Identification of genetic markers for lodging resistance in wheat

Abstract

Wheat breeders have traditionally increased lodging resistance by shortening crop height; however the scope for further reducing crop height appears to be limited because more extreme dwarfing genes have been shown to be incompatible with high yields. Lodging either occurs through buckling of the stem base (stem lodging) or through overturning of the root anchorage system (root lodging).

Lodging resistance could therefore be increased by strengthening the stem base and anchorage system. However these traits are not currently assessed by breeders because they are too time consuming to measure. This project therefore aimed to provide UK breeders with new molecular tools to help them breed new wheat varieties with greater lodging resistance by increasing stem and anchorage strength.

Two breeding populations from Nickerson-Advanta were analysed across three seasons. There was significant genetic variation within plant breeder's germplasm for the traits which determine stem strength and anchorage strength, and for height. Genetic markers were found for several of the key traits that, with further development and validation, could be used to facilitate trait selection.

Some of the genetic markers for increasing lodging resistance were associated with lower yields. It was shown that by selecting the correct combination of genetic markers it would be possible to increase lodging resistance by the equivalent of three varietal lodging resistance scores (standing powers) without reducing yield. A different combination of genetic markers would increase yield without increasing lodging risk.

The project identified several height genes within UK elite wheat varieties in addition to the 'standard' semi-dwarf genes. If reliable genetic markers can be identified for these height genes then plant breeders could select the most appropriate parents for crossing in order to produce new varieties of optimal height. The project also discovered that some height genes are more responsive to plant growth regulators (PGRs) than others which should pave the way for predicting varietal responses to PGRs and so allowing them to be targeted more accurately.

One of the genetic markers which identified a major yield gene was shown to increase both grain and straw yields by about 0.5 t/ha each, and did not affect rooting at depth. This discovery indicates that breeders can improve yield and stem strength simultaneously. Straw is also an increasingly valuable co-product for biomass and potentially for liquid biofuel production.