Chlorophyll fluorescence, leaf gas exchange, and genomic analysis of chromosome segment substitution rice lines exposed to drought stress

Abstract

This research aims to evaluate the photosynthesis-related parameters in rice chromosome segment substitution lines (CSSL), containing drought-tolerant region from DH212 in a Khao Dawk Mali105 genetic background. Screening at seedling stage indicated that CSSL4 was more tolerant to drought stress than KDML105 with the higher maximal quantum yield of PSII photochemistry. After withholding water, the decline in light-saturated net photosynthetic rate due to drought stress occurred simultaneously with the decrease in electron transport rate and effective quantum yield of PSII photochemistry values, suggesting that stomatal changes affect light-saturated net photosynthetic rate (PNmax) during the initial drought response. KDML105 rice showed the highest level of electron transport rate/PNmax ratio. This suggested that KDML105 has the lowest ability to use reducing power in photosynthesis process under drought stress conditions. Loci containing single nucleotide polymorphisms between CSSL4 and KDML105 were subjected for co-expression network analysis with 0.99 correlation. The co-expression between calmodulin-stimulated calcium-ATPase and C2H2 zinc finger protein was detected. This locus may contribute to the maintenance ability of photosynthesis process under drought stress conditions.