Annual Research & Review in Biology

Wheat (Triticum spp) is a crop of global significance and occupies a premier place among cereals. Due to its high nutritive value and huge acreage devoted for cultivation of wheat, it is a staple food supplying approximately 20% of total food calories. Although wheat has a wide range of climatic adaptability, it is usually affected by many biotic factors the most devastating of which are the rust diseases. All the three species of rusts viz. stem (black) rust (Puccinia gramims); leaf (brown) rust (P. triticina) and stripe (yellow) rust (P. striiformis) infect wheat crop. Yellow and leaf rusts cause enormous reduction in grain weight and yield. Both usually occurs in cooler areas when temperature ranges between 10-21°C. Different rust races are evolving and a total of 49 races of leaf rust and 22 of stripe rust identified. The wheat cultivars become susceptible to rusts due to their narrow genetic base and the rapid rate of evolution of the pathogen.  In order to sustain wheat production, use of disease resistant varieties is economical and efficient with resource poor farmers. The Indian wheat breeding programmes have also designated 49 and 67 genes for resistance to stripe and leaf rusts of wheat. Rust resistance genes most prevalent in Indian wheat varieties are Lr1, Lr3, Lr10, Lr13, Lr19, Lr23, Lr24, Lr26, Lr28, Lr34 for leaf rust, YrA, Yr2, Yr9, Yr18, Yr 27 for stripe rust. So the ultimate objective of the wheat breeding is to have improved better yielding, resistant cultivars with combined resistance through pyramiding especially those Lr/Yr genes which act against important races of leaf and yellow rusts.