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

In plants with C 4 photosynthesis, physiological mechanisms underlying variation in stable carbon isotope discrimination (Δ 13 C) are largely unknown and genetic components influencing Δ 13 C have not been described. We analyzed a maize ( Zea mays ) introgression library (IL) derived from two elite parents to investigate whether Δ 13 C is under genetic control in this C 4 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 Δ 13 C as well as plant developmental and photosynthesis related traits. Highly heritable significant genetic variation for Δ 13 C was detected under field and greenhouse conditions. For several IL lines Δ 13 C values consistently differed from the recurrent parent within and across the two phenotyping platforms. Δ 13 C was significantly associated with 22 out of 164 analyzed genomic regions indicating a complex genetic architecture of Δ 13 C. 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 Δ 13 C. Plant development stage had no effect on Δ 13 C expression as phenotypic as well as genotypic correlations between Δ 13 C, flowering time and plant height were not significant. To our knowledge, this is the first study demonstrating Δ 13 C to be under polygenic control in the C 4 species maize.