外源L-肌肽对鲜切苹果蔗糖代谢的影响OA

To improve the storage quality of fresh-cut apples,this research investigates the effects of various concentrations of L-carnosine on sucrose metabolism in fresh-cut apples.Using"Red Fuji"apples as experimental materials,fresh-cut apples are immersed in L-carnosine solutions(0.5,2.0,3.5,and 5.0 mmol L-1).The optimal concentration of 2 mmol L-1 is determined through analyzing the changes in respiratory rate and soluble solids content(SSC).Simultaneously,the impact of L-carnosine at optimal concentration on the contents of sucrose,fructose,and glucose are examined.The study further evaluates the influence of L-carnosine on the activities of sucrose phosphate synthase(SPS),sucrose synthase(synthetic direction:SS-s;degradative direction:SS-d),neutral invertase(NI)and acid invertase(AI),as well as changes in the expression levels of MdSS,MdSPS,and MdNI.The results demonstrate that 2 mmol L-1 L-carnosine significantly suppresses the increase in respiratory rate and maintains higher SSC levels.L-carnosine promotes the accumulation of sucrose and slows its degradation by increasing the activities of SPS and SS-s enzymes,inhibiting the activities of SS-d,NI,and AI enzymes,and upregulating the relative expression levels of the MdSS,MdSPS,and MdNI genes.Consequently,it suppresses the increase in glucose and fructose content and maintains better fruit storage quality.