Development of banded leaf and sheath blight-resistant maize (Zea mays L.) hybrids through introgression of wild progenitor alleles

Abstract

Banded leaf and sheath blight (BLSB), caused by Rhizoctonia solani, is a major constraint in maize (Zea mays L.) production across tropical Asia, especially during the Kharif season. Due to the absence of effective resistance in cultivated maize, the wild progenitor Zea mays ssp. parviglumis was utilized to develop 14 stable introgression lines (ILs) in diverse maize genetic backgrounds from 2017 to 2021. Artificial inoculation trials conducted during Kharif 2021 and 2022 evaluated BLSB resistance in ILs, parental lines, and teosinte. A hybrid derived from two selected ILs-{(LM 14 × Zea mays ssp. parviglumis)///LM 14-⊗x-x-x-f} × {(LM 13 × Zea mays ssp. parviglumis)///LM 13}-⊗x-x-x-f}demonstrated moderate resistance to BLSB, with a disease score of 4.5. The female parent showed moderate resistance (4.5), while the male parent was moderately susceptible (6.7). Although none of the ILs matched the resistance level of teosinte (4.2), they exhibited significantly lower disease severity than their recurrent parental lines. This study underscores the potential of wild genetic resources for improving BLSB resistance in maize and lays a foundation for sustainable disease management.