![]() ![]() oryzae ( Xoo) is also a destructive disease of rice in many rice growing countries of the world. This disease caused by Xanthomonas oryzae pv. Improved varieties are essentially needed that combine high grain yield with submergence tolerance along with in-built resistance to major diseases and insect pests.Īmong the biotic stresses, bacterial leaf blight causes considerable yield loss in this ecology. Rice cultivation in rainfed lowland ecosystem is associated with major biotic and abiotic stresses that reduce the productivity. In India, rainfed lowland rice occupies around 16 million hectares area of which 92% is located in the eastern region of the country. ![]() Globally, rice is cultivated in 163.2 million hectares of which approximately 45% area is under rainfed ecology with low productivity due to various abiotic and biotic stresses 1. The crop is cultivated in diverse agro-ecology starting from high elevation to below sea level. Rice grain is a source of carbohydrate, protein, specific oils, dietary fibre, vitamins, many minerals and other disease-fighting phyto-compounds for which, also known as golden cereal. Rice, the queen of cereals is life for millions of global population. ![]() The pyramided lines were similar to the recurrent parent in 14 morpho-quality traits. The pyramided lines also exhibited submergence tolerance for 14 days. Bioassay of the 18 pyramided lines containing BB resistance genes was conducted against different Xoo strains conferred very high levels of resistance to the predominant isolates. ![]() Amongst the pyramided lines, 3 lines were homozygous for all the target genes. Eighteen BC 3F 2 plants were obtained by selfing the selected BC 3F 1 line. Amongst backcross derivatives, the plant carrying five target genes and maximum recurrent parent genome content was selected in each generation and hybridized with recipient parent. Background selection in plants carrying the target genes was performed by using 100 simple sequence repeat markers. Foreground selection for the five target genes was performed using closely linked markers and tracked in each backcross generations. Four BB resistance genes viz., Xa4, xa5, xa13, Xa21 and Sub1 QTL for submergence tolerance were incorporated into the mega variety. Marker-assisted backcross breeding was followed to develop submergence tolerant and durable BB resistant variety in the background of popular cultivar ‘Swarna’. Bacterial blight (BB) disease and submergence due to flash flood are the two major constraints for achieving higher yield from rainfed lowland rice. ![]()
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