Association Mapping for Bacterial Leaf Blight Resistance in Rice Oryza sativa L

Abstract

Globally, rice is considered a major food crop for the people. Over 3.5 billion people rely on rice as their staple food and source of daily calories . Rice productivity is adversely impacted by numerous biotic and abiotic stresses. However, rice production is constrained by considerable number of disease of fungal, bacterial and viral origin. newlineBacterial leaf blight caused by Xanthomonas oryzae pv. oryzae is one of the most devastating diseases of rice in Tropical Asia. It can cause severe yield loss by 20-50 per cent and as high as 80 per cent and even 100 per cent under very severe conditions. In management of this disease, the most economical and effective approach is cultivating resistant varieties. Due to cultivation of genetically uniform varieties over large scale imposed high selection pressure on the pathogen populations which makes them vulnerable to biotic and abiotic stresses. It can be controlled by (i) chemical against the pathogen (ii) genetic modification of the host plant to resist the disease (iii) alteration of the environment to make it unfavourable for the development of the disease or for the growth of the pathogen. In a crop like rice which is grown on a large scale under varied agro climatic conditions, it is not possible to make such alterations in the environment as would be unfavourable for development of disease. Chemical control of the disease has been tried in many countries but has not been effective. Therefore, identification of new resistance genes and alleles from diverse germplasm has now been accepted as the best and most economical way to control the disease and to avoid environmental hazards due to excessive use of chemicals. newlineBased on the above considerations, the present investigation entitled Association Mapping for Baterial Leaf Blight Resistance in rice (Oryza sativa L.) was carried out during Kharif2014 and 2015 at Agricultural Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi (U.P.). newlineIn the present study, the genetic diversity of bacterial leaf blight resistance gene and genome wide association study to identify major BLB resistance R gene(s) was carried out in 484 diverse indigenous collections of rice germplasm. newline