外源SA对盐胁迫下颠茄生理生化、氮代谢及次生代谢的影响

采用无土栽培的方式,研究0.75mmol/L水杨酸(SA)对100mmol/L NaCl胁迫下颠茄幼苗生理生化、氮代谢与次生代谢的影响。结果表明,外源SA处理后:颠茄叶片叶绿素含量增多,最大光化学效率(Fv/Fm)、PSⅡ的潜在活性(F_v/F_o)、PSⅡ激发能捕获效率(F_v′/F_m′)、表观光合电子传递速率(ETR)、PSⅡ实际光化学效率(ΦPSⅡ)、光化学猝灭系数(qP)显著升高,初始荧光(Fo)、非光化学猝灭系数(qN)明显降低;超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性明显增强,丙二醛(MDA)含量明显降低;可溶性蛋白含量显著升高,脯氨酸和可溶性糖含量降低;NO3-含量增加,NH4+含量减少,谷氨酰胺合成酶(GS)和谷氨酸合成酶(GOGAT)活性提高,谷氨酸脱氢酶(GDH)活性降低;次生代谢产物莨菪碱和东莨菪碱含量显著提升。说明0.75mmol/L外源SA能显著改善100mmol/L NaCl胁迫下颠茄幼苗的光合性能,调节有机渗透物质含量,提高抗氧化酶活性,减小膜脂过氧化程度,以缓解盐胁迫造成的伤害。并使氮代谢相关酶活性恢复或增强,为生物碱的合成提供更多的前体物质和能量,从而直接或间接地促进了次生代谢产物的合成与积累。

Effect of exogenous SA on the physiological biochemistry,nitrogen metabolism and secondary metabolism of Atropa belladonna under NaCl stress

This study investigated the effect of exogenous salicylic acid (SA) on the physiology,biochemistry,nitrogen metabolism and secondary metabolism of Atropa belladonna seedlings under NaCl stress.We cultivated A.belladonna seedlings using soilless culture,treated with 100 mmol/L NaCl;0.75 mmol/L SA was also sprayed onto the surface of the leaves.After application of SA,chlorophyll content increased and maximal photochemical efficiency (Fv/Fm),potential activity of PSⅡ (Fv/Fo),the efficiency of excitation energy capture by open PS Ⅱ centers (Fv'/Fm'),photosynthetic electron transport rate (ETR),actual PS Ⅱ photochemical efficiency (ΦPS Ⅱ) and photochemical quenching coefficient (qP) were all greatly enhanced,while initial fluores cence (Fo) and non-photochemical quenching coefficient (qN) significantly decreased.The activities of superoxide dismutase (SOD),catalase (CAT) and peroxidase (POD) dramatically increased,while malondialdehyde (MDA) content decreased dramatically.Soluble protein content notably increased,while the contents of proline and soluble sugar decreased.The NO3-content increased,while the NH4 + content decreased.The activities of glutamine synthetase (GS) and glutamate synthetase (GOGAT) increased,while glutamate dehydrogenase (GDH) activity decreased.The secondary metabolites,scopolamine and hyoscyamine,were increased significantly.The study indicated that exogenous SA could enhance photosynthesis in A.belladonna,adjust organic osmotic content,increase antioxidant enzyme activities and reduce the degree of membrane lipid peroxidation,alleviating the damage of NaCl stress.The recovery or enhancement of the enzyme activities of nitrogen metabolism promoted the synthesis and accumulation of secondary metabolites directly or indirectly by providing more precursors and energy for the synthesis of tropane alkaloids.