Diverse and stable male sterile tropical Asian maize inbred lines provide strategic opportunities for hybrid development

Cytoplasmic Male Sterility, a maternally inherited trait which suppresses the production of viable pollen, eliminates the need for detasseling of females in hybrid maize seed production. A set of 88 diverse elite CIMMYT Asia maize inbred lines converted to CMS-C using a temperate donor, were evaluated for stable per se performance for grain yield, male sterility and Turcicum Leaf Blight resistance. Performances of CMS maize hybrids of varied genetic backgrounds across diverse environments -- seasons, years, agroecologies, countries, abiotic- and biotic stresses -- established a stable and robust diversification process which included the identification of potential maintainers and restorers that will benefit researchers, the seed industry and farmers. While multiple CMS hybrids showed a range of yield performances comparable to non-CMS checks, we report on a distinct 9.9% yield advantage of a CMS hybrid compared to its isogenic non-CMS counterpart through a head-to-head analysis. From implications in enhancing global genetic gains to addressing issues of labour availability and rising wages, the technology offers opportunities for intellectual property protection and region-wide taming of tropical Asian maize germplasm diversity by imposing a heterotic discipline.