Effect of Drought Stress on Photosynthate Allocation and Remobilization in Common Bean Pods

Common bean is the most important staple grain legume for direct human consumption because of its high nutritional value. To maximize its nutritional potential, scientists aimed to improve its resistance to various stresses. Previous studies showed that photosynthate remobilization and partitioning is one of the major mechanisms of drought tolerance and overall productivity in common bean. Thus, scientists from the University of California, Davis aimed to determine the inheritance of pod harvest index (PHI) a measure of the partitioning of pod biomass to seed biomass, relative to that of grain yield. Their findings are reported in BMC Plant Biology.

The researchers assessed a recombinant inbred population of the cross of ICA Bunsi and SXB405, to know the impact of intermittent and terminal drought stresses on the genetic architecture of photosynthate allocation and remobilization in pods of common bean. The population was grown for two seasons, under well-watered conditions and terminal and intermittent drought stress in one year, and well-watered conditions and terminal drought stress in the second year.

Results showed that there was a significant effect of the water regime and year on all the traits, at both the phenotypic and quantitative trait locus (QTL). They identified 9 QTLs for pod harvest index, 8 QTLs for yield, 3 of which clustered with PHI QTLs, confirming the importance of photosynthate remobilization in productivity. Substantial epistasis was also found, explaining a considerable part of the variation for yield and PHI.  The findings show the genetic linkage of PHI and yield and confirm the role of PHI in the selection of both additive and epistatic effects controlling drought tolerance.

Read more findings in BMC Plant Biology.