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Matt Hayes:

‘Researchers help inform cassava breeding worldwide’

“Scientists in Cornell’s NextGen Cassava project have uncovered new details regarding cassava’s genetic architecture that may help breeders more easily pinpoint traits for one of Africa’s most vital crops.

Their findings are reported in a study published July 31 in Plant Molecular Biology.

The scientists analyzed large breeding populations measured extensively over successive years and stages of selection in multi-environment field trials in Nigeria. The genome-wide association analysis explored genomic regions most responsible for desirable traits in cassava, a food crop that provides the main source of calories for 500 million people across the globe.

The scientists found more than 40 quantitative trait loci associated with a total of 14 traits, responsible for characteristics such as disease responses, nutritional quality and yield. The traits were classified broadly into four categories – biotic stress, quality, plant agronomy and agro-morphology.

“Our findings provide critical new entries into the catalogue of major loci available to cassava breeders,” said Ismail Rabbi, a molecular geneticist and plant breeder at the International Institute of Tropical Agriculture (IITA) and a member of the NextGen project. “These markers should greatly improve cassava research and provide another powerful tool for the breeders’ toolbox.”

“Cassava is an incredibly useful food and industrial crop today and will be more so in the future as climate change reshapes agriculture everywhere, but first we must better understand its complex genome,” said Chiedozie Egesi, NextGen program director and co-author on the study.

Based in the Department of Global Development, the NextGen Cassava Breeding project supports scientists from many disciplines with advanced technologies and methods. The project works to empower smallholder cassava farmers in sub-Saharan Africa by developing, releasing and distributing improved cassava varieties.

Plant diseases and pests like cassava mosaic disease (CMD) and cassava green mite are major constraints to cassava production in Africa, India and across Asia, including Vietnam and Thailand. Infections of CMD can lead to yield losses of 82%, or more than 30 million tons each year.

“A complete understanding of cassava’s genetic architecture is the critical step needed to accelerating genetic improvement and bring lasting benefits to farmers and consumers who depend on this crop for food and income throughout the world,” said Egesi, who’s also a visiting scientist in the Department of Global Development and an adjunct professor of plant breeding and genetics in the School of Integrative Plant Science, in the College of Agriculture and Life Sciences.

While the findings revealed novel genomic regions, it also revealed additional markers associated with previously measured traits.

Data from the study was made freely available through several commercial genotyping service vendors. The scientists plan further studies using germplasm from other regions, including East Africa and Latin America, which they say should bolster the catalogue of major effect loci available for molecular breeding.

Study co-authors include Cornell adjunct professor Jean-Luc Jannink and researchers from IITA and the National Root Crops Research Institute in Nigeria. Researchers from the Boyce Thompson Institute and the U.S. Department of Agriculture-Agriculture Research Service also contributed.

NextGen Cassava is funded by the Bill & Melinda Gates Foundation and by UK Aid, a British government initiative.

Matt Hayes is associate director for communications for Global Development in the College of Agriculture and Life Sciences.”

By Matt Hayes for Cornell University

Publication date: Thu 27 Aug 2020

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cover cropsJosh HiemstraPLANTING GREEN: Seventy-one percent of farmers responding to a national cover crop survey reported they had better weed control by planting green, and 68% reported better soil moisture management even during a wet spring.

National survey reveals farmers like cover crops

Survey documents a wide range of benefits as acreage expands.

Fran O’Leary | Aug 20, 2020

“Many U.S. farmers have turned to cover crops as part of their strategy to improve soil health while reducing input costs and maintaining yields,” reports Mike Smith, who managed the national survey for the nonprofit organization Conservation Technology Information Center.

Survey participants averaged 465 acres in cover crops in 2019, an increase of 38% in four years. The USDA Census of Agriculture found a 50% increase in cover crop acreage during the five-year period between 2012 and 2017.https://tpc.googlesyndication.com/safeframe/1-0-37/html/container.html

Multiple benefits

“Farmers are using cover crops for a variety of reasons, and many have tried new approaches to cover cropping,” Smith says. “This year’s survey also indicated that some of the concerns that many growers have had about the effects of cover crops on planting dates in a wet year turned out not to be true. In fact, in many cases, cover crops helped farmers plant earlier in the very wet spring of 2019.”

Despite the crippling rainfall that significantly delayed planting across much of the country in 2019, more than 90% of farmers participating in the survey reported that cover crops allowed them to plant earlier or at the same time as fields without cover crops. Among those who had “planted green,” seeding cash crops into growing cover crops, 54% said the practice helped them plant earlier than on other fields.

These findings are among several new insights from the 2019-20 National Cover Crop Survey, conducted by CTIC with financial support from the Sustainable Agriculture Research and Education program and the American Seed Trade Association. These organizations have worked together on several past national cover crop surveys, with the first survey dating back to 2012.

The 2019-20 survey, which includes perspectives from 1,172 farmers representing every state, is the first by SARE, CTIC and ASTA to include detailed exploration of planting green — a tactic employed by 52% of the respondents — as well as crop insurance use among cover croppers and the impact of cover crops on the profitability of horticultural operations.

According to Rob Myers, regional director of Extension programs for North Central SARE, “Many farmers are finding that cover crops improve the resiliency of their soil, and the longer they use cover crops, the greater the yield increases and cost savings that are reported by producers.”

The survey shows a majority of farmers are buying cover crop seed from cover crop seed companies and retailers.

“We are pleased to see farmers appreciate the expertise of cover crop seed companies, with 46% saying they buy from them and another 42% buying from retailers,” says Jane DeMarchi with ASTA. “Professionally produced cover crop seed is grown for seed from the start and has been selected, harvested, cleaned and tested for performance. The study shows farmers are using a range of cover crop seed and mixes to address their individual needs, with 46% paying $15 or under per acre.”

Of the 1,172 farmers who provided responses in the 2019-20 survey, 81% were commodity producers (corn, soybeans, wheat, cotton), and 19% categorized themselves as horticultural producers.

Following are some highlights from the survey.

Higher yields, lower costs

The previous five national cover crop surveys sponsored by SARE, CTIC and ASTA all reported yield boosts from cover crops, most notably in the drought year of 2012 — soybean yields were 11.6% improved following cover crops, and corn yields were 9.6% better.

In 2019, when wet early conditions prevailed across much of the corn and soybean regions, yield gains were more modest but still statistically significant. Following the use of cover crops, soybean yields improved 5% and corn yields increased 2% on average, while spring wheat yields improved 2.6%.

Many farmers reported economic benefits from cover crops beyond yield improvements. Of farmers growing corn, soybeans, spring wheat or cotton, the following percent had savings on production costs with fertilizers and/or herbicides:

  • Soybeans: 41% saved on herbicide costs and 41% on fertilizer costs
  • Corn: 39% saved on herbicide costs and 49% on fertilizer costs
  • Spring wheat: 32% saved on herbicide costs and 43% on fertilizer costs
  • Cotton: 71% saved on herbicide costs and 53% on fertilizer costs

While cover crop seed purchase and planting do represent an extra cost for farmers, most are finding ways to economize on cover crop seed costs. Whereas earlier surveys from 2012 and 2013 reported on a median cover crop seed cost of $25 per acre, most farmers reported paying less in 2019.

Of the responding farmers, 16% paid only $6 $10 per acre for cover crop seed, 27% paid $11 to $15 per acre, 20% paid $16 to $20 per acre, and 14% paid $21 to $25 per acre. Only about one-fourth paid $26 or more per acre, according to the report.

Planting green

Planting green refers to planting a cash crop such as corn, soybeans or cotton into a still-living cover crop, and then terminating it soon after with herbicides, a roller-crimper or other methods. In this year’s survey, 52% of farmers planted green into cover crops on at least some of their fields. In the 2016-17 report, 39% of respondents had planted green.

Of the farmers planting green:

  • 71% reported better weed control
  • 68% reported better soil moisture management, which is particularly valuable during a wet spring

The majority of farmers said levels of early-season diseases, slugs and voles — often feared as the potential downsides of planting green into cover crops — were about the same or better after planting green into cover crops. Though many farmers noted they did not have problems with voles, several pointed out challenges with cutworms when planting green.

The top two reasons farmers plant cover crops:

  1. Most use cover crops to improve soil structure or soil health.
  2. Many plant cover crops to improve weed management.

The majority of farmers responding to the survey said they plant cereal rye as a cover crop. Radishes are the second most popular cover crop. But when they are using a mix, radishes are the No. 1 most planted cover crop, followed closely by a rye mix. Half of respondents say they are increasing the number of crops in their cover crop mix.

For the full survey report, including past years’ survey reports, visit sare.org/covercropsurvey.

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Science News

NEWSARCHAEOLOGY

The oldest known grass beds from 200,000 years ago included insect repellents

The ancient bed remnants include fossilized grass, bug-repelling ash and aromatic leaves

South Africa’s Border Cave
South Africa’s Border Cave, shown here at its entrance, contains bits and pieces of the oldest known grass bedding, dating to around 200,000 years ago, researchers say.A. KRUGER

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By Bruce Bower

AUGUST 13, 2020 AT 2:00 PM

People living in southern Africa around 200,000 years ago not only slept on grass bedding but occasionally burned it, apparently to keep from going buggy.

Remnants of the oldest known grass bedding, discovered in South Africa’s Border Cave, lay on the ashes of previously burned bedding, say archaeologist Lyn Wadley of the University of the Witwatersrand in Johannesburg and her colleagues. Ash spread beneath bound bunches of grass may have been used to repel crawling, biting insects, which cannot easily move through fine powder, the researchers report in the Aug. 14 Science. Wadley’s team also found bits of burned wood in the bedding containing fragments of camphor leaves, an aromatic plant that can be used as a bug repellent.

Prior to this new find, the oldest plant bedding — mainly consisting of sedge leaves, ash and aromatic plants likely used to keep insects away — dated to around 77,000 years ago at South Africa’s Sibudu rock-shelter.

At Border Cave, chemical and microscopic analyses of excavated sediment showed that a series of beds had been assembled from grasses, such as Guinea grass and red grass. Guinea grass currently grows at Border Cave’s entrance. Bedding past its prime was likely burned in small fire pits, the researchers suspect. Remains of fire pits were found not far from Border Cave’s former grass beds.

Grass fragments uncovered in South African cave
Preserved grass fragments uncovered in a South African cave, left, are by far the oldest known examples of grass bedding, researchers say. Close-up images of those fragments taken by a scanning electron microscope, such as the one shown at right, helped to narrow down what type of grasses were used for bedding.L. WADLEY

Humans in southern Africa intentionally lit fires by around 1 million years ago (SN: 4/2/12). But Border Cave provides the first evidence that ancient grass bedding was burned on purpose.

Small, sharpened stones were also found among grass and ash remains, suggesting that people occasionally sat on cave bedding while making stone tools.

Questions or comments on this article? E-mail us at feedback@sciencenews.org

CITATIONS

L. Wadley et al. Fire and grass-bedding construction 200 thousand years ago at Border Cave, South Africa. Science. Vol. 369, August 14, 2020, p. 863. doi: 10.1126/science.abc7239.

Bruce Bower

About Bruce Bower

Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeolo

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Bug wars: Feds introduce Asian wasps to battle emerald ash borer outbreak in Lincoln area

Ash borer wasps

The Tetrastichus planipennisi wasp lays eggs in the larvae of the emerald ash borer.

  • Peter Salter

A piece of ash branch, infested with the emerald ash borer and injected with the eggs of the Tetrastichus planipennisi wasp, was attached to an ash tree at Platte River State Park last summer.

City tree crews discovered the first signs of emerald ash borer infestation in a tree near 37th and F streets.

One of the newest members of Lincoln’s insect family is a little wasp with a big name and no desire for human flesh.

But it can’t live without the emerald ash borer.

The Tetrastichus planipennisi is an underhanded killer, penetrating the bark of an infected ash tree with its ovipositor — the stinger on other species — to lay eggs in the larvae of the emerald ash borer.

“Then the eggs hatch,” said Dave Olson, a forest health specialist with the Nebraska Forest Service. “And they eat the ash borer from the inside-out.”

Its cousin, Oobius agrili, likes its borers even younger: It injects its own egg inside an ash borer egg, eventually hatching, growing and killing its host.

In both cases, the parasitic wasps mature — larvae, pupae, adulthood — then fly away, looking for more victims, continuing the cycle.

 Ash borer update: Some trees to get reprieve; replanting plans not taking root everywhere

And the brutality of this bug-eat-bug world is now being waged in Lincoln and nearby state parks, introduced to the area by the U.S. Department of Agriculture in an attempt to slow the spread of the emerald ash borer.

The Asian beetle, about the size of a cooked grain of rice, was first confirmed in North America in the early 2000s and has been eating its way west across the U.S. since, piling up massive damage.ADVERTISING

The insect had already killed tens of millions of ash trees — with an estimated value of $11 million — by the time it reached Nebraska, first confirmed in a Douglas County tree in 2016. It landed in Lancaster County in 2018, caught in a trap near Pioneers Park, and was discovered infesting trees in Lincoln last spring.

It’s a lethal little bug, and Lincoln’s estimated 65,000 public and private ash trees are vulnerable. The city has already started removing and replacing most of its 14,000 trees from parks, golf courses and along streets, and will attempt to prolong the lives of some with chemical treatments.

 Emerald ash borer found in Nebraska’s Saunders County

The stingless wasps were the federal government’s idea. The USDA’s Plant Protection and Quarantine program approached the state last year, and the Forest Service identified a handful of spots that could benefit from biocontrol: Pioneers Park, Mahoney and Platte River state parks and Fremont Lakes State Recreation Area.

A federal rearing lab in Michigan supplied nearly 20,000 wasps from three species and in various stages — Oobius agrili pupae, Tetrastichus planipennisi eggs, larvae and pupae, and Spathius galinae wasps.

In some cases, the lab delivers a Trojan tree limb — a branch cutting already infested with ash borer and injected with wasp larvae. Once in the field, the branch is attached to a tree that shows signs of the ash borer, and the adult wasps emerge from the cutting and start hunting in the host tree.

It’s too soon to see results, Shayne Galford, the USDA’s state plant health director for Nebraska and Kansas, said in an email. But officials will return to the release sites to introduce more wasps this year, and check for established populations in 2021. They could also add more sites, he said.

 ‘Each table is a small victory’ — How volunteers and salvage lumber are helping flood victims

The new weapon in the war on emerald ash borers won’t stop their spread, said Olson, with the state forest service. But it could crimp it.

“It’s not going to be a silver bullet. The real goal is to get these predators set up so in a few years the emerald ash borer has additional pressure on it.”

 In war against ash borer, a side skirmish erupts in east Lincoln

Reach the writer at 402-473-7254 or psalter@journalstar.com.

On Twitter @LJSPeterSalter View Comments84215

How to get ready for the emerald ash borer in the Lincoln area

Local

How to get ready for the emerald ash borer in the Lincoln area

  • Updated Feb 18, 2020

They found the first bug in August, in a treetop trap they set northwest of Pioneers Park.

Platte River floodwaters claim Rod and Gun Club cabin near Fremont
Annual Polar Plunge not so polar this time around

l

Penny

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JULY 20, 2020

Returning to farming’s roots in the battle against the ‘billion-dollar beetle’

by University of Arizona

Returning to farming's roots in the battle against the 'billion-dollar beetle'
Western corn rootworm larvae can devour the tips of corn roots, robbing the plants of nutrients and making them susceptible to falling over. Credit: Cyril Hertz, Lingfei Hu and Matthias Erb, University of Bern, Switzerland

Nicknamed the “billion-dollar beetle” for its enormous economic costs to growers in the United States each year, the western corn rootworm is one of the most devastating pests farmers face.https://3777ec3032f89ac36b1a5fe5c7568749.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.html

“They are quite insidious. They’re in the soil gnawing away at the roots and cutting off the terminal ends of the roots—the lifeblood of corn,” said Bruce Tabashnik, Regents Professor and head of the University of Arizona Department of Entomology. “And if they’re damaging enough, the corn plants actually fall over.”

Genetically modified crops have been an important tool in the battle against pests such as these, increasing yields while reducing farmers’ reliance on broad-spectrum insecticides that can be harmful to people and the environment.

Corn was genetically engineered to produce proteins from the bacterium Bacillus thuringiensis, or Bt, that kill rootworm larvae but are not toxic to humans or wildlife. The technology was introduced in 2003 and has helped keep the corn rootworm at bay, but the pest has begun to evolve resistance.

“So, now the efficacy of this technology is threatened and if farmers were to lose Bt corn, the western corn rootworm would become a billion-dollar pest again,” said Yves Carrière, a professor of entomology in the College of Agriculture and Life Sciences.

Crop Rotation in Mitigating Pest Resistance

Carrière is lead author of a study to be published in PNAS that evaluated the effectiveness of crop rotation in mitigating the damage caused by resistant corn rootworms. Tabashnik and colleagues from North Carolina State University, the University of California-Davis, McGill University and Stockholm University coauthored the study.

Crop rotation, the practice of growing different crops in the same field across seasons, has long been used for pest control. In 2016, the U.S. Environmental Protection Agency mandated crop rotation as a primary means of reducing the damage to Bt corn fields caused by resistant corn rootworms, but there have been limited scientific studies to support the efficacy of this tactic.https://googleads.g.doubleclick.net/pagead/ads?client=ca-pub-0536483524803400&output=html&h=280&slotname=5350699939&adk=2265749427&adf=625945176&w=750&fwrn=4&fwrnh=100&lmt=1595996918&rafmt=1&psa=1&guci=2.2.0.0.2.2.0.0&format=750×280&url=https%3A%2F%2Fphys.org%2Fnews%2F2020-07-farming-roots-billion-dollar-beetle.html&flash=0&fwr=0&rpe=1&resp_fmts=3&wgl=1&dt=1595996918602&bpp=11&bdt=88&idt=147&shv=r20200727&cbv=r20190131&ptt=9&saldr=aa&abxe=1&cookie=ID%3Dfd49ee1f356c7aad-2230268791c20026%3AT%3D1595996908%3AS%3DALNI_MZ__AIkhsEMsw1AjrlZUCXlh_wvFw&correlator=2622896222429&frm=20&pv=2&ga_vid=683244895.1595996911&ga_sid=1595996919&ga_hid=1573871060&ga_fc=0&iag=0&icsg=2271232&dssz=26&mdo=0&mso=0&u_tz=-300&u_his=2&u_java=0&u_h=1080&u_w=1920&u_ah=1040&u_aw=1920&u_cd=24&u_nplug=3&u_nmime=4&adx=447&ady=2184&biw=1903&bih=969&scr_x=0&scr_y=0&oid=3&pvsid=1003068873479674&pem=0&rx=0&eae=0&fc=896&brdim=0%2C0%2C0%2C0%2C1920%2C0%2C1920%2C1040%2C1920%2C969&vis=1&rsz=%7C%7CpeEbr%7C&abl=CS&pfx=0&fu=8320&bc=31&ifi=1&uci=a!1&btvi=1&fsb=1&xpc=7ptrOeJu1R&p=https%3A//phys.org&dtd=154

Carrière and his team rigorously tested this approach by analyzing six years of field data from 25 crop reporting districts in Illinois, Iowa and Minnesota—three states facing some of the most severe rootworm damage to Bt cornfields.

The results show that rotation works. By cycling different types of Bt corn and rotating corn with other crops, farmers greatly reduced rootworm damage.

Most notably, crop rotation was effective even in areas of Illinois and Iowa where rootworm resistance to corn and soybean rotation had been previously reported.

According to the study, crop rotation provides several other benefits as well, including increased yield, reductions in fertilizer use and better pest control across the board.

“Farmers have to diversify their Bt crops and rotate,” Carrière said. “Diversify the landscape and the use of pest control methods. No one technology is the silver bullet.”

Returning to farming's roots in the battle against the 'billion-dollar beetle'
Western corn rootworm beetle on corn tassels. Credit: Joseph L. Spencer, Illinois Natural History Survey, University of Illinois at Urbana-Champaign

A Multipronged Approach

Tabashnik relates the research back to UArizona’s work with the pink bollworm, in which researchers spearheaded a management program to suppress the pink bollworm’s resistance to Bt cotton.

“The key to eradicating pink bollworm in the U.S. was integrating Bt cotton with other control tactics,” Tabashnik said. “We succeeded, whereas this voracious invasive pest rapidly evolved resistance to Bt cotton in India, where the genetically engineered crop was used alone.”

In collaboration with cotton growers, UArizona scientists sustained the efficacy of Bt cotton against pink bollworm by establishing the “refuge strategy,” in which non-Bt crops are planted near Bt crops to allow survival of susceptible insects. The strategy has become the primary approach used worldwide to delay the adaptation of insect pests to genetically engineered crops.

Although farmers have used refuges to thwart the rootworm’s resistance to Bt corn, this strategy alone has proven insufficient against the pest.

“During the last decade, we have learned that refuges are often not sufficient to delay resistance in pests like the corn rootworm,” Carrière said. “It would be wise to diversify management tactics before such pests evolve resistance. This approach, called integrated pest management, is vital for preserving the benefits of biotechnology.”

Returning to Agricultural Roots

In many ways, the study reaffirms traditional agricultural knowledge.

“People have been rotating crops since the dawn of farming. The new agricultural technology we develop can only be sustained if we put it in the context of things we’ve known for thousands of years,” Tabashnik said. “If we just put it out there and forget what we’ve learned in terms of rotating crops, it won’t last.”

The authors emphasize that increasing crop rotation is essential for sustaining the economic and environmental benefits provided by rootworm-active Bt corn. During the six years of the study, the average percentage of corn rotated to other crops per state ranged from about 55-75%.

“This is one of the most important applications of Bt crops in the United States,” Carrière said. “If we lose this technology and we start using soil insecticides again, it’s going to have a big negative environmental impact.”


Explore furtherScientists offer recommendations for delaying resistance to Bt corn in western corn rootworm


More information: Crop rotation mitigates impacts of corn rootworm resistance to transgenic Bt corn, PNAS (2020). DOI: 10.1073/pnas.2003604117Journal information:Proceedings of the National Academy of SciencesProvided by University of Arizona

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science daily

Gene-editing protocol for whitefly pest opens door to control

Date:
April 23, 2020
Source:
Penn State
Summary:
Whiteflies are among the most important agricultural pests in the world, yet they have been difficult to genetically manipulate and control, in part, because of their small size. An international team of researchers has overcome this roadblock by developing a CRISPR/Cas9 gene-editing protocol that could lead to novel control methods for this devastating pest.
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Whiteflies are among the most important agricultural pests in the world, yet they have been difficult to genetically manipulate and control, in part, because of their small size. An international team of researchers has overcome this roadblock by developing a CRISPR/Cas9 gene-editing protocol that could lead to novel control methods for this devastating pest.

According to Jason Rasgon, professor of entomology and disease epidemiology, Penn State, whiteflies (Bemisia tabaci) feed on many types of crop plants, damaging them directly through feeding and indirectly by promoting the growth of fungi and by spreading viral diseases.

“We found a way to genetically modify these insects, and our technique paves the way not only for basic biological studies of this insect, but also for the development of potential genetic control strategies,” he said.

The team’s results appeared on April 21 in The CRISPR Journal.

The CRISPR/Cas9 system comprises a Cas9 enzyme, which acts as a pair of ‘molecular scissors’ that cuts DNA at a specific location on the genome so bits of DNA can be added or removed, and a guide RNA, that directs the Cas9 to the right part of the genome.

“Gene editing by CRISPR/Cas9 is usually performed by injecting the gene-editing complex into insect embryos, but the exceedingly small size of whitefly embryos and the high mortality of injected eggs makes this technically challenging,” said Rasgon. “ReMOT Control (Receptor-Mediated Ovary Transduction of Cargo), a specific type of CRISPR/Cas9 technique developed in my lab, circumvents the need to inject embryos. Instead, you inject the gene-editing complex which is fused to a small ovary-targeting molecule called BtKV, into adult females and the BtKV guides the complex into the ovaries.”

To explore the use of ReMOT Control in whiteflies, the team targeted the “white” gene, which is involved in eye color. When this gene is functioning normally, whiteflies have brown eyes, but when it is non-functional due to mutations, the insects is supposed to have white eyes. The team found that ReMOT Control generated mutations that resulted in juvenile insects with white eyes that turned red as they developed into adults.

“Tangentially, we learned a bit about eye color development,” said Rasgon. “We expected the eyes to remain white and were surprised when they turned red. Importantly, however, we found that the mutations we generated using ReMOT Control were passed on to offspring, which means that a change can be made that is inherited to future generations.”

Rasgon said the team hopes its proof-of-principle study will allow scientists to investigate the same strategy using genes that affect the ability for the insects to transmit viral pathogens of crop plants to help control the insects and protect crops.

“This technique can be used for any application where you want to delete any gene in whiteflies, for basic biology studies or for the development of potential genetic control strategies,” he said.


Story Source:

Materials provided by Penn State. Note: Content may be edited for style and length.


Journal Reference:

  1. Chan C. Heu, Francine M. McCullough, Junbo Luan, Jason L. Rasgon. CRISPR-Cas9-Based Genome Editing in the Silverleaf Whitefly (Bemisia tabaci). The CRISPR Journal, 2020; 3 (2): 89 DOI: 10.1089/crispr.2019.0067

Cite This Page:

Penn State. “Gene-editing protocol for whitefly pest opens door to control.” ScienceDaily. ScienceDaily, 23 April 2020. <www.sciencedaily.com/releases/2020/04/200423130410.htm>.

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Delta f perss

 

Adam-Famoso-01-DFP-BRobb Brad Robb
Dr. Adam Famoso, talks to rice growers about the latest breeding efforts from the scientists and researchers at the LSU AgCenter in Rayne, La., during its recent rice field day.

New LSU rice breeding strategies include genetic markers

Dr. Adam Famoso provides insight into what growers are learning about Provisia Rice System during its first year of commercial availability.

Brad Robb | Jul 23, 2018

The LSU AgCenter has a long history of rice breeding success. At its recent field day at the H. Rouse Caffey Rice Research Station in Rayne, La., area rice farmers heard the latest performance data on the Clearfield Rice Production System, the Provisia Rice System, and what growers can expect from both systems and their impact on the future U.S. rice production.

One presentation was given by Dr. Adam Famoso, who joined the staff of the H. Rouse Caffey Rice Research Station in May 2015. Famoso is not only developing breeding strategies for the station, he is also carrying the breeding program into the next generation of breeding technology, including the use of genetic markers.

He has begun incorporating DNA marker-based selection by genotyping the rice varieties of the future through DNA analysis prior to the standard field testing. “We are working to build upon the strong breeding foundation in place at the LSU AgCenter by integrating molecular tools to accelerate the release of the best varietal lines for our growers,” says Famoso.

Breeding Traits

Famoso provided some insight into what growers are learning about Provisia Rice System — the first herbicide-tolerant system released since the Clearfield Production System was released 15 years ago — during its first year of commercial availability.

“It always takes a few steps in the breeding process to increase the performance of the new herbicide-resistant varieties when the technology is being incorporated from unadapted material, as we work to get them to the point where our adapted varieties are today,” says Famoso.

“We have to look for specific traits in thousands of lines and select for things such as maturity, height, and grain quality to increase a variety’s commercial value to a producer. That’s what had to be done with PVL01.”

Despite being a little lower yielding than the varieties released under the Clearfield designation, PVL01 is exhibiting some excellent qualities like low chalk and a nice long grain.

“Similar to the Clearfield varieties when they were first released, we expected a little yield drag,” adds Famoso. “After 10 years of breeding though, the Clearfield varieties are the highest-yielding on the market today.”

Another Provisia

Famoso and the rest of the scientists have been analyzing data from another Provisia line, PVL108. It has improved characteristics over PVL01 like better milling and yield.

“In addition to having very low chalk, PVL108 has shown a 10 percent yield advantage over PVL01 in three years of statewide testing,” says Famoso. “That is pretty significant.”

PVL108 is maturing a week earlier than PVL01 — a trait which Louisiana rice producers prefer, especially now that hurricane season has begun. “The earlier we can get a rice variety to mature, the less risk our growers will have to assume toward the end of the year,” says Famoso.

Although longer-maturing varieties typically yield more, in the balance of all things, farmers in the line of fire from hurricanes know earlier is better.

While PVL108 has some yield and earliness advantages, it is 2 inches taller than PVL01. Shorter plant height is preferred to reduce the risk of lodging. PVL108 also has a shorter grain than PVL01.

“One positive aspect of PVL01 is its long grain, although PVL108 is classified as a long grain variety, its grain length is slightly shorter than PVL01,” explains Famoso.

Seed increase

In the interests of time, efforts are under way to begin the necessary seed increase and purification for PVL108. “We started with a seed increase in Puerto Rico over the winter. We brought back 50 pounds of seed and planted it on 5 acres at 10 pounds an acre here at the research station,” explains Famoso.

“If we decide to move forward with this variety, we should have a good bit of seed available for seed production next year, and in producers’ fields for the 2020 growing season.”

Famoso knows the disease resistance in PVL108 is not as active as it is in CL153, but there are some materials currently in early-stage testing that are showing not only an improvement in yield, but also a much-improved resistance to blast.

“It’s our intention to release a new variety every two to three years that will chip away at some of the limitations we are seeing in these current Provisia varieties,” adds Famoso. “I’d like to see them perform up to the levels of the Clearfield varieties as quickly as possible.”

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Science

Watch how battles with bats give moths their flashy tails

Bats and their prey are in a constant arms race. Whereas the winged mammals home in on insects with frighteningly accurate sonar, some of their prey—such as the tiger moth—fight back with sonar clicks and even jamming signals. Now, in a series of bat-moth skirmishes (above), scientists have shown how other moths create an “acoustic illusion,” with long wing-tails that fool bats into striking the wrong place. The finding helps explain why some moths have such showy tails, and it may also provide inspiration for drones of the future.

Moth tails vary from species to species: Some have big lobes at the bottom of the hindwing instead of a distinctive tail; others have just a short protrusion. Still others have long tails that are thin strands with twisted cuplike ends. In 2015, sensory ecologist Jesse Barber of Boise State University in Idaho and colleagues discovered that some silk moths use their tails to confuse bat predators. Now, graduate student Juliette Rubin has shown just what makes the tails such effective deterrents.

Working with three species of silk moths—luna, African moon, and polyphemus—Rubin shortened or cut off some of their hindwings and glued longer or differently shaped tails to others. She then tied the moths to a string hanging from the top of a large cage and released a big brown bat (Eptesicus fuscus) inside. She used high-speed cameras and microphones to record the ensuing fight.

Moths with no tails (such as polyphemus) were easy quarry for the bats, escaping only about 27% of the time, Rubin, Barber, and colleagues report today in Science Advances. But when Rubin enlarged the polyphemus hindwing lobe, twice as many escaped the bat’s sonar, or echolocation system.

Bats going after long-tailed African moon moths got a mouthful of tail 75% of the time as the moths flitted away. Shorten the tail, and the African moon moths escaped only 45% of the time. With no tail at all, that percentage dropped to 34%. When Rubin’s colleagues Chris Hamilton and Akito Kawahara at the Florida Museum of Natural History in Gainesville built a family tree of silk moths and their relatives, they realized that long tails had evolved independently several times. That’s further evidence that they are an important life-saving feature for these moths.

“The authors have demonstrated a powerful approach for understanding the diversity of moth shapes,” says Aaron Corcoran, an animal ecologist at Wake Forest University in Winston-Salem, North Carolina, who was not involved with the work. “There appear to be many different ways to trick a bat’s echolocation system.” The study also revealed how hard it was for bats to work around this deception, he adds. “The fact that the bats in the study never learned how to catch these moths, despite ample time to do so, shows how hard-wired this blind spot is in the bat’s perception.”

The findings could benefit other fields such as robotics, says Martin How, a sensory ecologist at the University of Bristol in the United Kingdom. Because the study examined the bat-moth dogfights at such a fine scale, the results could help engineers design the “bio-inspired technologies of the future,” he says, including deftly flying drones.

*Correction, 5 July, 1:45 p.m.: This article has been updated to reflect that although Juliette Rubin was the lead author of the paper, some of the work was done by other researchers.

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fall-armyworm-frontal-MER-563x744

‘Push-pull’ crop system to curb fall armyworms

Report

from EastAfrican

Published on 13 Feb 2018 View Original

In Summary
– Intercropping maize with drought-resistant greenleaf desmodium and planting Brachiaria grass on the farm’s edge helps curb fall armyworms.

Researchers have found intercropping maize with drought-resistant greenleaf desmodium and planting Brachiaria grass on the farm’s edge helps curb fall armyworms.

Desmodium and Brachiaria grass are high quality animal fodder plants.

The leguminous greenleaf desmodium becomes repellent, emitting a blend of compounds that help push armyworms away from maize while Brachiaria Mulato II grass around field edge produces chemicals attractive to the pests.

The International Centre of Insect Physiology and Ecology (Icipe) said that the “push-pull” crop system also promotes soil fertility and hinders the striga weed from attaching roots of cereal crops.

Icipe together with Rothamsted Research of Britain studied 250 maize farms that have adopted the push-pull method in western Kenya, eastern Uganda and northern Tanzania and found that the climate-adapted push-pull technology controls fall armyworm in smallholder farming systems in East Africa.

The method was initially developed for control of cereal stem borers and striga weed.

The scientists studied Kenya’s Bungoma, Busia, Siaya, Vihiga, Migori and Homa Bay sub Counties, Tarime district in Tanzania, Uganda’s Iganga, Bugiri ,Tororo and Bukedea districts.

Data on number of fall armyworm larvae on maize, percentage of maize plants damaged by larvae and grain yields was collected. Each farmer had a set of two plots, a climate-adapted push–pull and a maize monocrop.

There was 82.7 per cent reduction in number of fall armyworm larvae per plant and 86.7 per cent drop in plant damage per plot with push-pull systems. Grain yields were significantly higher, 2.7 times in systems plots.

“The farmers in the push-pull project reported that their fields were free of fall armyworm infestation while neighbouring monocrop plots were being ravaged by the pest,” said ICIPE’s Pull-Push Leader Prof Zeyaur Khan.

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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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