Genetic analysis of two wheat cultivars, ‘Sonalika’ and ‘WL 711’ for reaction to leaf rust (Puccinia recondita)

Summary

Genetic analysis for leaf rust reaction of two widely adapted cultivars, ‘Sonalika’ and ‘WL 711’, has been done using 21 near isogenic Lr lines and rust culture IL004 — avirulent on the two cultivars and all the Lr lines used. The segregation pattern in the F₂ generation indicated the presence of a recessive gene in ‘Sonalika’ and of a dominant gene in ‘WL 711’. These genes in cultivars ‘Sonalika’ and ‘WL 711’ have been identified as Lr 11 and Lr 13, respectively. Gene Lr 13 is no longer effective in ‘WL 711’ but it continues to give field resistance in the backgrounds of ‘Chris’, ‘Prelude’ and ‘Thatcher’. There has been no significant change in the virulence spectrum of the leaf rust pathogen in India with the release of ‘WL 711’. High susceptibility of ‘WL 711’ seems to be due to the evolution of more aggressive forms of the pathogen to this cultivar. The gene Lr 11, which behaves as a recessive in ‘Sonalika’, was effective against leaf rust when this cultivar was released. The high susceptibility of ‘Sonalika’ is probably due to an increase in the frequency of race 77 virulent on Lr 11. Lr 11 has shown a dominance reversal in the background of ‘Sonalika’. Present results suggest that interaction of resistance genes with the background genotype must be studied for their effective use in breeding programme.