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Disease immune wheat, pests threat, annual climate change impact, aflatoxins

By Nicola Cottam

- Last updated on GMT

Scientists find that removing disease-sensitive genes from wheat crops can potentially reduce losses by as much as 80%
Scientists find that removing disease-sensitive genes from wheat crops can potentially reduce losses by as much as 80%

Related tags Crops

Disease-resistant wheat that can up yields developed, global pest problem is a cause for concern, annual effects of climate change are identified, methods to reduce aflatoxin contamination investigated.

Disease-resistant wheat cultivar can increase yields

Breeding or genetically modifying crops to increase resistance to common diseases can have negative knock-on effects on productivity, particularly where crop yields are concerned, but researchers at Curtain University in Australia have developed a disease resistant wheat cultivar with no yield losses and, in some cases, increased yields.

Large wheat cultivar trials were used to test whether lines sensitive or insensitive to three disease provoking proteins (or necrotrophic effectors) from the Pyrenophora tritici-repentis​ and Parastagonospora nodorum​ fungi differed in yield when subjected to natural disease and stress pressures in the West Australian wheat belt.

Cultivars with disease-sensitivity genes were compared to those without the gene and results showed the cultivars lacking the gene showed no yield loss and in some instances increased yields in the presence of disease.

The team concluded that eliminating the sensitivity gene would provoke only minimal associated risks and would be a safe and straightforward strategy for improving disease resistance.

Professor Richard Oliver, at the University, said:  “Removing disease-sensitive genes from wheat crops could potentially reduce losses by as much as 80%. For the first time, our technology allows for a steady and sustained improvement in disease resistance without affecting the farmer’s pocket. In addition, breeders are able to devote more time and resources to breeding for yield, as well as for rust and frost resistance.”

Source: Plant Pathology
DOI: 10.1111/ppa.12191
“Absence of detectable yield penalty associated with insensitivity to Pleosporales necrotrophic effectors in wheat grown in the West Australian wheat belt”
Authors: R. Oliver, J. Lichtenzveig, K. C. Tan, O. Waters, K. Rybak, J. Lawrence, T. Friesen, P. Burgess

Global pest threat underestimated

The amount of crop pests in developing countries has been hugely underestimated and could pose a major threat to food producing nations, such as India and China, researchers claim.

The Biotechnology and Biological Sciences Research Council (BBSRC) has funded a study by Dr Dan Bebber and Professor Sarah Gurr at the University of Exeter that has analyzed known distributions of almost 2,000 crop-destroying organisms in 195 countries in an attempt to assess global factors effecting the distribution of crop pests.

Whereas developed countries have the scientific and technical means to accurately record pest rates, the same cannot be said for developing countries where levels have been considerably underestimated, they found.

As a result, many developing countries could be harboring an unknown number of crop pests and diseases – thought to be in their hundreds – based on their current levels of agricultural productivity, the researchers said.

"Crop pests pose a significant and growing threat to food security, but their geographical distributions are poorly understood. If every country had US-levels of per capita GDP, then on average countries would be reporting more than 200 additional pests and diseases. This suggests that enhanced investment in pest observations will reveal the hidden threat of crop pests and pathogens, as well as bring into focus the opportunity to lose less of the crop by appropriate pest control. The first step to solving crop losses is to identify the pests responsible,"Dr Bebber said.

Source: New Phytologist
DOI: 10.1111/nph.12722
“Economic and physical determinants of the global distributions of crop pests and pathogens”
Authors: DP. Bebber, T. Holmes, D. Smith and SJ. Gurr

Year on year climate change impact

The most important climatic factors determining crop growth, development, and yield are rainfall, solar radiation and temperature. Each element impacts yields in a different way and understanding their relationship is essential to forecasting crop production and improving management techniques to deal with climate change, researchers say.

Numerous studies have attempted to quantify the crop–climate relationship and many have shown that yields from a variety of crops were linearly related to seasonal crop water use or available water at planting.

Climatic factors influencing crop yields are often correlated with each other where, for example, rainfall increases soil water, but is also associated with decreases in solar radiation and daytime temperature. In humid regions, there is high rainfall but limited solar radiation, with the latter the dominant feature determining yield.

Ultimately it is the combination of management techniques and weather conditions that determine wheat yield. These have increased over the years due to technological improvements such as adoption of new cultivars and increase in nitrogen application and other management options. However, using statistical approaches, such as fitting and filtering, the effects of technological improvements can be approximately eliminated.

Source: International Journal of Climatology
DOI: 10.1002/joc.3704
“Year patterns of climate impact on wheat yields”
Authors: Qiang Yu, Longhui Li, Qunying Luo, Derek Eamus, Shouhua Xu, Chao Chen, Enli Wang, Jiandong Liu, David C. Nielsen

Non-biological remediation of aflatoxins

The presence of aflatoxins in cereal crops is a major bugbear for farmers and a lot of time and money has been spent on developing technology to detect and eradicate them. These include methods for the detoxification and management of aflatoxins in post-harvest agricultural crops using non-biological techniques.

The United Nations Food and Agricultural Organisation (FAO) estimates 25% of the world’s food supply is affected by aflatoxins, which equates to a significant global health risk. The International Agency for Research on Cancer (IARC) has classified aflatoxins as established carcinogens to humans and contamination has also been linked to diseases such as hepatitis B and C, as well as various lung and immune system diseases.

UV radiation increases aflatoxin susceptibility to degradation and thereby reducing harmful effects, while adding binders or sequestering agents to animal feed reduces intestinal absorption of toxins. However, the physical removal or separation of aflatoxin-contaminated crops – based on size, shape, colour and visible fungal growth - is still thought to be the most effective non-biological strategy for reducing aflatoxins. 

Source: Journal of the Science of Food and Agriculture

“A recent review of non-biological remediation of aflatoxin-contaminated crops”
DOI: 10.1002/jsfa.6520
Authors: Erika D Womack, Ashli E Brown, Darrell L Sparks

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