Plant Pest Interactions: How Soybean Aphids Trick Soybean Plant Defences

An Adult Soybean Aphid © Ho Jung Yoo, Purdue University (via Wikimedia Commons)

Following on from a previous blog on the interactions between soybean plants and soybean pests,  new research on soybean (Glycine max) responses to the soybean aphid (Aphis glycines) published in Molecular Plant-Microbe Interactions has revealed some of the complex and fascinating interactions between pests and their plant hosts.  This recent research led by Dr Gustavo Macintosh and Matthew Studham from Iowa State University has shown that soybean aphids can suppress the natural plant defense response of soybean plants to the aphids through the activation of what is known as an antagonistic decoy response. For example, the aphid will induce a plant defense that is not particularly effective against the pest (the ‘decoy’ defense) while suppressing the effective defense in order for it to continue feeding on the plant.  It has further been found that aphids can actively suppress the effective defence responses of the plant while at the same time ‘hijacking’ the plant metabolism to improve the nutritional value of the plant for their own benefit. Soybean aphids do this by inducing asparagine synthase transcripts which improve the nutritional content of the phloem sap from which they feed. Continue reading

The Soybean Gene: Scientists Discover the Key to Nematode Resistant Soybeans

Scanning electron micrograph of a soybean cyst nematode and egg © Ethan Hein via Flickr (License CC-BY-NC-SA 2.0)

Soybean (Glycine max) is an important crop that provides a sustainable source of protein and oil worldwide in countries such as the USA, Brazil, Argentina, India and many African countries, including Nigeria, South Africa and Uganda. The soybean cyst nematode Heterodera glycines is a microscopic roundworm that feeds on the roots of soybean and is a major constraint to soybean production. This nematode causes more than US$1 billion in yield losses annually in the United States alone, making it the most economically important pathogen on soybean. For over 50 years the planting of resistant cultivars and crop rotation have been the main management strategy for this pathogen, and only a few resistant plant types are used due to undesirable traits in other resistant varieties of soybean.  Moreover, the increase in virulent populations of the nematode on most known resistant plant sources coupled with the very limited knowledge of soybean resistance mechanism makes the development of new approaches for control of soybean cyst nematode a necessity. Continue reading