Slow darkening of pinto bean seed coat is associated with significant metabolite and transcript differences related to proanthocyanidin biosynthesis
Duwadi, K., Austin, R.S., Mainali, H.R., Bett, K., Marsolais, F., Dhaubhadel, S. (2018). Slow darkening of pinto bean seed coat is associated with significant metabolite and transcript differences related to proanthocyanidin biosynthesis. BMC Genomics, [online] 19(1), http://dx.doi.org/10.1186/s12864-018-4550-z
Plain language summary
Postharvest darkening of seed coat in pinto bean (Phaseolus vulgaris L.) is an undesirable trait that affects its market value. Darkening is more rapid in the adapted cultivars like CDC-Pintium than the newly developed slow darkening cultivar 1533-15. In this research we compared the gene expression profiles of CDC-Pintium and 1533-15 and identified the key genes that may play a role in seed coat darkening trait in pinto beans.
Background: Postharvest seed coat darkening in pinto bean is an undesirable trait resulting in a loss in the economic value of the crop. The extent of darkening varies between the bean cultivars and their storage conditions. Results: Metabolite analysis revealed that the majority of flavonoids including proanthocyanidin monomer catechin accumulated at higher level in a regular darkening (RD) pinto line CDC Pintium than in a slow darkening (SD) line 1533-15. A transcriptome analysis was conducted to compare gene expression between CDC Pintium and 1533-15 and identify the gene (s) that may play a role in slow darkening processes in 1533-15 pinto. RNAseq against total RNA from RD and SD cultivars found several phenylpropanoid genes, metabolite transporter genes and genes involved in gene regulation or modification to be differentially expressed between CDC Pintium and 1533-15. Conclusion: RNAseq analysis and metabolite data of seed coat tissue from CDC Pintium and 1533-15 revealed that the whole proanthocyanidin biosynthetic pathway was downregulated in 1533-15. Additionally, genes that encode for putative transporter proteins were also downregulated in 1533-15 suggesting both synthesis and accumulation of proanthocyanidin is reduced in SD pintos.