The wheat crop in India is attacked by several diseases. Amongst, rusts (Puccinia spp) are prominent and causes substantial losses during epidemic years. Leaf rust is the most important widely distributed and frequently occurring diseases in the Indian sub-continent. It spreads both from southern and northern hills to the plains. Usually, life span of a wheat variety is shortened by the evolution of new virulent rust pathotypes. Therefore, development of wheat cultivate carrying diverse rust resistance genes with a broad range of effectiveness and their geographical deployment, depending on the race flora, is essential. Introgression by backcrossing method of the effective alien genes, viz. Lr19, Lr24, Lr28, Lr32 and Lr37 into well adapted commercial Indian bread wheat (Triticum aestivum L.) cultivars, which are highly susceptible to leaf rust was the principal objective of the study. The Secale cereals segment carrying linked genes Sr31 Lr26 Yr9 Pm8 was also introduced into six popular Indian cultivars, namely, HD2329, WH147, Lok-1, HUW234, C306 and N15439 and the improved lines were recombined with three leaf rust resistance genes, Lr24, Lr28, and Lr32. Some of the backcross lines carrying alien genes have been released for commercial cultivation in India.

S-3-4 H. S. Dhaliwal¹, P. Chhuneja², K. Singh² (¹Indian Institute of Technology, Roorkee, ²Punjab Agricultural University, India)
Wild germplasm of wheat -a mine of variability for food and nutritional security-

The genetic bases for resistance against various wheat diseases among bread wheat cultivars of India is very narrow. Breeding wheat for superior bread making quality and high nutritional quality has not been seriously taken up. To ensure adequate food and nutritional security for the ever-increasing population not only more wheat grains with higher nutritional quality have to be produced from less area but also the production at higher level of productivity is to be sustained against biotic and abiotic stresses. Germplasm of related wild progenitor and no-progenitor Triticum, and Aegilops species constitute a very rich reservoir of useful variability for breeding for high nutritional quality and resistance against biotic and abiotic stresses. Under a series of collaborative USDA funded projects the germplasm of various Triticum and Aegilops species was collected, maintained and screened under field and laboratories conditions for resistance against diverse pathotypes of various diseases of wheat including rusts, Karnal bunt, powdery mildew and cereal cyst nematode. High level of useful variability was discovered for resistance against various diseases and other traits both within and among species. About 20 genes with different mechanisms for resistance against various diseases were transferred from eight species through interspecific hybridization with or without induced homoeologous chromosome paring, molecular cytogenetics and molecular markers. Suppression of resistance was found to be ubiquitous phenomenon in interspecific crosses. The Ph¹ gene of Aegilops speltoides was found to be highly satisfactory for induced homoeologous chromosome pairing. Transfer of high molecular weight glutenin subunits from wild Triticum species into T. durum not only increased the protein content but also improved the sedimentation value of the recipient line. Pyramiding of leaf rust resistance genes using marker assisted selection in the elite wheat cultivars is in progress. Variability for three to fold higher level of iron and zinc content in the grains of wild A, D and S genome species compared to that of durum and bread wheat cultivars has been found which can be used for overcoming the hidden hunger for the micronutrients in half of the world population. Some of the introgression derivatives with useful variability have been registered with the National Bureau of Plant Genetic Resources, New Delhi for use at the international level. Recent advances of molecular breeding, comparative and functional genomics, gene cloning and genetic transformation can be used for reducing linkage drag, gene discovery and allele mining for efficient and effective utilization of the useful variability for wheat improvement