| Gleditsia sinensis is a species of saponacia in the family of hematoxylaceae,which can withstand various drought conditions.It has been used in medicine,food,health care,cleaning supplies and landscaping.At present,the lack of water resources has become one of the most critical factors limiting the construction of global ecological environment.Drought is an abiotic adversity obstacle to the industrial development of Gleditsia sinensis in northern China,which limits the accumulation of chemical composition and biomass of Gleditsia sinensis.However,few reports focused on the mechanism of drought response regulation.In order to understand the metabolic basis of Gleditsia sinensis,this study systematically studied the effects of drought stress and rehydration on photosynthesis,antioxidant enzyme activity,primary metabolites and phenolic metabolites of Gleditsia sinensis leaves by applying different intensities of drought stress to Gleditsia sinensis seedlings and rehydrating the samples of Gleditsia sinensis leaves under severe drought stress The metabolic basis provides valuable information for the molecular mechanism of drought resistance of Gleditsia sinensis.The conclusion is as follows:(1)With the increase of drought stress intensity,the leaves of Gleditsia sinensis seedlings were damaged in different degrees,and the growth of Gleditsia sinensis seedlings was inhibited.The chlorophyll content and gas exchange parameters(Photo,Cond,Ci and Tr)of saponifia seedlings decreased,and photosynthesis recovered after rehydration.It indicated that drought stress reduced the actual photosynthetic capacity of saponifia seedlings,resulting in a serious reduction of biomass.(2)Under drought stress,the content of MDA and the activity of four antioxidant enzymes(SOD,POD,APX and CAT)in leaves of Gleditsia sinensis increased with the increase of stress intensity.After rehydration,the content of MDA in leaves decreased significantly,but it did not return to the control level,and the activity of antioxidant enzymes did not return to the control level.That is to say,the seedlings of Gleditsia sinensis have a certain degree of drought resistance,after rehydration,Gleditsia sinensis will have a certain compensation effect,but severe drought will cause irreversible damage to plant tissues.(3)The samples were analyzed by global metabonomics based on GC-MS platform.A total of 82 primary metabolites were identified,of which 17 key metabolites(7 sugars and 10 amino acids)showed significant increase or decrease under drought stress,and were considered as important metabolites(p<0.05 and VIP>1).A large number of amino acids and sugars are believed to participate in osmotic regulation,and partially compensate for the energy consumption under drought stress.The biosynthesis of resistance related amino acids and carbohydrate metabolites meets the high requirements of saponaria seedling growth and repair.(4)22 kinds of metabolites(p<0.05 and VIP>1)were identified by LC-MS,which were phenolic metabolites of C6C1,C6C3 and C6C3C6 structures,respectively.Among them,L-phenylalanine,the precursor of phenolic synthesis,increased with the increase of drought stress,and recovered significantly after rehydration.The content of some phenolic compounds increased,which enhanced the antioxidant capacity of plants and counteracted the negative effects of drought stress.However,the synthesis of some phenolic compounds was hindered by severe drought.In conclusion,the response of saponifia seedlings to drought stress and rehydration is jointly completed by a variety of internal physiological,biochemical and metabolic regulation.Severe drought will cause certain damage to saponifia seedlings,causing growth and metabolism obstacles.Although saponifia seedlings have certain tolerance to drought stress,high-intensity stress will cause irreversible damage to the plant itself. |
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