甘露糖对白三叶抗旱性、糖及糖醇类代谢物积累的影响

Effects of exogenous mannose application on drought tolerance, sugars, and sugar alcohol accumulation in white clover

以广泛栽培种植的‘Ladino’白三叶为供试材料,采用生理生化及气相色谱-质谱联用(GC-MS)技术,从叶片水分状况、渗透调节、抗氧化性、光合特征、糖及糖醇类物质的积累研究甘露糖对白三叶抗旱性的影响。研究结果表明,干旱胁迫显著降低白三叶叶片相对含水量、叶绿素含量、叶绿素荧光和净光合速率,导致膜脂过氧化加剧,细胞膜稳定性降低,植株受损严重。但白三叶能通过提高自身水分利用效率及降低渗透势以适应干旱胁迫。外施适宜浓度的甘露糖(30 mmol·L^-1)能显著提高干旱胁迫下白三叶叶片光合作用、抗氧化和渗透调节能力,从而有效缓解干旱诱导的氧化伤害并维持良好的水分状况,提高植株抗旱性。通过对不同糖及糖醇类代谢物含量变化的测定发现,不同糖类积累对干旱胁迫响应有所不同,甘露糖能在干旱条件下诱导多种糖(甘露糖、葡萄糖、果糖、半乳糖、木糖、蔗糖、麦芽糖和海藻糖)和糖醇(肌醇、丙三醇和松醇)的积累,这既提高了干旱胁迫下细胞渗透调节能力,也为白三叶生长和代谢供能提供更多的可利用碳水化合物以抵御干旱胁迫。

Effects of exogenous application of mannose on water status,osmotic adjustment,antioxidant capacity,photosynthetic response,sugars,and sugar alcohol accumulation in‘Ladino’white clover were studied under drought stress using physiological analysis and gas chromatography-mass spectrometer(GC-MS)technology.Results showed that drought stress significantly decreased relative water content,chlorophyll content,photochemical efficiency(F v/F m),and net photosynthesis rate resulting in membrane lipid peroxidation and decrease in cell membrane stability in leaves of white clover.However,white clover improved water use efficiency and decreased osmotic potential in order to acclimate to drought stress.The application of exogenous mannose(30 mmol·L^-1)significantly increased photosynthesis,total antioxidant capacity,and osmotic adjustment,thereby alleviating drought-induced oxidative damage and maintaining better water balance during drought stress.GC-MS analysis showed that drought stress induced differential changes of many sugars and sugar alcohols in leaves of white clover.Exogenous mannose application enhanced the accumulation of many sugars(mannose,glucose,fructose,galactose,xylose,sucrose,maltose,and trehalose)and sugar alcohols(myo-inositol,glycerol,and D-pinitol)in white clover under drought stress contributing to improved osmotic adjustment and energy supply for the maintenance of growth.