Increasing seed yields by the targeted modulation of brassinosteroids (based at Rothamsted Research)

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Seeds constitute the main propagule for plant growth and at the same time are the most importantagricultural product, accounting for at least 70% of the world's food supply. With rising populationand diminishing agricultural land, it is increasingly urgent to improve crop yields. Increasing seed sizeand number in seed crop species are important routes to achieving this goal, and improving foodsecurity. In situations where seeds are the most important part of the crop, e.g. oil-seed rape, wheat,maize, and rice, the best way to increase yield is to produce plants that have a higher number of seedswith no concomitant decrease in seed size or quality. In plants, such as oilseeds, where seeds areproduced in pods, seed number per pod is often positively correlated with seed yield. In addition,there is also a positive correlation between oil content in seeds and seed number per pod.Brassinosteroids control a large number of agronomically important traits including seed yield,flowering time, and stress tolerance. Over-expression of brassinosteriod biosynthetic or signallinggenes in Arabidopsis and rice have resulted in concomitant increases in seed yield. However, in manycases constitutive over-expression of these genes led to undesirable negative effects on plant growthand yield. This implies that changes in brassinosteroid synthesis or signalling can cause a combinationof positive and negative effects on traits that are of interest. Therefore, the use of tissue specificpromoters represents a strategy for increasing crop yield by modulating the level of brassinosteroidsand harnessing their role in plant development.The project will focus on introducing selected brassinosteroid-related genes into Arabidopsis underthe control of distinct tissue-specific promoters and investigating the subsequent effects on seed yieldtraits. Specifically, we will identify genes that increase the number of ovules in a plant leading to anincreased number of seed per pod. We will then test the ability of these introduced genes to increaseseed yield overall.The project will use a combination of molecular, developmental, and cell biological techniques andprovide training in the disciplines of plant genetics, genomics as well as bioinformatic, statistical, andmicroscopy techniques.