|XING, JUNJIE - Hunan Hybrid Rice Research Center|
|CORRELL, JAMES - University Of Arkansas|
|YUAN, LONGPING - Hunan Hybrid Rice Research Center|
|DENG, HUANGFENG - Hunan Hybrid Rice Research Center|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2015
Publication Date: 10/19/2015
Citation: Xing, J., Jia, M.H., Correll, J.C., Yuan, L., Deng, H., Jia, Y. 2015. Confirming and identifying new loci for rice blast disease resistance using magnaporthe oryzae field isolates in the US. Crop Science. 55:2620-2627. doi: 10.2135/cropsci2015.02.0077.
Interpretive Summary: Quantitative trait loci (QTL) in rice play important roles in controlling rice blast disease. Blast resistance QTL are commonly identified using phenotypic data from replicated field plot experiments. However, identified resistance QTL often are not reliable due to errors contributed by uncontrolled field environments. In the present study, using a controlled greenhouse method, six resistance QTL contributing 5.37% to 39.18% of phenotypic variation were identified with a mapping population derived from a cross of two U.S. adapted rice varieties, Lemont and Jasmine 85. Among them, three resistance QTL have been previously reported with different blast races, and the remaining three were not previously reported in this cross. This study demonstrated that resistance QTL identified under the controlled environment are reliable, and DNA markers closely linked to the resistance QTL are useful for breeding for improved blast resistance with marker assisted selection.
Technical Abstract: Quantitative trait loci (QTL) in rice play important roles in controlling rice blast disease. In the present study, 10 field isolates of the races IA1, IB1, IB17, and IC1 of U.S. rice blast fungus Magnaporthe oryzae collected in 1996 and 2009 were used to identify blast resistance QTL with a recombinant inbred line (RIL) population consisting of 227 F7 individuals derived from the cross of Lemont with Jasmine 85. Jasmine 85 is an indica variety that is moderately resistant, and Lemont is a tropical japonica variety that is susceptible to rice blast. Disease reactions of the parents and RILs were evaluated under greenhouse conditions. A total of six resistance QTL, qBLR8, qBLR10-1, qBLR10-2, qBLR10-3, qBLR12-1, and qBLR12-2, were identified on chromosomes 8, 10, and 12, respectively. Phenotypic variation, conditioned by these six resistance QTL, ranged from 5.37% to 39.18%. Among them, qBLR12-1 and qBLR12-2 provided the strongest resistance to the newest isolates of the most virulent race IA1 of M. oryzae. Three of these resistance QTL have been identified using different blast isolates in a previous study. However, BLR10-1, qBLR10-1, qBLR10-2, and qBLR10-3 have not been previously found in this cross. These confirmed and new resistance QTL will be useful for the development of rice cultivars with improved effective resistance to rice blast via a marker assisted selection (MAS) approach.