Genome-Wide Association Study of Chlorophyll a, Chlorophyll b, Chlorophyll a/b Ratio and Total Chlorophyll Traits in Soybean Using Leaf Extracts.

Chlorophyll is a major component of chloroplasts and a better understanding of the genetic basis of chlorophyll content and concentration in soybean [Glycine max (L.) Merr.] might contribute to improving photosynthetic capacity and yield in regions with adverse environmental conditions. A collection of 332 diverse soybean genotypes were grown in two years (2009 and 2010) and chlorophyll a (chl a), chlorophyll b (chl b), and total chlorophyll (chl t) content as well as chlorophyll a/b ratio (chl a/b) in leaf tissues were determined. A genome-wide associating mapping approach was employed using 31,253 single nucleotide polymorphisms (SNPs) to identify loci associated with the extract based chl a, chl b, chl_a/b and chl_t measurements. These analyses revealed a tractable number of SNP markers significantly associated for the chlorophyll traits. A total of 23 (14 loci), 15 (7 loci), 14 (10 loci) and 26 SNPs (14 loci) showed significant association with chl a, chl b, chl a/b and chl t respectively. While many of the putative loci identified were located near genes previously identified or annotated as related to chlorophyll traits, numerous SNPs marked chromosomal regions where no known chlorophyll-related genes were found.