ABSTRACT
In the previous chapters, we have demonstrated biplot analyses of genotype-by-environment (GE) data (Chapter 5), genotype-by-trait data (Chapter 7), quantitative trait loci (QTL)-mapping data (Chapter 8), and diallel-cross data (Chapter 9). Another important and fascinating area of research related to plant breeding is genotype-by-pathogen interaction. Breeding for resistance to various diseases and pests has been a most important objective in most breeding programs, and an understanding of host genotype-by-pathogen strain or pest interaction for a given disease or pest is of vital importance for successful breeding.
Breeding for disease resistance is an important part of any plant-breeding project. Effective breeding for disease resistance relies on a good understanding of the host–pathogen relationships. This chapter demonstrates application of biplots in the analysis of host genotype-by-pathogen strain interactions using two contrasting datasets. The first dataset is on barley resistance to net blotch, which shows strong host genotype-by-pathogen strain specificities. In this scenario, the main effects of genotypes and strains are of little importance. It is the specific genotype-by-strain interaction that is important. The second dataset is on wheat resistance to Fusarium head blight (FHB), which shows no clear host–pathogen specificity. The analysis should, therefore, be concentrated on identifying the best resistant cultivars and the most virulent strains that differentiate the cultivars.
