Cloning and characterization of a novel maize leaf area modifier and its effects across elite germplasm

Abstract Plant architecture is a crucial component of maize productivity. Tailoring architectural component traits like leaf area and angle can increase productivity by promoting deeper light penetration into the canopy and better resource utilization. Novel genetic variants can increase the rate of gain for optimized plant architecture. Here, we map a moderate-effect mutation denoted reduced leaf area1 (rdla1) to the RAGGED5 (RGD5) locus and characterize it as a transposon insertion allele. Mutant leaf area reductions were most extreme in mid-upper canopy positions. Photosynthetic gas exchange rates were not significantly impacted in rdla1 relative to wild-type, indicating that mutant leaf structure, but not function, is altered. Functional annotations of RDLA1 were supported by metabolite profiles suggesting a role in cuticular wax biosynthesis. Introgression of the rdla1 allele into 27 commercially relevant genetic backgrounds identified differences in effect size across genotypes, revealing modifier effects that could serve as targets for modulating plant architecture. Competing Interest Statement The authors have declared no competing interest. Abbreviations - Anet - net CO2 assimilation - CER - ECERIFERUM - Ci, intercellular - CO2 concentration, E, transpiration - ExPVP - Expired Plant Variety Protection - gs - stomatal conductance to water - iWUE - intrinsic water-use efficiency - rdla1 - reduced leaf area1 - SLA - specific leaf area