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Plant Health

Genetic patterns associated with plant immunity

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Biologist discovered that repeats in genetic patterns associated with plant immunity may cause its immune system to misbehave.

Genomic information from plants can be used to enhance agricultural production and improve food security in a sustainable manner. Through better understanding of the relationship between a plant’s genetic information and the resulting behaviour, improved crops with better traits (resistance to diseases, tolerance to drought, etc.) can be developed. This can be achieved through cross pollinating plants with selected traits to produce a hybrid with the desired characteristics.

A research team led by Prof Eunyoung CHAE from the Department of Biological Sciences, NUS has discovered that in selective plant breeding, the genes responsible for providing defence responses against powdery mildew (RPW8) in the Arabidopsis thaliana plant, when duplicated as multiple copies in the genome, can misregulate immune receptors to trigger autoimmunity in hybrid plants. This can cause the premature gradual death of the foliage in these hybrids, known as hybrid necrosis.

The researchers applied a technique known as the genome-wide association mapping study (GWAS) to the model plant Arabidopsis thaliana in this research. GWAS is an important tool to identify genetic variation in plants which are associated with a particular trait. It allows the researchers to identify Single Nucleotide Polymorphisms (SNPs) which mark the causal natural variation in the genome responsible for growth-immunity trade-off. These SNPs are like postal codes showing the genetic information that are associated with autoimmune symptoms in plants. The SNPs were found to be located adjacent to a multi-gene cluster which is known to confer resistance to powdery mildew (a fungal disease that affects a wide range of plants). The team found that having multiple copies of this set of genetic codes (RPW8) in Arabidopsis thaliana is detrimental as it triggers its autoimmunity mechanism even in the absence of pathogens.

Prof Chae said, “The plant Arabidopsis thaliana used in our study belongs to the Brassicaceae family, and the family members include vegetables such as broccoli, kale, cabbage, mustard and bok choy. Our team is currently assessing the variability of the plant immune system, particularly on the powdery mildew resistance gene clusters in this family, and if the variability is associated with heightened resistance and/or trade-off between immunity and growth.”

Read the paper: PLOS GENETICS

Article source: National University of Singapore

Image credit: PLOS GENETICS

To avoid cassava disease, Tanzanian farmers can plant certain varieties in certain seasons

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A nutty-flavored, starchy root vegetable, cassava (also known as yuca) is one of the most drought-resistant crops and is a major source of calories and carbs for people in developing countries, serving as the primary food for more than 800 million people. However, the crop is vulnerable to virus diseases, such as cassava brown streak disease (CBSD), which poses the biggest threat to production in East and Central Africa. To understand how cassava virus disease builds up over repeated planting cycles, a team of Tanzania-based scientists conducted experiments in coastal Tanzania, where there are two planting seasons.

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Plant Health: prioritising the fight against 20 plant pests on the EU

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The EU has published a list of 20 regulated quarantine pests qualifying as priority pests, including Xylella fastidiosa, the Japanesebeetle, the Asian long-horned beetle, Citrus greening and Citrus Black Spot, whose economic, environmental and social impact on EU’s territory is the most severe. Member States will have to launch information campaigns to the public, do annual surveys, prepare contingency plans, simulation exercises, and action plans for the eradication of these pests.

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Insect or virus? How plants know

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Most plants have plenty of enemies, from insects and other grazing creatures to various diseases, droughts and many other stressors.
Plants respond to injuries or illnesses by initiating various defense measures. But a viral infection requires a completely different response than desiccation, of course.
To know more about its attacker, the cell relies on mechanical and chemical signals.

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molecular plant-microbe interactions

Nodulation connected to higher resistance against powdery mildew in legumes

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Scientists have long known that nodulation is important to plant health. Nodulation occurs when nodules, which form on the roots of plants (primarily legumes), form a symbiotic relationship with nitrogen-fixing bacteria that deliver nutrients to the plant. This process is a key part of sustainable agriculture and makes legumes an important source of protein for much of the world. However, recent research shows that nodulation might positively impact the plant’s microbiome in other ways.

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