Effectiveness of One Cycle of Phenotype-Based Backcross Breeding for Resistance to Late Wilt Disease in Maize (Zea mays L.)

摘要

Late Wilt Disease (LWD) caused by Harpophora maydis is one of the serious biotic constraints of maize leading to considerable yield losses. Host-plant resistance breeding is widely accepted as the ideal, eco-friendly and economical strategy to minimize losses attributable to LWD. Backcross selection is widely used method for introgressing LWD resistance into elite agronomic genetic background. LWD tolerant donor parent, CV138811 and susceptible recurrent parent, CV143587 were used to develop BC_1F_1plants at Monsanto breeding station. The BC_1F_1 plants were screened for responses to LWD infection under artificial inoculation condition. Forty three BC_1F_1 plants significantly different from susceptible parent but similar to resistant parent for LWD tolerance were selected. BC_1F_2 families derived from 43 selected BC_1F_1 plants differed significantly. Forty nine per cent of BC_1F_2 families and 40 per cent of BC_1F_2 plants transgressed resistant parent for LWD tolerance. Among the transgressedBC_1F_2 families, four best families homogeneous for LWD tolerance with narrow range and low Phenotypic Coefficient of Variation (PCV) were selected. These results provided adequate evidence for the effectiveness of one-cycle of phenotype-based back cross selection.