Study of association between morphological traits and QTLs governing sheath blight resistance in rice (Oryza sativa L.)

Rice sheath blight is one of the most serious diseases of rice. In the current study, the relationship between morphological traits and sheath blight resistance was investigated by using 1545 recombinant inbred lines. Correlation analysis showed that culm angle, flag leaf angle, flag leaf length and plant height were significantly correlated with sheath blight resistance. Genome-wide association studies revealed that a gene controlling culm angle (TAC1), three quantitative trait loci (QTL) governing plant height (qPHT1–1), penultimate leaf angle (qPLA-1) and days to 50% flowering (qDFF-7) were found to be adjacent to the regions of qS69, qSBR1–1 and qSB7, the QTLs conferring sheath blight resistance. Except for these cases, no QTL underlying other traits was detected near the chromosomal region associated with sheath blight resistance. The results concluded that the morphological traits were not the main factors responsible for the sheath blight resistance but had some indirect influence to evade infection of the pathogen. An efficient approach in resistance breeding for sheath blight would be to pyramid major QTLs for sheath blight resistance and select those morphological traits that favour resistant reaction.