James Santiago (Sharkey lab)
Date & Location: April 14, 2020, at 12p; Room 168 Plant Biology Building
Subject: Role of source leaf sucrose export in anther G6PDH activity in two bean varieties differing in thermotolerance capacity
Abstract: Common bean (Phaseolus vulgaris) is an economically important crop in Michigan but it is sensitive to elevated temperatures. Rising global temperatures threaten dry bean production in the US. Bean plants at the reproductive stage are more susceptible to heat stress due to damage to male (anthers) and female (ovary) reproductive tissues, with anthers being the most susceptible to heat. Damage includes early tapetal cell degradation, anther indehiscence, pollen deformation, and loss of pollen viability. In beans, early tapetum cell degradation caused by elevated temperature has been shown to cause male sterility. In male sterile plants, tapetum degradation is caused by accumulation of reactive oxygen species (ROS).
In the present study, we focus on understanding how anther G6PDH activity contribute to male reproductive tolerance in common beans. We hypothesize that anther G6PDH is involved in producing reductants that is used by antioxidant enzymes to quench ROS at elevated temperature. We further hypothesize different G6PDH activities between heat-tolerant and sensitive bean genotypes after heat treatment. To test our hypothesis, we analyzed heat-tolerant and susceptible common bean genotypes using a combination of phenotypic, biochemical, and physiological approaches. The results of these analyses identified dissimilarities in leaf sucrose export, anther sugar accumulation, and anther pentose phosphate metabolism between genotypes. We also found differences in antioxidant enzyme activities between bean cultivars and found evidence that G6PDH plays a role in supporting NADPH-dependent ROS quenching. Overall, our study highlights the importance of maintaining carbon flux and anther carbon metabolism at high temperature to contribute in conferring heat tolerance in common beans.
Speaker Lab: Dr. Thomas Sharkey