Barley and wheat resistance genes for Fusarium Head Blight

STENGLEIN S.A. & ROGERS W.J.

Management of fungal plant pathogens

CAB International

Lugar: Oxford, UK; Año: 2010; p. 78 - 91

The genetic control of resistance to Fusarium head blight (FHB) in barley and wheat is reviewed. This disease, which can reach epidemic proportions under certain climatic conditions, is caused by various Fusarium species and detrimentally affects grain yield and quality, resulting in important economic losses in both crops. Furthermore, FHB infection poses a serious threat to human and animal health, due to the presence of mycotoxins, principal amongst which are the trichothecenes, of which deoxynivalenol and its derivatives appear to be the most important. Marker-based mapping studies have identified numerous QTL for FHB resistance, located on all the chromosomes of both species. Only a relatively small number of these can be consistently detected over a wide range of different environments and genetic backgrounds. Nonetheless, where genetic effects have been characterised they have been shown to be mainly additive in nature, meaning that the accumulation of several QTL factors in a single line ought to be effective in achieving raised levels of resistance. Indeed, marker-assisted selection has been directly shown to be feasible for some QTL. A number of QTL for FHB resistance are associated with other agronomic characters, such as heading date, flowering time and plant height. In some cases, QTL alleles favourable for resistance are detrimentally associated with alleles for these characters, although there appear to be sufficiently large numbers of QTL for resistance acting independently of these characters to imply that reasonable genetic gains for resistance ought to be achievable in the future, without prejudicing other agronomic characteristics. While most studies in barley have addressed Type I resistance (initial infection) and in wheat Type II (spread between spikelets) or a combination of both Type I and Type II, more recent studies have addressed other Types of resistance, such as Type III (effects on kernel size and characteristics), Type IV (yield tolerance) and Type V (decomposition or non-accumulation of mycotoxins such as deoxynivalenol). Besides identifying additional QTL, these latter studies are offering insights into the mechanisms of the different Types of resistance observed, in some cases blurring the distinctions between them. Other prospects for FHB resistance improvement, additional to those offered by marker-assisted selection, are also discussed