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Rewiring Plant Defence Genes to Reduce Crop Waste

Article ID: 696239

Released: 18-Jun-2018 12:05 PM EDT

Source Newsroom: University of Warwick

  • Plants could be genetically rewired to better resist disease, helping safeguard crop yields worldwide – new research by the Universities of Warwick and York
  • Defensive feedback control system developed – enables plants to strengthen their defences to withstand attack by re-wiring existing gene connections
  • System uses same approach as aircraft autopilots use to counteract turbulence

Plants can be genetically rewired to resist the devastating effects of disease – significantly reducing crop waste worldwide – according to new research into synthetic biology by the University of Warwick.

Newswise — Led by Professor Declan Bates from the Warwick Integrative Synthetic Biology Centre (WISB) and Professor Katherine Denby from the University of York, who is also an Associate member of WISB, researchers have developed a genetic control system that would enable plants to strengthen their defence response against deadly pathogens – so they could remain healthy and productive.

When pathogens attack crop plants, they obtain energy and nutrients from the plant but also target the plant’s immune response, weakening defence, and making the plants more vulnerable.

Building on experimental data generated by Prof. Denby, Professor Bates’ group simulated a pathogen attack in Arabidopsis plants, and modelled a way to rewire the plants’ gene network, creating a defensive feedback control system to combat disease – which works in much the same way as an aircraft autopilot.

Just as an aircraft’s autopilot control system detects disturbances like wind gusts or turbulence and acts to reject them, this new plant control system detects a pathogen attack, and prevents the pathogen weakening the plants’ defence response.

This method could render crops more resilient against disease, helping mitigate crop wastage throughout the world. Since the system can be implemented by re-wiring plants’ natural defence mechanisms, no external genetic circuitry needs to be added.

Declan Bates, Professor of Bioengineering at the University of Warwick’s School of Engineering, commented:

“Disease, drought and extreme temperatures cause significant yield losses in crop plants all over the globe, threatening world food security. It is therefore crucial to explore new ways to develop crops that are resilient to pathogen attacks and can maintain yields in challenging environments. This study shows the enormous potential of using feedback control to strengthen plants’ natural defence mechanisms.”

Katherine Denby, Professor of Sustainable Crop Production and Director of the N8 AgriFood Resilience Programme at the University of York commented:

“Minimising crop waste is obviously an essential part of creating a more sustainable food system. What is exciting here is applying engineering principles to plant biology to predict how to re-design plant gene regulation to enhance disease resistance. We use re-wiring of existing genes in the plant to prevent pathogen manipulation”

The next steps of the research will be to take the theory into the lab, and experimentally implement the defensive feedback control system in plants.

18 June 2016

Notes to editors:

The research, ‘A Framework for Engineering Stress Resilient Plants Using Genetic Feedback Control and Regulatory Network Rewiring’, is published in ACS Synthetic Biology, a journal of the American Chemical Society.

It is authored by Declan G. Bates, Mathias Foo, Iulia Gherman, Peijun Zhang, and Katherine J. Denby.

 

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Researchers discover wild tomato resistant to a wide range of pests and insects

Scientists at the University of Wageningen (The Netherlands) have discovered a species of wild tomato from the Galapagos Islands that is resistant to a wide range of insect pests. The wild tomato is genetically closely related to the cultivated tomato, which makes it easy to cross-breed it at the agricultural level and make it resistant to different insects.
Cultivated tomatoes are more vulnerable to pests and diseases, since they have lost their natural resistance in the reproduction process. Researchers are working to reverse this by reintroducing the resistance of the wild varieties through breeding, but they still haven’t been able to successfully cross breed the wild tomatoes with the cultivated tomatoes to obtain the necessary traits. The wild tomato of the Galapagos Islands, however, is genetically very similar to the cultivated tomato, and its resistance is encoded within a single chromosome, which should make crossing between the existing plants much easier.
Ben Vosman, a scientist at Wageningen University, said “we work with samples of the wild tomato species Solanum galapagense from a gene bank. The first discovery was that this tomato species is resistant to whiteflies. Then, we discovered it was actually resistant to many other insects as well, including the green peach aphid and the caterpillars of the soldier beetworm. It was a very pleasant surprise.” They have been working on this research since 2010,
“If we can make the cultivated tomatoes resistant to whiteflies, this will directly benefit the environment,” Vosman said. While this problem is still relatively manageable in greenhouses, through integrated control, for example, there are also pests there. In the field crops, the problems with insects are much greater. “We hope that most of the advantages are in the field crops and in the tropics,” he added.
Source: Wageningen University & Research

 

Publication date: 5/3/2018

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Rice heads

LSU AgCenter releases new rice hybrid

A new hybrid rice with high quality and competitive yield potential is being released by the LSU AgCenter.

Bruce Schultz 1 | Apr 05, 2018

A new hybrid rice with high quality and competitive yield potential is being released by the LSU AgCenter.

The long-grain hybrid, LAH169, was developed at the H. Rouse Caffey Rice Research Station during the past seven years.

The rights to commercial development will be available for bidding. The date for submitting bids will be announced after details are finalized, according to Alana Fernandez of the LSU AgCenter Office of Intellectual Property.

LSU AgCenter hybrid rice breeder Jim Oard said LAH169 has good grain quality with low chalk. “It has 50 percent less chalk than the commercial hybrids currently available,” he said.

He said LAH169 can have a respectable yield.

“The main crop yield performance of LAH169 in 25 trials in five locations across three years in Louisiana was 94 percent of RiceTec CLXL745, the most popular hybrid in Louisiana,” Oard said. “In limited trials across two years, the combined main and ratoon yields of LAH169 were nearly identical to CLXL745.”

The new hybrid is moderately resistant to blast, sheath blight and panicle blight, he said.

Seed crop

A seed crop of LAH169 has been grown at the LSU AgCenter winter nursery in Puerto Rico, Oard said. That rice will be harvested in April and will be stored at the Rice Research Station until a partner to increase seed has been identified.

Oard said hybrid development will continue. “We have a Clearfield hybrid in the pipeline,” he said.

Also available for the first time is a new Clearfield Jasmine-type rice named CLJ01.

It is superior to its aromatic predecessors, Jazzman-1 and Jazzman-2, in terms of yield and quality, said AgCenter rice breeder Adam Famoso.

The biggest difference is yield. “Over three years of tests off-station, on average it’s been 30 percent or better than Jazzman-2,” Famoso said.

Its aroma is on par with Thai Jasmine, he said.

Its quality is exceptional, with the lowest chalk of any rice grown at the Rice Research Station, Famoso said.

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ICAR- Indian Institute of Horticultural Research

Arka Rakshak: High yielding triple disease resistant tomato F1 hybrid with export potential

Arka Rakshak: High yielding triple disease resistant tomato F1 hybrid with export potential Tomato (Solanum lycopersicum L.) is the second most important vegetable crop in India next only to potato. In India, it is cultivated over an area of 8.79 lakh hectares with a production of 182.26 lakh tonnes. The average productivity is about 20.7 tonnes per hectare. Andra Pradesh, Odissa, Madhya Pradesh, Karnataka, West Bengal, Maharashtra, Chhatishgarh and Gujarat are the major tomato-growing states in India. In recent years the occurrence of major diseases such as Tomato leaf curl virus (ToLCV), bacterial wilt (BW) and early blight (EB) have become very serious causing considerable yield loss in major tomato growing areas of the country. Due to ToLCV, yield loss has been reported up to 70-100% depending on the stage of attack, bacterial wilt has been reported to cause yield loss up to 70%, where as, early blight has become very serious on foliage and fruits causing yield loss up to 50-60%. DSCF1192 2 Leaf curling due toToLCV Sudden wilting due to BW Scan790 DSC01838 Concentric rings- symptoms on leaf & fruits due to EB Adoption of multiple disease resistant tomato variety / F1 hybrid is the most practical way to combat these serious diseases as no chemical application can effectively control them. Research efforts were carried out for several years at Indian Institute of Horticultural Research (IIHR), Bangalore and a high yielding tomato F1 hybrid “Arka Rakshak” was bred with triple disease resistance to ToLCV + BW + EB by crossing an advanced breeding line bred at IIHR with another breeding line bred at Asian Vegetable Research and Development Center (AVRDC), Taiwan. This is the first multiple disease resistant public bred tomato F1 hybrid released for commercial cultivation in the country. Interdisciplinary approach involving a breeder, virologist, bacteriologist, pathologist and molecular biologist was successfully adopted to breed Arka Rakshak . Further efforts are on the way to introgress late blight resistance genes in to Arka Rakshak back ground through Marker Assisted Breeding. Salient Features of Arka Rakshak Arka Rakshak: A High yielding F1 hybrid with triple disease resistance to tomato leaf curl virus, bacterial wilt and early blight. Plants are semi-determinate with dark green foliar cover. Fruits are oblong with light green shoulder. Fruits are medium to large size (80-100g), deep red, very firm with good keeping quality (15-20 days) and long transportability. Bred for both fresh market and processing. Suitable for summer, kharif and rabi seasons. Yields 90-100 tons per hectare in 140-150 days. Arka Rakshak- High yielding triple disease resistant F1 hybrid with excellent fruit quality attributes Updated on 01.08.2014

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basmati-farmer

A farmer in Jind, Haryana in his  basmati paddy field. (Express photo: Renuka Puri)

Pesticide residues are an issue, more so when it concerns products such as basmati rice, fetching the country annual export revenues ranging from $ 3.23 billion in 2016-17 to $ 4.52 billion in 2014-15. The burden of consignments being rejected ultimately falls on the farmer, who has to, then, use new-generation pesticides that are safer, but costlier and very often proprietary/patented molecules.

The most recent example is of Tricyclazole. A single 120-gram spray of this common fungicide, against leaf and neck blast disease in paddy, hardly costs Rs 150-170 per acre. But with the European Union (EU) deciding not to allow import of any rice having Tricyclazole levels above 0.01 parts per million (ppm) from January 1, farmers would find it difficult to spray the generic chemical sold under assorted brands like ‘Sivic’, ‘Baan’ and ‘Beam’. The existing tolerance limit stipulated by the EU (which accounts for about 3.5 lakh tonnes of India’s total annual basmati shipments of 40 lakh tonnes) for Tricyclazole is one ppm or 1 mg/kg; 0.01 ppm will make it 1mg/100 kg!

With Tricyclazole ruled out, farmers may, henceforth, have to go for fungicides that are considered environmentally friendlier, though costing ten times more. These include Azoxystrobin (a single 200-ml spray, sold under the Swiss company Syngenta’s ‘Amistar’ brand, costs around Rs 900 per acre) and Picoxystrobin (the cost of a single 400-ml spray of this formulation, sold under DuPont’s ‘Galileo’ brand, comes to Rs 1,300 per acre). No less expensive is ‘Nativo’. This combination fungicide of Bayer CropScience, containing Tebuconazole and Trifloxystrobin, costs Rs 1,000 for a single 160-gram spray per acre.

However, an alternative approach to pesticide application — necessary, especially keeping in view basmati’s premium quality attributes and huge export market — is to “breed for disease resistance”. This involves transfer of specific disease-resistance genes, from both traditional landrace cultivars and wild relatives of paddy, into existing high-yielding basmati varieties. That is what scientists at the Indian Agricultural Research Institute (IARI) have sought to do.

The New Delhi-based institute — under a collaborative project with the Indian Council of Agricultural Research’s National Research Centre on Plant Biotechnology — has transferred the ‘Pi9’ gene into its popular Pusa Basmati-1 variety. This gene, sourced from Oryza minuta (a wild relative of Oryza sativa, which is the normal cultivated paddy), provides “very high resistance” against leaf blast and “moderate resistance” against neck blast fungus.

The resultant variety, which is called Pusa Basmati-1637, combines Pusa Basmati-1’s high-yielding trait with resistance against a fungus that infests the leaf and neck nodes of the rice plant’s main stem, from where the grain-bearing earheads (panicles) emerge. Blast disease affecting the leaf basically damages the chlorophyll, thereby impeding photosynthesis that involves absorption of sunlight and using its energy to synthesise carbohydrates. Neck blast, if severe, can cause the stem to even break. If the panicles at that point have only partially formed grains, in their early milky stage, the yield losses can be huge.

Rajeev Kharb, a farmer from Tito Kheri village in Safidon tehsil of Haryana’s Jind district, has grown Pusa Basmati-1637 in five out of his total 80-acre holding. The latter includes 28 acres of own and 52 acres of leased land. High temperatures and humidity levels this time round has resulted in the bulk of his planted area – mainly under Pusa Basmati-1401, Pusa Basmati-1 and Pusa Basmati-1509 – suffering gardan-marod (the local term for blast, whose literal translation is “curling of the neck”) to the extent of 10-20 per cent.

“But nothing has happened to my Pusa Basmati-1637 field. This, even without spraying any Tricyclazole,” says Kharb. A loss of 10-20 per cent isn’t small. Taking per-acre yields of 22-25 quintals for Pusa Basmati-1, 25-28 quintals for Pusa Basmati-1509 and 28-30 quintals for Pusa Basmati-1401, and current average price realisations of Rs 2,800/quintal, it works out to anywhere from Rs 7,000 to Rs 14,000 per acre.

“We will continue to have to spray for other diseases (bacterial blight and sheath blight fungus) and pests (brown plant hopper and stem borer). But with this new variety, there is still significant savings from not using Tricyclazole or other expensive fungicides against blast,” points out Pritam Singh Hanjra, a progressive farmer from Urlana Khurd village in Madlauda tehsil of Panipat district.

Hanjra, who has sown Pusa Basmati-1637 in five out of his 105-acre holding (30 acres own and the rest leased), estimates expenses on crop protection chemicals at Rs 3,000-4,000 out of the total cultivation costs of Rs 20,000-22,000 per acre for paddy. “It can go up, depending on the extent of pest and disease incidence. Either way, this is the second biggest expenditure head after manual harvesting-and-threshing (Rs 4,500-5,000), and more than fertilizers (Rs 2,100-2,200),” he claims.

A K Singh, head of IARI’s Division of Genetics, notes that Indian breeders have, over a period, managed to raise crop yields. The traditional tall basmati cultivars, for instance, gave barely 8-10 quintals of paddy per acre. With improved dwarf high-yielding basmati varieties, these have gone up to 25 quintals or so. “Our challenge now is to protect these yields and preferably through breeding for resistance, as opposed to pesticide application,” he adds.

IARI is, in fact, working on transferring other blast resistance genes as well — such as ‘Pi54’, ‘Pi25’, ‘Pi2’ and ‘Pib’, all from wild relatives and land races of rice — to high-yielding basmati varieties.

“We want to do pyramiding of these genes (combining two or more of them), in order to impart more durable resistance against blast. Besides, we have already developed and released two new varieties, Pusa Basmati-1718 and Pusa Basmati-1728, both of them incorporating the Xa21 and xa13 genes that confer resistance to the bacterial blight pathogen. The first variety is basically Pusa Basmati-1121 and the second one Pusa Basmati-1401, containing both these genes obtained from Oryza longistaminata (another wild relative of paddy) and BJ1 (a traditional land race), respectively,” informs Singh.

 

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Growing Produce

Silicon: a Biocontrol Agent that Boosts Plant Immunity

Quality and profitability are two important factors that drive our agricultural markets. We have fine-tuned our cultivation processes over centuries to obtain higher yields with lower inputs to protect both our environment and our bodies.

The biocontrol market contains a diverse set of less-toxic alternatives to aid in the overall goal of environmental stewardship. One set of materials contain a bioavailable form of silicon, important for enhancing the plant’s natural immune system.

Silicon is an essential trace element important for animal and human health. It also has an important role in plant health.

Silicon Protects Against Some Disease And Insect Pests
Studies show that adding silicon to the growing media significantly reduces the presence of powdery mildew in a variety of plants, including cucumber, tomatoes, strawberries, grapes, melons, and lettuce. This nutrient also protects against bacterial and viral infections in certain plants.

Not only does silicon protect against disease, it also reduces the population of insects and mites feeding on silicon-treated plants.

For many years, it was thought that silicon provided a physical barrier associated with the plant cuticle, making it harder for insects to penetrate.

While this process is involved, recent studies show that arthropods feeding on silicon-treated plants produce fewer offspring, suggesting that silicon is altering some aspect of the plant material ingested by these menaces. Combining silicon with other biocontrol agents may lead to better protection and control over infestations.

Tips on Gaining Nutrition from Silicon
There are many forms of silicon that can be taken up by plants.

Commercially available products include:
■ Solid materials for media incorporation that come from mined rocks (wollastonite and ignimbrite)
■ Recycled slag from the steel industry (also containing additional micronutrients and used as alternative liming agents)
■ Recycled glass (used as solid substrate in hydroponics or aquaponics)
■ Plant material (including rice hulls, coir, and biochar produced from plant material).
■ Liquid materials that can be applied as a media drench or foliar spray (including potassium-, sodium-, and calcium-silicates).

These materials have unique characteristics and release varying amounts of plant-available silicon. It is important to match the material with your growing system.

The amount of silicon required to enhance growth and stress resistance varies greatly by plant type and even variety. There are no current recommendations for silicon concentrations in plant tissue.

As a general rule of thumb, many of the grasses and grains need large amounts (and can take up to 100,000 ppm or higher silicon), while dicots range in their foliar concentrations from 10,000 ppm (in cucumber) to 100 ppm (in onion). It is important to note that silicon protects both cucumber and onion in various stress responses, showing that foliar concentration does not predict protection.

Silicon fits in as a biocontrol because it enhances the plant’s own immune response, allowing for a faster and more robust response to invading pathogens or herbivores. By providing plants with this nutrient prior to the onset of disease or early in the detection of nuisance arthropods, we can help our photosynthetic friends maintain their quality and yield, even in the presence of stress.

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Diamondback-moth

CAAS Scientists Develop GE Cabbage Resistant to Diamondback Moth

Chinese Academy of Agricultural Sciences researchers successfully incorporated a Bt gene into cabbage plants to improve resistance to destructive pest, diamondback moth (Plutella xylostella). The results of their study are published in Scientia Horticulturae.

The researchers used Agrobacterium tumefaciens-mediated transformation to develop transgenic cabbage plants with Bacillus thuringiensis cry1Ia8 gene. The resulting transgenic plants were able to control both susceptible and Cry1Ac-resistant diamondback moth larvae.Then they analyzed the expression and inheritance of the Bt gene in four single-copy lineages and their sexually derived progenies.

Results of the analyses showed that the transgene was successfully inserted in the genome of cabbage and the inheritance of the gene in the progenies followed the Mendelian segregation pattern. These results imply that the transgenic lines exhibiting stable inheritance can be used as donor in breeding programs for cabbage.

Read the research article for more information.

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