Pan Dong-Yun, Fu Xin, Zhang Xiao-Wei, Liu Feng-Jiao, Bi Huan-Gai, Ai Xi-Zhen
College of Horticulture Science and Engineering, Shandong Agricultural University/State Key Laboratory of Crop Biology/Key Laboratory of Horticultural Crop Biology and Germplasm Innovation in Huanghuai Region, Ministry of Agriculture/Shandong Collaborative Innovation Center of Fruit & Vegetable Qua-lity and Efficient Production, Tai'an 271018, Shandong, China.
Ying Yong Sheng Tai Xue Bao. 2020 Sep 15;31(9):3023-3032. doi: 10.13287/j.1001-9332.202009.028.
Both salicylic acid (SA) and hydrogen sulfide (HS) play an important role in regulating plant growth and development and physiological metabolism under abiotic stresses. As signal molecules, the interaction between them in regulating cucumber photosynthesis under low temperature and low light is still unclear. Here, we examined the regulation and interaction of SA and HS on photosynthesis in cucumber seedlings under low temperature (8 ℃/5 ℃, day/night) and low light (100 μmol·m·s). Seedlings were foliar-sprayed with SA, sodium sulfide (NaHS, HS donor), and their scavenger or biosynthesis inhibitors, respectively. Seedlings treated with deionized water at suitable temperature and light condition were used as the control. The results showed that SA increased the L-/D-cysteine desulfhydrase (LCD, DCD) activities and relative mRNA expression, and consequently promoted the endogenous HS production. However, NaHS did not affect the activities and gene expressions of phenylalnine ammonialyase and isochorismate and endogenous SA level. Compared with the HO-treated seedlings under low temperature and low light, SA- and NaHS-treated seedlings showed an increase in the photosynthetic rate, stomatal conductance and transpiration rate, while a decrease in intercellular CO concentration. SA and NaHS increased the CO assimilation, which mainly attributed to the increases in the activities of the ribulose-1, 5-bisphosphate carboxylase, rubisco activase, sedoheptulose-1, 7-bisphosphatase and fructose-1, 6-bisphosphatase, as well as their mRNA expression. Meanwhile, SA and NaHS improved the actual photochemical efficiency and maximal photochemical efficiency of PSII, and therefore alleviated the damage in photosynthetic apparatus and negative effect on growth from low temperature and low light stress. The SA-induced higher photosynthesis and growth in stressed seedlings were suppressed by addition of HS scavenger hypotaurine. However, the HS-induced tolerance of photosynthetic apparatus to low temperature and low light was not affected by SA biosynthesis inhibitor paclobutrazol and 2-aminoindan-2-phosphonic acid. Our results suggested that HS, as a downstream signal of SA, was involved in regulating photosynthesis in cucumber seedlings under low temperature and low light.
水杨酸（SA）和硫化氢（HS）在非生物胁迫下调节植物生长发育和生理代谢过程中均发挥着重要作用。作为信号分子，它们在低温弱光条件下对黄瓜光合作用的调控及相互作用尚不清楚。在此，我们研究了SA和HS对低温（8℃/5℃，昼/夜）弱光（100μmol·m·s）条件下黄瓜幼苗光合作用的调控及相互作用。分别对幼苗进行SA、硫化钠（NaHS，HS供体）及其清除剂或生物合成抑制剂的叶面喷施处理。在适宜温度和光照条件下用去离子水喷施处理的幼苗作为对照。结果表明，SA提高了L-/D-半胱氨酸脱巯基酶（LCD，DCD）活性及相对mRNA表达，从而促进了内源HS的产生。然而，NaHS对苯丙氨酸解氨酶、异分支酸合成酶的活性及基因表达以及内源SA水平并无影响。与低温弱光下喷施HO的幼苗相比，喷施SA和NaHS的幼苗光合速率、气孔导度和蒸腾速率增加，而胞间CO浓度降低。SA和NaHS提高了CO同化作用，这主要归因于1,5-二磷酸核酮糖羧化酶、rubisco活化酶、景天庚酮糖-1,7-二磷酸酶和果糖-1,6-二磷酸酶活性及其mRNA表达的增加。同时，SA和NaHS提高了PSII的实际光化学效率和最大光化学效率，因此减轻了光合机构的损伤以及低温弱光胁迫对生长的负面影响。添加HS清除剂次牛磺酸可抑制SA诱导的胁迫幼苗较高的光合作用和生长。然而，SA生物合成抑制剂多效唑和2-氨基茚-2-膦酸并不影响HS诱导的光合机构对低温弱光的耐受性。我们的结果表明，HS作为SA的下游信号，参与调控低温弱光条件下黄瓜幼苗的光合作用。
