Improving Photosynthetic Capacity, Alleviating Photosynthetic Inhibition and Oxidative Stress Under Low Temperature Stress With Exogenous Hydrogen Sulfide in Blueberry Seedlings

In this study, we investigated the mechanism of photosynthesis and physiological function of blueberry leaves under low temperature stress (4–6°C) by exogenous hydrogen sulfide (H(2)S) by spraying leaves with 0.5 mmol·L(–1) NaHS (H(2)S donor) and 200 μmol·L(–1) hypotaurine (Hypotaurine, H(2)S scavenger). The results showed that chlorophyll and carotenoid content in blueberry leaves decreased under low temperature stress, and the photochemical activities of photosystem II (PSII) and photosystem I (PSI) were also inhibited. Low temperature stress can reduce photosynthetic carbon assimilation capacity by inhibiting stomatal conductance (G(s)) of blueberry leaves, and non-stomatal factors also play a limiting role at the 5(th) day of low temperature stress. Low temperature stress leads to the accumulation of Pro and H(2)O(2) in blueberry leaves and increases membrane peroxidation. Spraying leaves with NaHS, a donor of exogenous H(2)S, could alleviate the degradation of chlorophyll and carotenoids in blueberry leaves caused by low temperature and reduce the photoinhibition of PSII and PSI. The main reason for the enhancement of photochemical activity of PSII was that exogenous H(2)S promoted the electron transfer from Q(A) to Q(B) on PSII acceptor side under low temperature stress. In addition, it promoted the accumulation of osmotic regulator proline under low temperature stress and significantly alleviated membrane peroxidation. H(2)S scavengers (Hypotaurine) aggravated photoinhibition and the degree of oxidative damage under low temperature stress. Improving photosynthetic capacity as well as alleviating photosynthetic inhibition and oxidative stress with exogenous H(2)S is possible in blueberry seedlings under low temperature stress.