Analysis of salt stress induced changes in Photosystem II heterogeneity by prompt fluorescence and delayed fluorescence in wheat ( Triticum aestivum) leaves

► Effect of high salt stress on changes in antenna and reducing side heterogeneity of PSII is reported. ► PFIC and DFIC techniques were found to be compatible with each other. ► Both the techniques can be used together to confirm the status of PSII under any stress condition. In order to investigate changes in the heterogeneity of PSII, prompt fluorescence induction curves (PFIC) and delayed fluorescence induction curves (DFIC) were measured in wheat leaves after salt treatment. From these data, antenna heterogeneity and reducing side heterogeneity were estimated. Results show that antenna size, which is further differentiated into α, β and γ PSII centers, is changed under salt stress conditions. At higher salt concentration, there is a decrease in the number of α PSII centers with simultaneous increase in the amount of β and γ PSII centers. Another aspect of antenna heterogeneity is explained in terms of connectivity (or grouping) between PSII centers which did not change significantly under salt stress. Reducing side heterogeneity was assessed by both DFIC and PFIC and results show that a significant increase in the conversion of Q B-reducing centers to Q B-non-reducing centers is observed under salt stress.