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Field days show Ugandan farmers hope in disease-resistant varieties

By Allison Floyd
University of Georgia, Peanut & Mycotoxin Innovation Lab

Planting an unimproved variety of peanut in Uganda was a recipe for disaster this year. Groundnut rosette disease (GRD), an aphid-borne virus that causes mottling and affects much of sub-Saharan Africa, took 80% to 100% of the yield in some fields planted with a traditional variety.

The difficult season made farmers even more interested in two recent field-day events held in Uganda, where they could see the results coming from fields planted with improved varieties resistant to GRD.

Farmers check out peanut-growing guides at one of two recent Field Day trainings in Uganda.

One woman, a farmer named Adong Christine borrowed $7,000 from a bank and planted 20 acres with a local variety. At the end of the season, she harvested just two bags of peanuts (from a potential 400 bags) and could not repay the loan.

“There had been an outcry of big losses as most of the capital were borrowed from loan institutions. This event showcasing improved groundnut varieties therefore was timely as it restored hopes and enhanced adoption,” organizers said.

David Okello, the head of Uganda’s national groundnut research program and a leading scientist on PMIL’s breeding project, is behind many of the varieties. Based at the National Semi-Arid Resources Research Institute (NaSARRI) in Serere District, Okello works to create varieties that are high yielding, resistant to drought and GRD, and to educate farmers about practices that will give them more success with their peanut crop.

Peanuts are a traditional crop in Uganda and much of sub-Saharan Africa, are high-protein and valuable as a cash crop. Still, GRD is a persistent problem that stunts the growth of otherwise healthy plants and can destroy a crop if the disease strikes early enough in the season before flowering.

A woman farmer picks up some bags of seed at Field Days in the Nwoya District of Uganda. At the end of a particularly bad season for disease, many farmers made the investment to buy small bags of improved seed.

At one of two field days, 61 farmers, researchers and representatives of local government visited a 5.6-acre plot planted with three varieties bred for their resistance to GRD and leaf-spot, Serenut 9T (Aber), Serenut 14R and Serenut 5R. While participants could see for themselves the success of the varieties, farmers in the Loyo Kwo group, who are using the new varieties, explained their agronomic practices, where they get seed and how NaSARRI trainings helped improve their results.

“Heart breaking and sad testimonies came from the farmers growing local varieties,” Okello said. “The Loyo Kwo group members, on the other hand, were boasting of bumper harvests, higher income and improved livelihoods that they are experiencing from adopting the improved groundnut varieties,” Okello  said

Uganda Field DaysLeoora Okidi (centre) shows her approval of the high yield of Serenut 11T, an improved variety during a Field Day in August 2017 in the Kiteny Pader District of Uganda.

 

Farmers were able to buy small packs of .5 kg to 3 kg., and the NaSARRI team delivered 45 kgs of Serenut 8R (Achieng), a large-seeded red variety that had been previously promised.

In a second field day, farmers spent part of a religious holiday – the Assumption of the Virgin Mary to Heaven – visiting test plots, learning about improved production practices and visiting a farm where the owner planted Serenut 5R and Serenut 11T alongside the local Red Beauty variety.

Uganda Field Days crowdA crowd of farmers fan out over a field at a recent Field Days event comparing the yield and disease resistance of improved lines and varieties over the traditional, unimproved types, which have been ravaged by rosette disease this year.

 

The farmer, Leonora Okidi, planted 2 of her 5 acres with an improved variety, and the other 3 acres with the local variety. She abandoned the local variety after the first weeding since most of the plants had been severely attacked by the rosette virus.

In a good year, she is able to feed and educate her 11 own children and support 25 others from her groundnut operation, which is part of a women-led group called Pur Lonyo or “Farming is Wealth,” she said.

Okidi first connected with Okello through her son, who he mentored in his diploma and bachelor’s degree studies and still supervises in his current master’s degree studies. She offered land to host demonstration plots and participatory variety trials and co-funded the operations using her family labour.

“The superiority of our improved lines and varieties over her local varieties caught her attention and (Okidi) quickly adopted these improved varieties and has become a model research farmer in the village,” Okello said. “Through this effort our improved varieties adoption rates has increased and we are closely working with her women group to upscale these successes, improve their livelihoods and increase varieties adoption.”

– Published Sept. 1, 2017

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icipe logo

This issue of the icipe e-bulletin includes, amongst others, an excellent article on ‘Invasive species in Africa‘ by Dr. Segenet Kelemu, Director General, icipe  and on the invasive fall armyworm, Spodoptera frujiperda, by IAPPS East Africa Regional Coordinator, Dr. Tadele Tefera.

To view the bulletin click on the url below:

Click to view: icipe e-bulletin – Volume 7, Issue No. 2, 2017 (pdf)

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SE farm press

peanut-mature-green-leaves-field.JPG

Some peanut plants pass ‘memory’ of stress to next generation

Several studies of seed quality, seedling development, and vigor conducted by researchers at the University of Florida suggest that a “memory” of stress events in plants can be passed on to the next generation.

Kelly Arquette, Diane Rowland, Barry Tillman | Apr 18, 2017

For as long as crops have been domesticated, farmers have been selecting seed from the best performing plants; based primarily on their yield and relative performance. In some cases, a plant may experience stress during the season, whether from disease, drought, or insects.

Many times that plant will recover and still produce a decent yield, and possibly provide seed for planting the following year. It’s a system that has worked relatively well for a long time. But this system depends on the idea that if a plant experiences stress and survives, it won’t pass a memory of the stress on to its offspring. Farmers and researchers have made the assumption that the impacts of stress on a plant remain in the current generation and don’t make an imprint into the next generation. But recent research suggests that this might not be true.

Several studies of seed quality, seedling development, and vigor conducted by researchers at the University of Florida suggest that a “memory” of stress events in plants can be passed on to the next generation. In these studies, some varieties of peanut, for example, TUFRunner ‘511’ showed an increased rate of establishment and root growth when their parents had experienced a mild water stress, even when the next-generation seedlings themselves were well-watered.

Figure 1: Peanut root bioassay for early germination and root establishment for seed produced from parent plants that had experienced a mild drought stress during the season and for seed from parents that had not experienced any stress. The left hand panel clearly shows faster and more extensive root growth in offspring from stressed parents over a 12 day span (DAP = Days After Planting). Photo credit: Kelly Racette.

However, other varieties (C7616) displayed the opposite trend; seedlings had improved establishment and root growth when their parents had been well-watered. To complicate matters even further, a third set of varieties, including the Spanish-type variety, COC041, showed no evidence of stress memory in their offspring at all.

The presence of either a positive or negative memory in crop plants could have big implications for seed production. For example, if exposing parent plants to some degree of stress increased seed quality of the next generation, through improved germination and establishment, it may be useful to produce seed under mildly stressful conditions for these varieties. On the other hand, growing varieties that have poor seedling performance from stressed parent plants would require more careful management for seed production to get the best quality seed.

Before recommendations can be refined based on generational stress memory for the production of seed peanuts, further research is being conducted to find out which varieties of peanut display this “memory” and what other impacts stress could have on seed quality.

Currently, studies are being done on other Spanish- and runner-type varieties, like FloRun ‘107’ and New Mexico Valencia C. This additional information is critical to “fine tune” the ideal conditions for each variety during seed production to maximize the quality of seed essential for optimal germination and stand establishment. This research also extends and highlights how important optimal crop management is because decisions within a season could be impacting the next generation.

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Delta f perss

Western Corn Rootworm adults Purdue Extension Entomology – Purdue University
The western corn rootworm was first classified as a corn pest in the 1860s. Shown here are adults.

Fighting world hunger: Researchers use nuclear methods to study pest resistance in corn plants

Expertise, resources found at the University of Missouri allow researchers to study pest-resistance in corn that could help sustain projected 9 billion global population.

Jeff Sossaman | Mar 10, 2017

Developing corn varieties that are resistant to pests is vital to sustain the estimated 9 billion global population by 2050.

Now, researchers at the University of Missouri, using advanced nuclear methods, have determined the mechanisms corn plants use to combat the western corn rootworm, a major pest threatening the growth of the vital food source.

Scientists believe that using the knowledge gained from these cutting-edge studies could help crop breeders in developing new resistant lines of corn and make significant strides toward solving global food shortages.

“The western corn rootworm is a voracious pest,” said Richard Ferrieri, a research professor in the MU Interdisciplinary Plant Group, and an investigator at the MU Research Reactor (MURR).

“Rootworm larvae hatch in the soil during late spring and immediately begin feeding on the crop’s root system. Mild damage to the root system can hinder water and nutrient uptake, threatening plant fitness, while more severe damage can result in the plant falling over.”

Breeding corn that can fight these pests is a promising alternative. Ferrieri, and his international team of researchers, including scientists from the University of Bern in Switzerland, Brookhaven National Laboratory in New York and the U.S. Department of Agriculture, used radioisotopes to trace essential nutrients and hormones as they moved through live corn plants. In a series of tests, the team injected radioisotope tracers in healthy and rootworm-infested corn plants.

AUXIN

“For some time, we’ve known that auxin, a powerful plant hormone, is involved in stimulating new root growth,” Ferrieri said. “Our target was to follow auxin’s biosynthesis and movement in both healthy and stressed plants and determine how it contributes to this process.”

By tagging auxin with a radioactive tracer, the researchers were able to use a medical diagnostic imaging tool callED positron emission tomography, or PET imaging, to “watch” the movement of auxin in living plant roots in real time.

Similarly, they attached a radioactive tracer to an amino acid called glutamine that is important in controlling auxin chemistry, and observed the pathways the corn plants used to transport glutamine and how it influenced auxin biosynthesis.

The researchers found that auxin is tightly regulated at the root tissue level where rootworms are feeding. The study also revealed that auxin biosynthesis is vital to root regrowth and involves highly specific biochemical pathways that are influenced by the rootworm and triggered by glutamine metabolism.

“This work has revealed several new insights about root regrowth in crops that can fend off a rootworm attack,” Ferrieri said. “Our observations suggest that improving glutamine utilization could be a good place to start for crop breeding programs or for engineering rootworm-resistant corn for a growing global population.”

MURR

Ferrieri’s work highlights the capabilities of the MURR, a crucial component to research at the university for more than 40 years. Operating 6.5 days a week, 52 weeks a year, scientists from across the campus use the 10-megawatt facility to not only provide crucial radioisotopes for clinical settings globally, but also to carbon date artifacts, improve medical diagnostic tools and prevent illness.

MURR also is home to a PETrace cyclotron that is used to produced other radioisotopes for medical diagnostic imaging.

The study, “Dynamic Precision Phenotyping Reveals Mechanism of Crop Tolerance to Root Herbivory,” was published in Plant Physiology.

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New York Times

Photo

Cherry tomatoes. Researchers found that domesticated tomatoes like these were less resistant to whiteflies than currant tomatoes, a wild species. Credit Dean Fosdick/Associated Press

Whiteflies are the scourge of many farms, damaging tomatoes, peppers, eggplants and other crops. Now, researchers in Britain report that a species of wild tomato is more resistant to the pest than its commercial counterparts.

The wild type, the currant tomato, is closely related to domestic varieties, “so we could crossbreed to introduce the resistance,” said Thomas McDaniel, a biologist and doctoral student at Newcastle University in England and a co-author of the study, published in the journal Agronomy for Sustainable Development. “Another method would be genetic engineering, if we identified the genes.”

The researchers studied Trialeurodes vaporariorum, a species of whitefly that often attacks tomatoes grown in greenhouses. Whiteflies damage tomato plants by extracting the plant’s sap, which contains vital nutrients; by leaving a sticky substance on the plant’s surface that attracts mold; and by transmitting viruses through their saliva.

But currant tomatoes have some sort of mechanism, yet to be understood, that repels whiteflies. “They seemed to move away every time they tried to sample the sap,” Mr. McDaniel said.

The wild plants also produce a chemical reaction that causes the plant sap to gum up the whitefly’s feeding tube.

Growers use a parasitic wasp to control whiteflies. The wasp lays its eggs on young whiteflies, which are eaten by hatching larvae. The treatment is expensive and laborious. As an alternative, farmers use chemical pesticides, but some have been linked to declines in bee populations.

“Genetic diversity is very, very low in domestic crops, so introducing these genes that we’ve lost along the way is probably quite important,” Mr. McDaniel said.

Continue reading the main story

 

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PiercesDiseasePierce’s disease on grape

sharpshooterSharpshooter

UCDavis
Newly identified enzyme may be the culprit in Pierce’s disease grapevine damage
January 12, 2016

Printable version

http://news.ucdavis.edu/search/printable_news.lasso?id=11389&table=news

An enzyme appears to enable Xyllela fastidiosa bacteria to infect grapevines with Pierce’s disease, causing serious leaf damage. UC Davis plant scientists have identified an enzyme that appears to play a key role in the insect-transmitted bacterial infection of grapevines with Pierce’s disease, which annually costs California’s grape and wine industries more than $100 million.
The researchers hope that the discovery, which runs counter to existing theories, will lead to new diagnostics and potential treatments for Pierce’s disease. Their findings are reported in Scientific Reports, an online journal of the Nature Publishing Group.
“With a bacterial disease — much like cancer — if you understand how the virulent form spreads, you can better control or remove it, ” said Abhaya Dandekar, a professor of plant sciences and senior author on the study.
“We anticipate that this discovery could open new ways to think about dealing with Pierce’s disease and highlight other areas of immune response, in general, that haven’t yet been considered,” he said.
About Pierce’s disease
Pierce’s disease, first identified in the 1890s, is caused by the bacterium Xylella fastidiosa and is characterized by yellowed and browning leaves that eventually drop from the vine. The disease is transmitted from vine to vine by small, winged insects called sharpshooters.
Pierce’s disease is established in Northern California, where it is transmitted by the blue-green sharpshooter, which lives near rivers and streams. The disease became a serious threat to California agriculture in 1996 when the glassywinged sharpshooter — another Pierce’s disease carrier native to the Southwest — was discovered in the Temecula Valley of Southern California.
How infection progresses
It’s been known for a number of years that when Xyllela fastidiosa invades a grapevine, it produces a biofilm or gel in the xylem — the vascular tissue that transports water and some nutrients throughout the vine.
Scientists have theorized that this biofilm damages the vine by clogging up the xylem, preventing the flow of water to the leaves. That theory seemed to explain the yellowing of the leaf edges and eventual death of the leaf tissue.
But not all of the evidence stacked up to fit that theory, Dandekar said. For example a heavy accumulation of Xyllela fastidiosa in grapevine leaves was not always accompanied by severe disease symptoms in leaves. And, in some infected grapevines as well as other host plants, the leaves showed severe symptoms but the xylem had very little blockage.
So Dandekar and colleagues set out to investigate an alternative mechanism by which Xyllela fastidiosa might be wreaking havoc with the vine’s physiology.
Secrets of the “secretome”
The research team began by analyzing the bacteria’s secretome — the entire collection of enzymes and other proteins secreted by a disease-causing agent like Xyllela fastidiosa during the infection process. Such secreted proteins are known to play key roles in triggering many plant diseases.
The resulting data indicated that an enzyme, which the researchers named LesA, was quite abundant during Xyllela fastidiosa infections and shared characteristics with similar enzymes known to be capable of breaking down plant cell walls.
The researchers went on to confirm their suspicions by demonstrating that a mutant strain of Xyllela fastidiosa bacteria — with a specific gene knocked out, or inactivated — lacked the ability to cause infection in grapevines.
“The LesA enzyme has the ability to move through cell membranes, equipping the Xyllela fastidiosa bacteria to invade the grapevine and to live in its xylem tissues, where it feeds on fatlike compounds called lipids,” Dandekar says.
In this way, the LesA enzyme triggers the process that causes the typical Pierce’s disease leaf damage — a process completely unrelated to the xylem blockage and water stress that had previously been thought to cause the symptomatic leaf damage.
The research for the newly published study was conducted by Rafael Nascimento and Hossein Gouran, both graduate students in Dandekar’s laboratory. Dandekar said that his research team plans to move forward with Pierce’s disease research in hopes of developing ways to counteract the disease.

Funding for the newly published study was provided by the Pierce’s Disease Board of the California Department of Food and Agriculture.
Additional information:
• Related: Fused genes tackle deadly Pierce’s disease in grapevines
• Related: UC Davis cracks the walnut genome
• Related: Springtime for wheat starts with a gene that ‘sees’ light
Media contact(s):
• Abhaya Dandekar, Plant Sciences, (530) 752-7784, amdandekar@ucdavis.edu
• Pat Bailey, UC Davis News Service, (530) 752-9843, pjbailey@ucdavis.edu

Provided by:

Grahame Jackson
24 Alt street
Queens Park
NSW 2022
Australia

Phone: +612 9387 8030
Mobile: +61 412 994 206
Skype: gvhjackson

www.pestnet.orgwww.pestnet.org

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crd-logo
Released: 26-Apr-2015 7:00 PM EDT
Source Newsroom: Cardiff University

Newswise — Scientists may have uncovered a natural way of avoiding the use of pesticides and helping save plants from attack by recreating a natural insect repellent.
Scientists from Cardiff University and Rothamsted Research have, for the first time, created tiny molecules which mirror a natural occurring smell known to repel insects.
The scientists were able to make similar smelling insect repellent molecules, by providing the enzyme, ((S)-germacrene D synthase), which creates the smell, with alternative substrate molecules.
The effectiveness of the smell or perfume to function as an insect repellent was tested.
The team found that the smells repelled insects but in one case a reversal of behaviour – an attractant – was observed which raises the prospect of being able to develop a trap-and-kill device.
“We know that many organisms use smell to interact with members of the same species and to locate hosts of food or to avoid attack from parasites,” according to Professor Rudolf Allemann from Cardiff University’s School of Chemistry, who led the research.
“However, the difficulty is that scientifically smell molecules are often extremely volatile, chemically unstable and expensive to re-create. This means that, until now, progress has been extremely slow in recreating smells that are similar to the original.
“Through the power of novel biochemical techniques we have been able to make insect repellent smell molecules which are structurally different but functionally similar to the original,” he added.
Pesticides are toxic by design and are used widely to kill, reduce or repel insects, weeds, rodents, fungi or other organisms that can threaten public health and the economy.
Many concerns have been raised on the potential dangers to humans and the impact on the environment and local ecosystem.
Professor John Pickett, FRS from Rothamsted Research said: “This is a breakthrough in rational design of smells and provides a novel way of producing a smell with different properties and potentially better ones than the original but at the same time preserving the original activity.
“By using alternative substrates for the enzymes involved in the ligand biosynthesis (biosynthesis of the smell) we can create the appropriate chemical space to reproduce, with a different molecular structure, the activity of the original smell.”
The team hope that their research could provide a new way of designing and developing small smell molecules which would be otherwise be too difficult to produce by usual scientific and commercial methods.

Notes:
Touchet et al., Novel olfactory ligands via terpene synthases (DOI: 10.1039/c5cc01814e) was funded by the BBSRC and published in the journal Chemical Communications.
Further information or to arrange media interview, please contact:
Chris Jones
Communications and Marketing
Cardiff University
Tel: 029 20 874731
E-mail: jonesc83@cardiff.ac.uk
Cardiff University
Cardiff University is recognized in independent government assessments as one of Britain’s leading teaching and research universities and is a member of the Russell Group of the UK’s most research intensive universities. Among its academic staff are two Nobel Laureates, including the winner of the 2007 Nobel Prize for Medicine, University Chancellor Professor Sir Martin Evans. Founded by Royal Charter in 1883, today the University combines impressive modern facilities and a dynamic approach to teaching and research. The University’s breadth of expertise encompasses: the College of Arts, Humanities and Social Sciences; the College of Biomedical and Life Sciences; and the College of Physical Sciences, along with a longstanding commitment to lifelong learning. Cardiff’s four flagship Research Institutes are offering radical new approaches to cancer stem cells, catalysis, neurosciences and mental health and sustainable places.

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