Genetic diversity of leaf rust resistance in Indian wheats

Investigations were conducted on 58 Indian wheats for assessing the extent of genetic diversity for leaf rust resistnace. Seedling studies of these wheats had indicated that the genetic basis of resistnace was due to 9 Lr genes while the adult plant resistance studies showed as many as 18 distinct groups. Seedling testings of these genotypes displayed the maximum preponderance of Lr26, Lr34, Lr13 and Lr23 genes and all of them have become susceptible to the newly evolved pathotypes of leaf rust barring Lr34. Therefore there was an urgent necessity to mobilize the highly effective resistance genes Lr9, Lr19, Lr24 and Lr28 in breeding programmes.. Lr34, partial adult plant resistance gene which is invariably associated with durable resistance, confers a high degree of adult plant resistance in combination with other seedling resistance genes in these studies. Therefore a data base of adult plant resistance sources must be characterised in terms of the number and the nature of resistance genes to breed for durable resistance.