| Abstrakt: |
Rice is one basic food crop for billions of peoples around the world. Now a days it is becoming very difficult to feed the world's population due to the drastic reduction in the productivity of rice, mainly because of production constraints such as biotic and abiotic stress. Among biotic stresses, bacterial leaf blight (BLB) is a major devastating disease which causes drastic yield loss in rice caused by bacteria Xanthomonas oryzae pv. oryzae (Xoo). To overcome this problem, identification and development of resistant varieties play a vital role. In the present study, an attempt was made to phenotypically and genotypically characterize a set of 33 traditional rice varieties (TRVs) of Karnataka for BLB resistance and presence of corresponding resistance genes, respectively. Phenotypic screening was done by artificially inoculating rice genotypes with Xoo by clipping method. Following phenotyping, other than the check variety improved samba mahsuri, Kari bhattha was the only genotype that was found to be resistant to BLB. Further, 11 TRVs were recorded as moderately resistant with lesion length ranging from 5-15 cm, whereas 21 TRVs were found to be susceptible with a lesion length of 15 cm and above. Genotyping for the presence of ten BLB resistance genes was performed using linked SSR markers for the R genes. The results of genotyping study revealed that the four broad spectrum R genes conferring durable resistance to BLB that include Xa5, Xa13, Xa21 and Xa38 were present only in check variety Improved Samba Mahsuri. Among 33 traditional rice varieties evaluated, 17 varieties harbored 8 R genes, eight varieties had 7 R genes and nine varieties had a maximum of 9 R genes. Further, among ten BLB resistance genes studied, six genes that include Xa5, Xa1, Xa33, Xa7, Xa30 and Xa38 were present in all the 33 TRVs studied. [ABSTRACT FROM AUTHOR] |
