Stable Carbon Isotope Discrimination Is under Genetic Control in the C4 Species Maize with Several Genomic Regions Influencing Trait Expression

Abstract

Abstract In plants with C4 photosynthesis, physiological mechanisms underlying variation in stable carbon isotope discrimination (Ɗ13C) are largely unknown, and genetic components influencing Ɗ13C have not been described. We analyzed a maize (Zea mays) introgression library derived from two elite parents to investigate whether Ɗ13C is under genetic control in this C4 species. High-density genotyping with the Illumina MaizeSNP50 Bead Chip was used for a detailed structural characterization of 89 introgression lines. Phenotypic analyses were conducted in the field and in the greenhouse for kernel Ɗ13C as well as plant developmental and photosynthesis-related traits. Highly heritable significant genetic variation for Ɗ13C was detected under field and greenhouse conditions. For several introgression library lines, Ɗ13C values consistently differed from the recurrent parent within and across the two phenotyping platforms. Ɗ13C was significantly associated with 22 out of 164 analyzed genomic regions, indicating a complex genetic architecture of Ɗ13C. The five genomic regions with the largest effects were located on chromosomes 1, 2, 6, 7, and 9 and explained 55% of the phenotypic variation for Ɗ13C. Plant development stage had no effect on Ɗ13C expression, as phenotypic as well as genotypic correlations between Ɗ13C, flowering time, and plant height were not significant. To our knowledge, this is the first study demonstrating Ɗ13C to be under polygenic control in the C4 species maize.