Genetic dissection of high temperature stress tolerance using photosynthesis parameters in QTL introgressed lines of rice cv. Improved White Ponni

Abstract

Photosynthesis is fundamental to biomass production, but sensitive to high temperature stress. To understand the genetics of leaf photosynthesis, especially under heat, RILs of rice cv. Improved White Ponni (IWP) introgressed with QTLs controlling spikelet fertility (qHTSF 1.1 and qHTSF 4.1) were grown in temperature controlled chambers (TCCs). The temperature inside the TCCs were maintained at ambient and elevated temperatures. Gas exchange and chlorophyll fluorescence were measured to evaluate introgressed lines for high temperature stress tolerance. It was observed that, the lines introgressed with both the QTLs (# 246, # 295, # 296, # 277) had higher photosynthetic rate coupled with higher stomatal conductance and lower transpiration rate. These lines also exhibited higher PSII quantum yield. The lines with one positive QTL either qHTSF 1.1 or qHTSF 4.1 showed better gas exchange and PSII quantum yield as compared to negative lines under high temperature stress. This shows that the physiological basis of the introgressed QTLs controls the spikelet fertility by maintaining the photosynthetic rate and chlorophyll fluorescence and minimizing the transpiration rate under high temperature stress.