Development of high-protein quality leafy maize materials for forage breeding

The development of high-protein quality leafy maize materials holds promise in maize breeding specialised for forage and silage. In this study, leafy maize materials were developed using conventional breeding and the application of simple sequence repeats (SSR) markers. Results from phenotyping 20 maize lines indicated that PM3, PM7, PM8, PM9, PM10, PM12, PM14, and PM17 have average grain yields equivalent to the check CML161 and significantly higher than CML165. Using primers phi112 and phi057, the opaque-2 gene was found in 10 lines. The protein content of the lines ranged from 8-11%, making them suitable for breeding quality protein maize (QPM). Notably, PM7, PM8, PM10, PM12, PM14, PM15, PM16, and PM17 have a quality index (QI) above the minimum of 0.8 and are considered QPM lines. Our findings confirmed that lines PM7, PM8, PM10, PM12, and PM17 could initially be evaluated as the most promising for QPM development. By crossing lines carrying the opaque-2 gene with the leafy maize line (Leafy5), 11 leafy materials (LM) were successfully developed. Specifically, LM6 and LM10, with 10-12 leaves above the uppermost ear and good agronomic traits, were selected as segregating populations for background selection using SSR markers to identify the opaque-2 gene for developing QPM leafy maize in the future.