Study On The Physiological Function Of Trehalose And Abscisic Acid Induced By Drought In The Process Of Carbohydrate Metabolism In Apple

The main apple production area in China is in the arid and semi-arid climate area,the Loess Plateau.Water deficit has became the main limiting factor for the development of apple.It is meaningful that explore the reason of fruit quality improvement under moderate drought condition.Potted seven or eight year-old dwarf apple(Malus domestica Borkh.cv.Gala)/M26(Malus pumila Mill.)trees were tested under 4 different treatment groups.Treatment 1: CK1,(75%-80% of the maximum amount of water in the field);LD1,50 days after anthesis light drought treatment(60%-65% of the maximum amount of water in the field);MD1,50 days after anthesis moderate drought treatment(50%-55%).Treatment 2: CK2,(75%-80% of the maximum amount of water in the field);LD2,100 days after anthesis light drought treatment(60%-65%);MD2,100 days after anthesis moderate drought treatment(50%-55%).Treatment 3: CK3,(distilled water);ABA,1mM exogenous ABA(75%-80% of the maximum amount of water in the field).Treatment 4: CK4,(distilled water);Tre,100 mM exogenous trehalose(75%-80% of the maximum amount of water in the field);LD+Tre,100 mM exogenous trehalose(60%-65% of the maximum amount of water in the field).High performance liquid chromatography(HPLC)and enzyme assay were used to determine the sugar concentration and activity of related enzymes in fruits.The main results are as follows:1、Through the determination of the basic quality of the fruit,the duration and intensity of drought significantly affected the weight of per fruit,but had no effect on the fruit shape index;The color a* value of fruit was significantly reduced by drought,indicating that drought affected the color of fruit;The hardness of fruit was significantly increased by drought,indicating that drought delayed the fruit ripening;The longer the drought,the smaller the relative water content of the fruit,and it is no significantly effect 100 days after anthesis drought;The solid acid ratio was highest in the light drought treatment,and the lowest in the control treatment.2、Under drought condition,the sucrose metabolism related enzymes: the activity of AI and NI was significantly rise,the activity of SS and SPS was significantly reduced,led to the decrease of the sucrose,and the increase of fructose and glucose;the sorbitol metabolism related enzymes: the activity of SDH and SOX was significantly decrease under drought condition,and the content of sorbitol was increased.The enzymes of trehalose metabolism:TPS and TPP was increased during the drought stress,and the activity of trehalase was decreased significantly,and led to an accumulation of trehalose.The changes of carbohydrate metabolism under drought condition may be related to the increase of ABA and endogenous trehalose content in the drought.3、After adding ABA,the content of endogenous ABA was increased,indicating that exogenous ABA treatment can be used to explore the role of ABA in the growth and development of fruit.The sucrose metabolic enaymes: the activity of AI、NI、SS and SPS was increased significantly,resulting in lower sucrose content and higher glucose and fructose content;The sorbitol metabolism relative enzyme: the activity of SDH and SOX was significantly decreased,so the content of sorbitol was increased.The activity of TPS and TPP was significantly increased,the trehalase was decreased,which was beneficial to the generation and accumulation of trehalose.It indicated that ABA could regulate fruit carbohydrate metabolism.4、Exogenous trehalose could increased the endogenous ABA,it is showed that exogenous trehalose could provide an approximate drought condition for plants.The acticity of AI、SS and SPS was increased significantly,and the activity of NI was reduced,it brings that reduced sucrose content and increased glucose and fructose content.The activity of SOX was increased while the activity of SDH was decreased,the content of sorbitol remained significantly increased.The activity of TPS and TPP was increased,and the due to exogenous trehalose increased the trehalose content,and the acticity of trehalase also increased.Exogenous trehalose with drought treatment,only decreased the activity of SDH,indecated that trehalose was involved in the regulation of glucose mebabolism,and maintain normal growth and development of plant under drought condition,relieve the impact of the drought on plants.