Photosynthesis and heat tolerance of soybean
[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The Photochemical Reflectance Index (PRI) is determined from canopy spectral reflectance measurements and can provide important information about photosynthesis. The PRI can be used to assess the epoxidation state of xanthophyll pigments which provides information on non-photochemical quenching (NPQ) and the amount of energy used for photosynthesis. Genome wide association analyses were conducted to identify Single Nucleotide Polymorphisms (SNPs) and genomic loci associated with PRI using data from a soybean [Glycine max (L.) Merr.] diversity panel grown under field conditions in two years. Based on a mixed linear model, 31 unique candidate SNPs that identify 15 putative loci on 11 chromosomes were identified. Several candidate genes known to be associated with NPQ, photosynthesis, and sugar transport processes were identified in the proximity of 10 putative loci. Violaxanthin de-epoxidase, one of the identified genes, is directly involved in the xanthophyll cycle which plays a major role in NPQ. This study is the first to identify genomic loci for PRI and illustrates the potential of canopy spectral reflectance measurements for high-throughput phenotyping of a photosynthesis related trait. Significant SNPs, candidate genes, and genotypes contrasting for PRI identified in this study may prove useful for crop improvement efforts.
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