatiles produced from burning vegetation due to increased reproductive hormones. And they weren’t the only butterflies to benefit. During severe forest fires in Borneo in 1997and 1998, most insect species declined, except the butterfly Jamides celeno (family: Lycaenidae) that increased its abundance out of all butterflies in the region from just 5 percent to 50 percent of the assemblage.

Of the 38 studies that examined landscape-fire smoke impacts on insects included in a new research review in Environmental Entomology (and which were associated with individual countries), more than half (20) looked at fire in the United States or Canada. (Number of studies and number of insect species per country noted in parentheses.) (Image originally published in Liu et al 2022, Environmental Entomology)

Despite having publications from five of the seven continents, one of the trends that the researchers found was a clear bias toward papers from the United States and Canada, with a moderate amount from Australia and far fewer stretched out over developing countries in Africa and Asia. While Western readers are familiar with many wildfires in those regions that hit major news outlets, Liu’s team points out that average levels of particulate matter—the small, often toxic particles making up smoke—are often even more highly concentrated in other regions; a study published last year identified central and west Africa and south and southeast Asia as regions most affected by landscape fire smoke globally. Clearly, there is need to increase research studying how landscape fire smoke affects insect populations in these understudied regions.

These few examples of how landscape smoke dramatically affects some insect populations, both positively and negatively, show that more research is needed to expand our understanding of the effects of landscape fire smoke—for a wider diversity of insects, in a broader range of behaviors, and over a larger geographic area.

In the meantime, Liu and her colleagues are now chipping away at some of these questions by studying how smoke affects painted lady butterfly flight behavior.

Read More

Systematic Mapping and Review of Landscape Fire Smoke (LFS) Exposure Impacts on Insects

Environmental Entomology

Laura Kraft, Ph.D., is an entomologist, science communicator, and world traveler currently based in Orlando, Florida. Email: laurajkraft@gmail.com.


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Heightened weed burden could mean growers need to replace inundated crops

24 Oct 2022


Frontdesk / Arable

As a result of the summer’s prolonged drought, some early-drilled winter wheats are facing a heightened weed burden after the dry conditions have prevented pre-emergence herbicides from working effectively. That’s according to Mike Thornton, head of crop production for agronomy firm ProCam, who urges growers to assess affected fields to determine if the current crop should be retained or sprayed off and re-drilled.

 “Despite being a distant memory, the summer’s dry and hot conditions are still having an effect on the new cycle of cereal crops,” Mr Thornton explains. “Some wheats which were drilled ahead of schedule or on lighter land have suffered from a lack of soil moisture, which has prevented soil-acting pre-emergence herbicides from working to the best of their ability. As a result, some winter cereals are currently facing heightened competition from out-of-control weeds which, in the most severe cases, could threaten the crop’s viability and profitability.”

 Mr Thornton therefore recommends that each field should be assessed on a case-by-case basis to decide if the current crop, or part of it, should be sprayed off and re-drilled, either with a replacement winter crop, or with a subsequent spring crop.

 “Where the weed burden is excessive or contains difficult-to-control competitors such as black-grass, ryegrass and brome, it could be quite an easy decision to make. For example, if grass weeds have made it to the two-leaf stage or beyond, they will be very difficult to control as most contact herbicides have been rendered ineffective by mounting resistance.

 “In the most severe cases, it will make sense to admit defeat sooner rather than later and to write-off the current crop so that weeds can be burned off ahead of a replacement crop being established.”

 For many growers, Mr Thornton says it’s still not too late to get a replacement winter crop into the ground. For others, deferring to a spring-sown cropping strategy might be the better option.

 “In both cases, growers should be aware of the restrictions imposed by certain active ingredients on replacement crops. The best approach is to seek definitive advice from your agronomist and, where necessary, to implement a ‘plan B’ sooner rather than later.”

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Researchers analyze roadmaps toward larger, greener global rice bowl

Nebraska Today/University of Nebraska-Lincoln

Close-up of rice plants


Rice is the main food staple for more than half of the global population, and as the population grows, demand for rice is expected to grow, too.

But increasing global rice production is not a simple prospect.

“Global rice production is challenged now due to the negative environmental impact, water scarcity, labor shortage and slowing yield increases in many parts of the world,” said Shen Yuan, a postdoctoral research associate at Huazhong Agricultural University in China who spent two years as a visiting scholar at the University of Nebraska–Lincoln.

The challenge is producing more rice on existing cropland, and doing so while minimizing the environmental impact. New research led by Shaobing Peng, a professor of agronomy at Huazhong Agricultural University, and Patricio Grassini, associate professor of agronomy at Nebraska and co-leader of the Global Yield Gap Atlas, provides an analysis of roadmaps toward sustainable intensification for a larger global rice bowl. The research was published Dec. 9 in Nature Communications.

“Comparing rice cropping systems around the world in terms of productivity and efficiency in the use of applied inputs can help identify opportunities for improvement,” Grassini said.

The global assessment was led by Huazhong Agricultural University and the University of Nebraska–Lincoln, in collaboration with the University of California, Davis, and Texas A&M’s AgriLife Research Center in the United States; the International Rice Research Institute; Africa Rice Center; Indonesian Center for Rice Research and Assessment Institute of Agricultural Technology in Indonesia; Federal University of Santa Maria and EMBRAPA Arroz e Feijão in Brazil; National Institute of Agricultural Research in Uruguay; and Indian Institute of Farming Systems Research and Indian Institute of Water Management in India. The study assessed rice yields and efficiency in the use of water, fertilizer, pesticides and labor across 32 rice cropping systems that accounted for half of global rice harvested area.

“This study is the most comprehensive global evaluation of production systems for a major staple crop that I am aware of, and it will set the standard for future global comparison of such systems,” said Kenneth G. Cassman, professor emeritus at Nebraska and a co-author of the paper.

The good news, according to the study, is that there is still substantial room to increase rice production and reduce the negative environmental impact.

“Around two-thirds of the total rice area included in our study have yields that are below the yield that can be attained with good agronomic practices,” Yuan said. “Closing the existing yield gap requires better nutrient, pest, soil and water management, reduction of production risk and breeding programs that release rice cultivars with improved tolerance to evolving pests and diseases.”

Another important finding from the study is that food production and environmental goals do not conflict.

“We found that achieving high yields with small environmental impact per unit of production is possible,” Peng said. “Indeed, there is room for many rice systems to reduce the negative impact substantially while maintaining or even increasing rice yields.”

Producing more and minimizing the environmental footprint is an enormous challenge, Grassini said.

“Improved agronomic practices, complemented with proper institutions and policy, can help make rice cultivation more environmentally friendly,” Grassini said. “Our study marks a first step in identifying systems with the largest opportunities for increasing crop yields and resource-use efficiency, providing a blueprint to orient agricultural research and development programs at national to global scales.”SHARE1


Patricio Grassini, Associate Professor of Agronomy and Horticulture402-472-4398Website


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Massimo Pavan

Italy: “The summer season was a disaster due to the high temperatures and diseases”

Table tomatoes represent the most valuable vegetable and are among the most important consumer products. Massimo Pavan, an Italian expert and vice-president of Consorzio di Tutela del Pomodoro di Pachino Igp, explains how the summer was a disaster for growers. 

Now that the summer season has ended, the time has come for a winter season with table tomatoes grown in greenhouses in the Mediterranean areas, with Sicily standing out thanks to its prestigious productions.

“The summer season was a disaster due to the high temperatures and diseases. Although Tuta absoluta did not cause much trouble as it was exterminated by the high temperatures, there were other threats such as the Tomato Brown Rugose Fruit Virus. The drought that hit Sicily caused a 50% drop in production, leading to doubled production costs.”

“Although prices were rather high during the period in question, the favorable quotations were not enough to repay the losses in absolute terms. Cherry tomatoes, with peaks of over €2/kg, settled at an average of €1.50/kg. Thus, we were not pleased with the summer of 2021, especially considering the continuous price increases of the raw materials. Prices have increased so quickly that it is difficult to quantify the actual cost index. In addition, the cost of energy and fuel has also increased in October, which affected November production.”

“The prices are currently low, as is demand in foreign markets such as Germany and Austria. Production prices hover between €0.80 and €1.20/kg with considerable Moroccan competition in the European markets. We know November is traditionally a calmer month, but this month there is a lack of consumer trust, probably due to the uncertainty caused by Covid. In addition, they are starting to be affected by the higher cost of living. Because of that, producers are not seeing increases in sales. We are currently reaching the break-even point at €1.30/kg. We are talking about presumed indexes because the situation is still unclear. After all, assessments must be made at the end of the season. Anyway, we are working at a loss below this threshold, while last year production prices were €1.10/kg.”

“What seems to be happening is a reduction of the cultivation areas destined for tomatoes, which is what occurred in Spain. It will be a physiological consequence of a trend that is difficult to manage. Competition deals with quality, and ours is unbeatable. However, the Maghreb produce has lower prices. The reasons for this difference are well known, starting with the defense tools used in Morocco, which guarantee higher yields. Another determining factor is the cost of labor which, in the north-African country, is 8 times lower than in Italy.”

“Initiatives such as that promoted by Consorzio di Tutela del Pomodoro di Pachino Igp are welcome, as they focus on the sustainability of the product as a promotional strategy. Consumers have the certainty of purchasing a product that is monitored, healthy, and with an excellent flavor, and they can count on a carbon footprint that is exceptionally low, as greenhouses are not heated and do not release CO2 into the atmosphere, unlike what happens in northern Italy and Europe.”

Publication date: Wed 1 Dec 2021

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Is THIS the key to wiping out ? Removal of moisture has a 100% success rate at killing the invasive plant – and is much more effective than herbicide, study finds

  • Scientists said removing moisture from Japanese knotweed kills invasive plant
  • They had a ‘100 per cent success rate’ after drying out plants in lab conditions
  • Their discovery shows that the plant it ‘not as indestructible’, researchers said
  • Japanese knotweed is a plant found in many areas of Europe and North America


PUBLISHED: 07:06 EDT, 19 August 2021 | UPDATED: 07:39 EDT, 19 August 2021

Japanese knotweed is a devastatingly invasive plant that can leave homeowners and gardeners in a bind. 

But scientists might just have a new solution on how to kill it that they say is much more effective than herbicide.

It involves removing moisture from the plants by drying them out in a lab, although researchers said more tests in the field are needed to see how this would work in the real world before any advice or commercial product is made available to the public.https://imasdk.googleapis.com/js/core/bridge3.476.0_en.html#goog_1797203280PauseNext video0:24Full-screenRead More

The study by the National University of Ireland Galway and University of Leeds found that removing moisture had a ‘100 per cent success rate’ in killing Japanese knotweed, which can break through bricks, concrete and mortar.

Their discovery shows that the plant is ‘not as indestructible’ as thought, according to the study’s co-author Dr Mark Fennell.Scientists might just have a new solution on how to kill Japanese knotweed that they say is much more effective than herbicide. Pictured are some of the samples they experimented with+6

Scientists might just have a new solution on how to kill Japanese knotweed that they say is much more effective than herbicide. Pictured are some of the samples they experimented withJapanese knotweed (pictured) is a problematic plant found in many areas of Europe and North America. Notably, in the UK, the species can cause issues with mortgage acquisition+6

Japanese knotweed (pictured) is a problematic plant found in many areas of Europe and North America. Notably, in the UK, the species can cause issues with mortgage acquisition

Japanese knotweed 

Japanese Knotweed is a species of plant that has bamboo-like stems and small white flowers.

Native to Japan, the plant is considered an invasive species. 

The plant, scientific name Fallopia japonica, was brought to Britain by the Victorians as an ornamental garden plant and to line railway tracks to stabilise the soil.

It has no natural enemies in the UK, whereas in Asia it is controlled by fungus and insects.

In the US it is scheduled as an invasive weed in 12 states, and can be found in a further 29.

It is incredibly durable and fast-growing, and can seriously damage buildings and construction sites if left unchecked.

The notorious plant strangles other plants and can kill entire gardens. 

Capable of growing eight inches in one day it deprives other plants of their key nutrients and water.https://5772890968515b3f00a684ae0e95aa20.safeframe.googlesyndication.com/safeframe/1-0-38/html/container.html

The research found that incorrect herbicide treatment cannot control the growth and regeneration of Japanese knotweed, but that fully drying the plant material in a lab environment allowed it to be returned to the soil without risk of regrowth.

It also showed that if there are no nodes attached to the rhizomes (root-like underground shoots) there is no regeneration. Nodes are the points on a plant’s stem where buds and leaves originate.

Senior author of the study, Dr Karen Bacon, from NUI Galway, said: ‘Our finding that the removal of moisture has a 100 per cent success rate on killing Japanese knotweed plants and preventing regrowth after they were replanted also raises an important potential means of management for smaller infestations that are common in urban environments.’

She said it ‘requires additional field trials’ that her university hopes to carry out soon.

Japanese knotweed is a problematic plant found in many areas of Europe and North America. Notably, in the UK, the species can cause issues with mortgage acquisition. 

It can grow up to 10ft in height and can dominate an area to the exclusion of most other plants. 

Controlling Japanese knotweed is complicated by its ability to regenerate from small fragments of plant material; however, there remains uncertainty about how much rhizome is required and how likely successful regeneration is under different scenarios. 


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East Africa’s growers welcome new banana varieties more resistant to disease and drought

Breeders in Uganda and Tanzania have developed drought-tolerant and disease-resistant banana hybrids that are should support the commercialization of East Africa’s banana sector. The general response to the new hybrids has been positive from more than 1,350 Ugandan and Tanzania smallholder banana growers. These have very often struggled to sustain their plantations beyond four or five years in the face of intense pressure from plant diseases like Xanthomonas wilt (BXW), fusarium wilt and black Sigatoka.

Some regional agricultural analysts predict that East Africa’s banana farmers will soon enjoy the best of both worlds: bananas developed from conventional breeding and emerging biotechnologies like genome editing. The new advances also mean it’s highly likely that the region will be able to control the devastating Xanthomonas wilt (BXW) disease that has stymied production.

Dr. Ivan Kabiita Arinaitwe of Uganda’s National Banana Research Program told the Alliance for Science that the high- yielding new hybrids were developed through conventional breeding by crossing an East African highland banana cultivar (Triploid 3x) and a male diploid (2x) parent of the wild species Musa acuminata, which contributes the source of resistance to pests and diseases.

For East Africa, giving farmers access to improved banana hybrids mean increased and sustained commercial banana productivity, hunger mitigation, better food security and increased interventions aimed at strengthening and widening banana value addition for greater income generating opportunities.

Publication date: Mon 21 Jun 2021

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Road map for domesticating multi-genome rice using gene editing

Having more than two sets of chromosomes can help plants to adapt and evolve, but generating new crops with this type of genome is challenging. A road map for doing just that has now been developed using wild rice.

Diane R. Wang

We all sometimes wish we could do more than one thing at once — run errands, catch up on work deadlines and perhaps grab that long-overdue coffee with a friend. A genetic state known as polyploidy helps some plant genomes to do just this. Most plants, like humans, are diploid, with two sets of every chromosome. But polyploid plants have four, six or even eight sets of chromosomes. These additions allow different copies of a gene to take on different roles, and provide a buffer against potentially harmful mutations. Accordingly, polyploidy has served as a common mode of evolution in flowering plants1Writing in Cell, Yu et al.2 outline a viable approach to producing a domesticated form of polyploid rice using gene editing. Their advance could allow us to reap the benefits of polyploidy in one of the world’s most important crop species.Read the paper: A route to de novo domestication of wild allotetraploid rice

All crop species evolved from wild ancestors, as humans saved and propagated plants that had favourable attributes — loss of seed-dispersal mechanisms, for instance, and larger seeds and fruits3 — over hundreds or thousands of years. The world’s main rice crop, the Asian species Oryza sativa, was domesticated about 9,000 years ago from its wild progenitor, Oryza rufipogon, through processes thought to have occurred across multiple regions in Asia4,5. Both species are diploid, carrying two sets of 12 chromosomes.

For rice scientists, the idea of developing polyploid cultivated rice is tantalizing as a potential means for future crop improvement, especially in the face of climate variability6. The plant’s extra gene copies might enable rapid adaptation in response to major changes in the environment without the loss of favourable features7. But generating a polyploid rice from a cultivated diploid plant is hugely technically challenging. With that in mind, Yu et al. took an entirely different approach. The authors started with a distant, wild polyploid cousin of O. sativa and O. rufipogon, and domesticated it using biotechnological approaches (Fig. 1).

Figure 1
Figure 1 | A fast track to cultivated polyploid rice. Yu et al.2 have developed a strategy for rapid domestication of wild polyploid rice (which has more than two sets of chromosomes, unlike the rice commonly grown as a food crop). The first step is to select a wild strain that has favourable characteristics for gene editing and crop production. This is followed by genomic analysis and method optimization. Iterative cycles of genome editing, conventional crossing and testing are then needed before the new crop is rolled out to farmers and evaluated. Red highlights indicate sections of the road map completed by the authors for the wild rice Oryza alta.

The authors first spent time identifying an appropriate starting strain. The ideal candidate needed to be amenable to callus induction and regeneration — a process in which plant tissues are cultured to produce a mass of partially undifferentiated cells called a callus, from which new plants are generated. These properties are essential for gene-editing techniques. The selected individual also needed to have high biomass and tolerance to various abiotic and biotic stresses — heat and insect resistance, for example. After screening 28 polyploid wild rice lines, a strain of Oryza alta was selected, and named polyploid rice 1 (PPR1).

Oryza alta has four sets of chromosomes (it is tetraploid), and is found in Central and South America8. The species arose as a result of hybridization between two ancestors that had diploid genomes, designated C and D. The PPR1 strain selected by Yu et al. looks quite different from cultivated O. sativa. For instance, it is very tall — more than 2.7 metres, compared with 1 metre or less for typical O. sativa. It produces abundant biomass, and has broad leaves and sparse, small seeds adorned with awns (spiky protrusions thought to aid seed dissemination). As such, domesticating this wild relative was no small feat.

Yu and colleagues established methods for gene editing in PPR1, and assembled a high-quality genome for the strain. This acted as a map that helped identify genes to target for domestication. The authors compared PPR1 with an O. sativa genome dubbed Nipponbare. They discovered about 10,000 genes in each of the C and D genomes that did not have equivalents (homologues) in Nipponbare. By contrast, about 39,500 genes in Nipponbare (70.41% of the genome) did have homologues in PPR1.Multiple genomes give switchgrass an advantage

The latter was a promising result, because it meant that the genes responsible for domestication in O. sativa probably had related versions in PPR1. The researchers edited a suite of such genes in PPR1 that were known to have been involved in the domestication of O. sativa. This led to a range of improvements in PPR1: loss of shattering (a seed-dispersal mechanism), so that seeds did not fall off the plant before harvest; reduced awn length to ease post-harvest processing; increased grain length for larger kernels and greater yield; decreased height and thickened stem diameter to support the heavier grains; and modified (both longer and shorter) flowering times, needed for local adaptation to different latitudes.

Together, Yu and colleagues’ efforts led to the production of PPR1 lines with domesticated features in a just few generations, fast-tracking a process that typically occurs over hundreds to thousands of years. The work opens the door to developing plants that not only can better withstand environmental stresses (a crucial characteristic for global food security in the face of changing climates), but also could carry other characteristics — enhanced nutrition and taste, for example — that might help rice to meet evolving consumer preferences in the future. In addition, the strategy the authors have devised could theoretically provide a road map for applying biotechnology to drive the domestication of wild relatives of other present-day crops.Keen insights from quinoa

The techniques established by Yu et al. await testing in other wild, tetraploid rice strains. Successful extension to a broader gene pool will be necessary if researchers and breeders are to generate a diverse repository of domesticated polyploids, which could then be used to generate further improved strains through conventional crosses or genome editing — strains adapted to particular production systems, for instance, or those with high market acceptability. And although wild polyploids hold great promise as yet-untapped sources of genes that confer tolerance to abiotic stresses such as drought, these traits are likely to be complex, as noted by the authors, being influenced by many genes, each of which has only a small effect. A deeper understanding of the genetics of these plants is needed for the full potential of wild rices to be appreciated.

There is a long journey ahead for the breeding of cultivated polyploid rice. But the first seeds have now been sown. As demand for nimble and resilient food systems rises, rapid domestication and improvement of wild plant species, including polyploids, may well become a valuable instrument in agriculture’s toolbox.doi: https://doi.org/10.1038/d41586-021-00589-9

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Relationship between Nitrogen and crop disease

  1. The Crescent News
  2. By Hoorman Soil Health Services
  3. Feb 25, 2021 Updated Feb 25, 2021

Nitrogen (N) is the fourth most abundant plant nutrient with about 80-85% N sequestered in protein, 10% in genetic components (DNA & RNA), and 5% in amino acids (protein building blocks). Nitrogen makes proteins like enzymes (speed up chemical reactions), hormones (regulate plant functions), and N increases cell growth. Nitrogen strengthens plant cell walls (cellulose), is used in plant energy transfer (ATP), and in photosynthesis (chlorophyll); effecting many plant processes. If a plant has balanced N, it has less disease; but when N is either deficient or in excess, expect more disease and insect problems in the field, garden, with ornamentals, or house plants.https://e58b06d6ddf80758d88dccc3cc17f20d.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.html

The rate of N application and the form depends on the plant’s life cycle. Nitrogen deficiency or excess N may change the cell wall to become leaky, promoting more diseases. Early on, plants need more nitrates for growth with ammonium sources increasing as the plant matures to increase yield. N stressed deficient plants can’t make full proteins while excess N lowers plant defenses to both disease and insects. Plants typically absorb N in the oxidized form as nitrate (NO3-) or the reduced form as ammonium ( NH4+). Ammonium is 25% more plant efficient than nitrates because it can be easily converted to amino acids but to avoid toxicity, plants need it in small doses and it is easily converted to soil nitrate. Soil health keeps these N forms plant available to optimize plant growth and yield.

Nitrogen interacts with many other plant nutrients. Potassium (K) promotes the increase of nitrates and plant growth, but too much K decreases yield. Adequate phosphorous plus chlorine decreases nitrates and enhances plant ammonium N forms to increase yield. In soybeans, calcium and cobalt are needed for Rhizobium microbes to fix atmospheric N into protein. Supplementing cobalt (a micronutrient) and calcium in soybeans at the right time may increase soybean yields by 3x. Molybdenum, manganese, iron, and magnesium are involved in nitrogen transformations and protein synthesis. As my high school math teacher (Dave Laudick) use to say: It’s as clear as mud. Soil organic matter is a storehouse of many essential micronutrients and allows soil microbes and plants to thrive in a buffered and safe environment. Yes, it’s complicated but worth knowing if yields improve.

Common N related corn diseases are gray leaf spot, stalk rot due to late season N stress (N deficient), and increased aflatoxin due to high nitrates. In soybeans, to much N increases mosaic virus and Rhizoctonia. In wheat, take-all is increased by nitrates, decreased by ammonium; too much N increased powdery mildew; but higher N levels decreases Stagonospora nodurum. Balanced N fertilization is a key to decreasing most diseases.

Time of N fertilization is important. Corn side dressing reduces N leaching and denitrification losses but also decreases Pythium and Rhizoctonia BUT may increase Fusarium and Gibberella stalk rot. Adding a N inhibitor to fertilizer or liquid manure may decrease corn stalk rot by keeping N in the ammonium form late season. In soybeans, avoid over using glyphosate because it chelates or ties up manganese, iron, calcium, and zinc which can affect plant N fixation. In wheat, delaying N fertilizer until spring promotes take-all but avoids excess winter N when its cold and wet, so less Rhizoctonia. Best solution, put on a small amount of N in fall to promote tillering and delay spring N applications until late spring using granular or urea forms of N to reduce foliar leaf stress from liquid N sources.

There are four strategies to reducing diseases associated with nitrogen. The 4 R’s are the right form, right time, right rate, and right place. Use a balanced N fertilizer program with sufficient N in the right form for optimum growth. For corn starter, 25% nitrates and 75% ammonium, is a good mix but placement (2”X2”, 2”X4”) is critical to avoid root stress. Weather, pH, soil conditions (compaction), soil texture, moisture, biological activity, etc. all affect N transformations and plant uptake. Building SOM buffers soils and helps control or moderate these factors. Make timely N applications to avoid N deficiency, excesses, or losses. Modify the soil environment by changing pH (lime), add cover crops to build soil organic matter, reduce soil compaction, add a N inhibitor, avoid over using glyphosate, or supplement with micronutrients to assist in optimal N utilization and less crop disease. Source: Mineral Nutrition and Plant Disease, 2018.

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science daily

Nanosensor can alert a smartphone when plants are stressed

Carbon nanotubes embedded in leaves detect chemical signals that are produced when a plant is damaged

April 15, 2020
Massachusetts Institute of Technology
Engineers can closely track how plants respond to stresses such as injury, infection, and light damage using sensors made of carbon nanotubes. These sensors can be embedded in plant leaves, where they report on hydrogen peroxide levels.

MIT engineers have developed a way to closely track how plants respond to stresses such as injury, infection, and light damage, using sensors made of carbon nanotubes. These sensors can be embedded in plant leaves, where they report on hydrogen peroxide signaling waves.

Plants use hydrogen peroxide to communicate within their leaves, sending out a distress signal that stimulates leaf cells to produce compounds that will help them repair damage or fend off predators such as insects. The new sensors can use these hydrogen peroxide signals to distinguish between different types of stress, as well as between different species of plants.

“Plants have a very sophisticated form of internal communication, which we can now observe for the first time. That means that in real-time, we can see a living plant’s response, communicating the specific type of stress that it’s experiencing,” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT.

This kind of sensor could be used to study how plants respond to different types of stress, potentially helping agricultural scientists develop new strategies to improve crop yields. The researchers demonstrated their approach in eight different plant species, including spinach, strawberry plants, and arugula, and they believe it could work in many more.

Strano is the senior author of the study, which appears today in Nature Plants. MIT graduate student Tedrick Thomas Salim Lew is the lead author of the paper.

Embedded sensors

Over the past several years, Strano’s lab has been exploring the potential for engineering “nanobionic plants” — plants that incorporate nanomaterials that give the plants new functions, such as emitting light or detecting water shortages. In the new study, he set out to incorporate sensors that would report back on the plants’ health status.

Strano had previously developed carbon nanotube sensors that can detect various molecules, including hydrogen peroxide. About three years ago, Lew began working on trying to incorporate these sensors into plant leaves. Studies in Arabidopsis thaliana, often used for molecular studies of plants, had suggested that plants might use hydrogen peroxide as a signaling molecule, but its exact role was unclear.

Lew used a method called lipid exchange envelope penetration (LEEP) to incorporate the sensors into plant leaves. LEEP, which Strano’s lab developed several years ago, allows for the design of nanoparticles that can penetrate plant cell membranes. As Lew was working on embedding the carbon nanotube sensors, he made a serendipitous discovery.

“I was training myself to get familiarized with the technique, and in the process of the training I accidentally inflicted a wound on the plant. Then I saw this evolution of the hydrogen peroxide signal,” he says.

He saw that after a leaf was injured, hydrogen peroxide was released from the wound site and generated a wave that spread along the leaf, similar to the way that neurons transmit electrical impulses in our brains. As a plant cell releases hydrogen peroxide, it triggers calcium release within adjacent cells, which stimulates those cells to release more hydrogen peroxide.

“Like dominos successively falling, this makes a wave that can propagate much further than a hydrogen peroxide puff alone would,” Strano says. “The wave itself is powered by the cells that receive and propagate it.”

This flood of hydrogen peroxide stimulates plant cells to produce molecules called secondary metabolites, such as flavonoids or carotenoids, which help them to repair the damage. Some plants also produce other secondary metabolites that can be secreted to fend off predators. These metabolites are often the source of the food flavors that we desire in our edible plants, and they are only produced under stress.

A key advantage of the new sensing technique is that it can be used in many different plant species. Traditionally, plant biologists have done much of their molecular biology research in certain plants that are amenable to genetic manipulation, including Arabidopsis thaliana and tobacco plants. However, the new MIT approach is applicable to potentially any plant.

“In this study, we were able to quickly compare eight plant species, and you would not be able to do that with the old tools,” Strano says.

The researchers tested strawberry plants, spinach, arugula, lettuce, watercress, and sorrel, and found that different species appear to produce different waveforms — the distinctive shape produced by mapping the concentration of hydrogen peroxide over time. They hypothesize that each plant’s response is related to its ability to counteract the damage. Each species also appears to respond differently to different types of stress, including mechanical injury, infection, and heat or light damage.

“This waveform holds a lot of information for each species, and even more exciting is that the type of stress on a given plant is encoded in this waveform,” Strano says. “You can look at the real time response that a plant experiences in almost any new environment.”

Stress response

The near-infrared fluorescence produced by the sensors can be imaged using a small infrared camera connected to a Raspberry Pi, a $35 credit-card-sized computer similar to the computer inside a smartphone. “Very inexpensive instrumentation can be used to capture the signal,” Strano says.

Applications for this technology include screening different species of plants for their ability to resist mechanical damage, light, heat, and other forms of stress, Strano says. It could also be used to study how different species respond to pathogens, such as the bacteria that cause citrus greening and the fungus that causes coffee rust.

“One of the things I’m interested in doing is understanding why some types of plants exhibit certain immunity to these pathogens and others don’t,” he says.

Strano and his colleagues in the Disruptive and Sustainable Technology for Agricultural Precision interdisciplinary research group at the MIT-Singapore Alliance for Research and Technology (SMART), MIT’s research enterprise in Singapore, are also interested in studying is how plants respond to different growing conditions in urban farms.

One problem they hope to address is shade avoidance, which is seen in many species of plants when they are grown at high density. Such plants turn on a stress response that diverts their resources into growing taller, instead of putting energy into producing crops. This lowers the overall crop yield, so agricultural researchers are interested in engineering plants so that don’t turn on that response.

“Our sensor allows us to intercept that stress signal and to understand exactly the conditions and the mechanism that are happening upstream and downstream in the plant that gives rise to the shade avoidance,” Strano says.

The research was funded by the National Research Foundation of Singapore, the Singapore Agency for Science, Technology, and Research (A*STAR), and the U.S. Department of Energy Computational Science Graduate Fellowship Program.

Story Source:

Materials provided by Massachusetts Institute of Technology. Original written by Anne Trafton. Note: Content may be edited for style and length.

Journal Reference:

  1. Tedrick Thomas Salim Lew, Volodymyr B. Koman, Kevin S. Silmore, Jun Sung Seo, Pavlo Gordiichuk, Seon-Yeong Kwak, Minkyung Park, Mervin Chun-Yi Ang, Duc Thinh Khong, Michael A. Lee, Mary B. Chan-Park, Nam-Hai Chua, Michael S. Strano. Real-time detection of wound-induced H2O2 signalling waves in plants with optical nanosensors. Nature Plants, 2020; 6 (4): 404 DOI: 10.1038/s41477-020-0632-4

Cite This Page:

Massachusetts Institute of Technology. “Nanosensor can alert a smartphone when plants are stressed: Carbon nanotubes embedded in leaves detect chemical signals that are produced when a plant is damaged.” ScienceDaily. ScienceDaily, 15 April 2020. <www.sciencedaily.com/releases/2020/04/200415133512.htm>.

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