Identifying stress tolerance genes in plants from distantly related crop relatives
Heat stress leads to male germ line (pollen) sterility, and consequently, failure to produce seeds and fruits, yet little is known about why developing pollen is so vulnerable at the molecular level. My PhD aims to identify molecular mechanisms behind the heat sensitivity of male cell lines. I have exposed different stages of pollen development, both in commercial and an Australian wild Gossypium, to moderate and extreme heat to investigate the molecular response to heat. Using physiological experiments and -omics approaches, I have found that tetrad formation (circa meiosis) in commercial cotton is the most vulnerable stage of pollen development to heat. The sensitivity of tetrads in the commercial cotton is most likely due to impaired mRNA splicing machinery, translation of non-essential genes and enhanced level of protein transport, compared with the later stages of development and vegetative tissues. Importantly, the findings in the wild cotton demonstrated different molecular responses of pollen to high temperature, which might contribute to its thermotolerance. The identified genes and pathways from the wild cotton pollen allows us to speculate on mechanisms of thermotolerance in male reproductive cell lines. These findings provide insights for future studies that will eventually lead to development of new cultivars for hotter environments.