Description:
<p>In plants with C₄ photosynthesis, physiological mechanisms underlying variation in stable carbon isotope discrimination (Δ¹³C) are largely unknown, and genetic components influencing Δ¹³C have not been described. We analyzed a maize (Zea mays) introgression library derived from two elite parents to investigate whether Δ¹³C 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 Δ¹³C as well as plant developmental and photosynthesis-related traits. Highly heritable significant genetic variation for Δ¹³C was detected under field and greenhouse conditions. For several introgression library lines, Δ¹³C values consistently differed from the recurrent parent within and across the two phenotyping platforms. Δ¹³C was significantly associated with 22 out of 164 analyzed genomic regions, indicating a complex genetic architecture of Δ¹³C. 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 Δ¹³C. Plant development stage had no effect on Δ¹³C expression, as phenotypic as well as genotypic correlations between Δ¹³C, flowering time, and plant height were not significant. To our knowledge, this is the first study demonstrating Δ¹³C to be under polygenic control in the C₄ species maize.</p>