Physiological and Lipidomic Characterization of Heat Response in Peanut

Peanut (Arachis hypogea L.) is an important crop grown worldwide for its nutritional value and economic significance. Reducing the costs of production and improving profitability are major goals of the peanut industry. However, increasing global temperatures present a serious challenge to achieving these goals. Peanut plants are highly sensitive to heat stress during flowering stage due to poor pollen performance that results in reduced fruit-set and yield. The objective of this study was to evaluate the anther lipidome of peanut cultivars to identify specific lipid traits or species that are associated with better pollen performance under heat stress. Six peanut cultivars with varying degrees of drought and/or heat tolerance were evaluated in a field study under open field (control) and heat stress (HT) conditions in Summer 2018. Heat tents were used to impose heat stress when the last cultivar reached anthesis. Stress treatment lasted for 17 days. Peanut anthers were collected on the 13th day of stress. Anther lipid profiling was done using electrospray ionization-triple quadrupole mass spectrometry (ESI-MS/MS). Chlorophyll fluorescence, chlorophyll index, and pollen viability were also measured during the stress period. After the stress period ended, all plants were kept under open field conditions until final harvest at maturity. Preliminary results showed that significant effect of treatment and/or cultivar were found on chlorophyll index and maximum quantum yield of PSII. Based on these traits, Tifguard was the most stress-tolerant and Bailey was the most stress-susceptible cultivar. Heat stress decreased the unsaturation levels of polar lipids. Generally, Tifguard maintained a lower and Bailey a higher level of polar lipid unsaturation. Within the framework of the current knowledge on lipid metabolism, these results suggest that lowering the lipid unsaturation levels under HT conditions is a mechanism associated with the contrasting responses to HT of these cultivars