Screening of different rice (Oryza sativa L.) varieties for genetic diversity and bacterial blight resistance gene

Rice (Oryza sativa L.) is one of the most important crop feeding about 2.5 billion people around the world and it is a major source of nutrition. Asian countries are the main producers as well as consumers of the rice. Oryza sativa and Oryza glaberrima are the two common cultivated rice species. Oryza sativa is cultivated in Asian regions, while Oryza glaberrima is cultivated in African region. Rice is the second most important food crop in Pakistan. More than 40% of the world's rice crop is lost annually due to biotic stress such as pests, insects, weeds and pathogens. This study was carried out to identify bacterial blight resistance genes (Xa13 and Xa21) in Pakistani, Indian, Japanese, Taiwanese and Philippine's rice varieties. Investigation of genetic diversity among rice varieties was also carried out by total seed proteins profiling using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Protein bands of size ranging from 10 kDa to 125.8 kDa were observed. Genetic similarity values ranged from 0.22 to 1.00 and cluster analysis divided all the varieties into five groups. For molecular identification of Xa13 and Xa21 genes fragment, sequence-tagged-site (STS) markers were used. Xa13 gene fragment was present in 30 varieties and Xa21 gene fragment was present in 43 varieties. Genetic diversity was present among rice varieties. The information about the genetic diversity of studied rice varieties will be very useful in identification and selection of suitable parents for use in breeding programs to develop unique germplasm that complement existing varieties regarding high yield and resistance to bacterial leaf blight disease.