Effect of exogenous carbon monoxide donor Hematin on photosynthesis parameters and chlorophyll fluorescence characteristics of Coptis chinensis seedlings under NaCl stress / 中草药

ABSTRACT

Objective: Using exogenous carbon monoxide (CO) donor Hematin (H) to study the changes of photosynthesis parameters and chlorophyll fluorescence characteristics in Coptis chinensis seedlings under NaCl stress and get the way for promoting the resistance ability of C. chinensis seedlings under NaCl stress. Methods: Under 100 mmol/L NaCl stress, the several physiological indexes of C. chinensis seedlings treated by H at the different concentration, such as the contents of photosynthetic pigment and the parameters of chlorophyll fluorescence and photosynthesis, were measured. Results: Under NaCl stress the photosynthetic physiology of C. chinensis seedlings was inhibited, but the contents of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids could be obviously increased after the treatment of H at different concentration. The levels of the net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) in C. chinensis seedlings were all decreased, which would gradually increase with the time and concentration increase of NaCl stress, while the concentration of CO2 (Ci) increased with the opposite tendency. These results indicated that the main influencing factor of decreasing Pn of C. chinensis was non-stomatal factors. After being treated with different exogenous substances, the Pn, Gs, and Tr were all increased in different degrees, but the level of Ci was decreased. And the maximum fluorescence (Fm), photochemical efficiency of photosystem II (Fv/Fm), potential photochemical efficiency (Fv/Fo), photochemical efficiency (Fv'/Fm'), PSII actual photochemical efficiency (ΦPSII), photochemical quenching coefficient (qP), electronic transfer rate (ETR), and photochemistry rate (PCR) were obviously increased, while the levels of minimal fluorescence (Fo), non-photochemical quenching coefficient (NPQ), and heat dissipation rate (HDR) were effectively decreased. Conclusion: Exogenous CO H with the appropriate concentration of 2.0 mmol/L could reduce the excess excitation dissipation, improve photochemical electron transport efficiency, and efficiently protect C. chinensis leaves from PSII damage by significantly alleviating the damages of salt stress to C. chinensis so that H could obviously promote the salt resistance to C. chinensis under salt stress.