Abstract

Leaf photosynthesis and biological nitrogen fixation are two of the most important metabolic processes for soybean growth and development. Since they are considered closely linked, measuring chlorophyll content using non-destructive tools, such as a Soil Plant Analysis Development (SPAD) chlorophyll meter, may help determine the nodulation and nitrogen fixation status of soybean plants. This study aimed to identify single nucleotide polymorphism (SNP) markers associated with SPAD values in a global panel of 187 diverse accessions. The population structure and genome-wide association analyses were carried out using 1,243 high-quality SNPs and greenhouse data obtained in two consecutive years. The results revealed 14 SNPs significantly related to SPAD values on Chr. 5, 10, 12, 15, 17, and 18. In addition, 33 candidate genes were found in the Glyma.Wm82.a2 within 10 kb flanking regions of each significant SNP. Of these, three candidate genes on Chr. 10 and 12 encoded proteins related to photosynthesis, chlorophyll content, and nitrogen status. Overall, our data may help better understand the underlying molecular mechanisms controlling chlorophyll content in relation to nitrogen fixation in soybean.