Analysis of Digenic Epistatic and QTL × Environment Interactions for Resistance to Banded Leaf and Sheath Blight in Maize (Zea mays)

Maize banded leaf and sheath blight (BLSB) due to Rhizoctonia solani Kühn, is an increasing problem in maize production areas, particularly in China and Southeast of Asian. A genetic map containing 146 simple sequence repeat (SSR) markers and 229 F2 plants derived from the cross R 15 (resistant) × Ye 478 (susceptible) were used in this study. QTL were characterized in a population of 229 F2:4 lines derived from selfing the F2 plants and were evaluated with two replications at two environments. QTL mapping analysis of disease resistance index of banded leaf and sheath blight (BLSB) in a F2: 4 population was performed with QTL Mapper 2.0 software. Twelve pairs of distinctly digenic epistatic QTL including a total of seventeen QTL were detected and distributed on seven chromosomes (2, 3, 4, 6, 7, 9 & 10). QTL main effects, epistatic effects, and QTL × environment (QE) interactions effects were predicted. Less than 20% of single effects, for identified QTL were significant at 5% level, most of which were dominance effects and additive × dominance epistatic interactions effects. There are few QTL with significantly QE interactions effects and they were mainly interactions between aa and environment. The information about QTL epistatic and QE interactions will facilitate marker-assisted (MAS) selection for BLSB resistance breeding programs in maize.