PhD position on the function of flavonols in promoting reproductive thermotolerance in plants

This project will examine the role of flavonols – plant specialized metabolites with potent in vitro antioxidant properties – in promoting pollen development and seed set during heat stress. Production of seed and fruit crops depends on successful sexual reproduction. Plant sexual reproduction involves development of pollen grains and delivery of sperm cells within the pollen grains to the female gametophyte through the growth of a pollen tube. Pollen development and tube growth are highly sensitive to heat stress. Increases in temperatures linked to climate change will thus undermine crop yields.

A hallmark of heat stress is increased generation of reactive oxygen species (ROS). Overaccumulation of ROS leads to oxidative stress, which impairs normal plant growth and development. However, localized production of basal ROS levels drives signaling pathways involved in normal plant developmental and physiological processes. To maintain ROS at levels conducive to signaling, plants use diverse enzymatic and non-enzymatic antioxidant machineries. Flavonols are a class of plant specialized metabolites with potent ROS scavenging activity. We previously reported that flavonols prevent ROS from reaching inhibitory levels at normal and increased temperatures, thereby promoting pollen viability and tube growth.

It is however largely unknown where and when ROS and flavonols are synthesized in developing pollen and surrounding tissues, if ROS and flavonol biosynthesis is regulated by heat stress in these tissues and if flavonols act as ROS scavengers during pollen development. You will study ROS and flavonol accumulation and biosynthetic pathways in response to heat stress in developing anthers and pollen grains. Using genetic and pharmacological approaches to manipulate the ROS and flavonol biosynthetic pathways, you will test how these compounds regulate pollen development in normal and heat stress conditions and if flavonols act as ROS scavengers in developing anthers and pollen grains. This project will be performed using the agriculturally important crop Solanum lycopersicum (tomato), for which molecular and genomic resources are well developed.