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.

[bmcplantbiol.biomedcentral.com]