Genetic basis of winter oilseed rape resistance to the cabbage stem flea beetle (PhD)
Aims and objectives
Cabbage stem flea beetle (CSFB) is a major pest of winter oilseed rape (OSR) in the UK. The pest also infests other brassica crops, including field vegetables and mustards.
Adult CSFB lay eggs that develop into larvae and burrow into petioles. Over winter these migrate into the main stem, often causing arrest of the shoot apex. If the plant cannot maintain growth and inflorescence production in the presence of the CSFB larvae, the yield from that plant will be lost.
CSFB was managed by neonicotinoid seed treatments. Such treatments are no longer authorised for use in OSR. The remaining control method, spraying with pyrethroid insecticides, is also threatened by increasing CSFB resistance. New technologies for controlling CSFB damage are, therefore, fundamentally important.
Considerable variation has been observed in OSR response to larval lodging. This variation can include yield-preserving developmental responses, such as growth in girth around the larvae and outgrowth of axillary buds. Such responses involve the plant hormone auxin, which makes it a strong candidate for investigations.
Dramatic variation has also been observed among Sinapis alba and Brassica juncea varieties used in mustard production, suggesting the tolerance mechanism in these species is similar.
The aim of this project is to identify the precise mechanisms by which OSR and mustards resist CSFB larvae. The project also aims to identify germplasm, markers and genes associated with desirable traits that breeders can use to produce CSFB tolerant varieties of OSR for the UK market.
Better understanding the variation in tolerance to CSFB larvae will help breeders identify and incorporate desirable traits. It will also allow geneticists to discover the genetic basis of these traits. The latter knowledge can be used to design molecular markers for marker assisted selection (MAS). MAS can be particularly useful for traits only visible in the latter stages of plant development or where infestation/infection cannot be guaranteed in trials.