Identification and functional analysis of GmPsaL regulating pod color in vegetable soybean

Vegetable soybean is rich in nutrients and has a unique flavor. It is highly preferred by people because of its pharmacological activities, including those that regulate the intestines and lower blood pressure. The pod color of vegetable soybeans is an important quality that indicates their freshness and has a significant impact on their commercialization.

In this study, pod color was evaluated in 301 vegetable soybean accessions collected from various regions. Genome-wide association analysis was carried out using the Mixed linear model (MLM), a total of 18 quantitative trait loci including 117 SNPs were detected. Two significant QTLs located on chromosomes 6 (qGPCL4 /qGPCa1/qGPCb2) and 18 (qGPCL10/qGPCb3) were consistently detected across different variables. Based on gene functional annotation, 30 candidate genes were identified in these two candidate intervals. Combined with transcriptome analysis, Glyma.18g241700 has been identified as a candidate gene for regulating pod color in vegetable soybeans. Glyma.18g241700 encodes a chlorophyll photosystem I subunit XI. which localizes to the chloroplast named GmPsaL, qRT-PCR analysis showed that GmPsaL was specifically highly expressed in developing pods. Furthermore, overexpression of GmPsaL in transgenetic Arabidopsis plants produced dark green pods.

These findings may be useful for clarifying the genetic basis of the pod color of vegetable soybeans. The identified candidate genes may be useful for the genetic improvement of the appearance quality of vegetable soybeans.