草业学报2018，Vol.27Issue(5)：130-140,11.DOI:10.11686/cyxb2017235
NO介导的Ca2+信号对渗透胁迫下紫花苜蓿幼苗光合特征及抗性的影响
Role of NO-mediated Ca2+ signaling in regulation of photosynthesis and resistance to osmotic stress in alfalfa seedlings
摘要
Abstract
The nitric oxide (NO) and Ca2+ transduction pathways have been implicated in mediating stress response and tolerance in plants.However,little is known about the interaction between NO and Ca2+ signals,in regulation of photosynthesis and antioxidant capacity of alfalfa seedlings under drought stress.This research aimed to explore the mechanism by which Ca2+ signaling mediated by nitric oxide (NO) in Medicago sativa seedlings regulates photosynthesis and antioxidant enzyme activity under osmotic stress.Solutions with:(i) differing osmotic potentials obtained using poly ethylene-glycol-6000 (PEG);(ii) a nitric oxide donor sodium nitroprusside (SNP);(iii) an exogenous Ca2+ signaling donor,calcium chloride (CaCl2);(iv) an NO blocker (methylene blue,MB);and (v) a Ca2+ channel blocker (LaCl3),were pre-sprayed onto the leaves of alfalfa seedlings in different combinations.The effect of the NO-mediated Ca2+ signaling on the photosynthetic pigment content,gas exchange parameters,antioxidant enzyme activity,on the levels of malondialdehyde (MDA) and proline,and on the peroxidase (POD) isoenzyme electrophoresis atlas were studied in leaves of alfalfa under osmotic stress simulated by 15％ PEG.Results show that the photo-physiological characteristics of alfalfa seedling were significantly affected by osmotic stress.NO and Ca2+ application alleviated the decrease of chlorophyll a,carotenoid contents and the total chlorophyll contents,increased net photosynthetic rate (Pn),stomatal conductance (Gs) and stomatal limited value (Ls),but reduced intercellular CO2 concentration (Ci) in alfalfa seedling leaves.Furthermore,compared to SNP or CaCl2 treatment alone,SNP and CaCl2 treatments applied together significantly increased the activities of SOD,POD,CAT and the content of proline by 39.29％,30.41％,56.24％ and 45.59％,respectively,and decreased the content of MDA by 45.59％.The POD is ozymeprofile exhibited the greatest band number and strongest enzyme activity on the fourth day,and new band appeared after combined NO and Ca2+ treatment.Interestingly,when exogenous Ca2+ was added together with MB,the promotional activity of Ca2+ was inhibited.In addition,La3+ inhibited the promotional effect of NO.This indicated that in leaves of alfalfa seedlings under osmotic stress,Ca2+ mediated signaling transduction pathways,when induced by NO,helped to maintain antioxidant activity and prevent damage to photosynthesis systems.关键词
一氧化氮/钙离子/紫花苜蓿/渗透胁迫/光合特性/抗氧化酶Key words
nitric oxide/Ca2+/Medicago sativa/osmotic stress/photosynthesis/antioxidant enzymes引用本文复制引用
赵颖,弋钦,魏小红,辛夏青,韩厅,岳凯,王方琳..NO介导的Ca2+信号对渗透胁迫下紫花苜蓿幼苗光合特征及抗性的影响[J].草业学报,2018,27(5):130-140,11.基金项目
国家自然基金项目(31560663)和甘肃省自然基金项目(145RJZA196)资助. （31560663）
