外源24-表油菜素内酯对亚低温弱光胁迫下番茄叶片碳同化和抗氧化代谢的影响

Effects of exogenous 24-epibrassinolide on carbon assimilation and antioxidant metabolism of tomato leaves under sub-low temperatures and weak light stress

以番茄品种‘合作903’为试材,采用基质栽培的方式,研究外源喷施24-表油菜素内酯(EBR)对亚低温弱光复合胁迫下番茄幼苗生长、碳同化和抗氧化代谢的影响。结果表明,亚低温弱光胁迫显著降低番茄幼苗株高和干鲜重,外源EBR缓解复合胁迫诱导的生长抑制。胁迫条件下施用EBR处理后,番茄叶片Rubisco最大羧化速率(V_(cmax))、最大电子传递速率(J_(max))、磷酸丙糖利用率(TPU)和羧化效率(CE)分别显著提高了113.57%、90.71%、38.92%和287.50%,CO_2补偿点(CCP)降低了16.38%。EBR显著增加了复合胁迫下番茄叶片蔗糖磷酸合成酶(SPS)和蔗糖合酶(SS)的活性,而降低酸性转化酶(AI)活性,导致可溶性糖含量、果糖含量和蔗糖含量下降。外源EBR显著提高了亚低温弱光胁迫下番茄叶片抗氧化酶的活性,与单纯复合胁迫相比,超氧化物岐化酶(SOD)、过氧化物酶(POD)、抗坏血酸氧化酶(APX)和过氧化氢酶(CAT)的活性分别增加了31.78%、65.69%、59.99%和187.66%,并降低了超氧阴离子(O_2^(ˉ·))产生速率和丙二醛(MDA)含量。说明EBR通过调节碳同化和抗氧化代谢,缓解了亚低温弱光复合胁迫对番茄生长的抑制,进而增强胁迫条件下番茄植株的抗性。

In the present study, the tomato ‘Hezuo903’ as test material with substrate culture, we investigated the effects of exogenous 24-epibrassinolide（EBR） on growth, carbon assimilation and antioxidant metabolism of tomato leaves under sub-low temperature and weak light stress conditions. The results showed that EBR significantly alleviated the inhibition of plant growth, and increased the fresh and dry weights of tomato seedlings under a combined low temperature and weak light stress. Under stress conditions, EBR significantly increased the maximum carboxylase activity of ribulose-1,5-bisphosphate（Vcmax）, the maximal velocity of Ru BP regeneration（Jmax）, triosephosphate utilization capacity（TPU） and carboxylation efficiency（CE） by 113.57%, 90.71%, 38.92% and 287.50%, respectively, but remarkably reduced CO2 compensation point（CCP） by 16.38%. Moreover, EBR significantly increased the activities of sucrose phosphate synthetase（SPS） and sucrose synthase（SS） and decreased the acid invertase（AI） activity in tomato leaves under a combined sub low temperature and weak light stress, and thus resulting in the notable decreases in total soluble sugar, fructose and sucrose contents. Furthermore, EBR increased the activities of superoxide dismutase（SOD）, peroxidase（POD）, ascorbate peroxidase（APX）, and catalase（CAT） by 31.78%, 65.69%, 59.99% and 187.66%, respectively, as compared with the combined stress conditions, and significantly decreased the production rate of superoxide anion（O2--·）） and malondialdehyde（MDA） content. These results suggest that EBR could regulate the carbon assimilation and antioxidant metabolism in tomato leaves, and therefore alleviated the inhibition of tomato growth and enhanced the resistance of tomato plants to a combined sub-low temperature and weak light stress.