Regulation Yield And Quality Of Mung Bean By DCPTA And Carbon Metabolism Mechanism Research

Mung bean（Vigna radiata）has a good edible and medicinal value,and its demand is increasing at a global scale.Yet due to the relatively backward production management,its output level is generally low,restricting the further development of China’s mung bean industry to a certain extent.As a result,the import volume is far greater than the export volume.Therefore,how to increase the yield and quality of mung bean under the unchanged condition of the original planting area has become an important scientific research topic.Previous studies have reported that 2-（3,4-dichlorophenoxy）-triethylamine（DCPTA）could be absorbed by plant stems and leaves to promote its photosynthetic capacity and growth,improving crop yield.Here,this study was to clarify the regulatory effect of DCPTA on the yield and quality of mung bean.The main varieties（in the Northeast）JL10 and BL11 were used as test varieties,and we further carried out a combination of three years of pot experiment and two years of field experiment and foliar spraying at the first flowering stage.Firstly,the optimal concentration of DCPTA at the first flowering stage was determined using the yield;the 30germplasm resources were treated with DCPTA and DCPTA,while residues were detected to further confirm the effectiveness and safety of the dosage.Secondly,on this basis,we further carried out the confirmation of yield in both pot and field using the quality analysis and the regulation of DCPTA on mung bean morphological indicators,endogenous hormones,antioxidant enzyme activities,photosynthetic physiology,starch-sucrose metabolic pathways and key metabolic enzyme genes.The main results were as follows:1.According to experimental results from the effect of four different concentrations of DCPTA(20,40,60,and 80 mg·L^-1)on mung bean yield,we found that foliar spraying with 40mg·L^-1DCPTA at the initial flowering stage had the best effect on the yield of mung bean.The verification results on 30 germplasm resources of mung bean showed that DCPTA increased the average yield efficiency of mung bean by 73.33%.DCPTA residue was detected in JL10,BL11and 30 mung beans treated with DCPTA,while no DCPTA residue was detected(the detection limit was below 0.11μg·kg^-1).2.In the two-year experiment,40 mg·L^-1DCPTA treatment significantly increased the yield of two varieties of mung bean.DCPTA treatment did not significantly affect the 100-grain weight and the seed per pod,but it significantly increased the number of seed and pod per plant.In terms of mung bean quality,DCPTA treatment increased the protein content in mung bean grains,but it had no significant effect on starch content,fat content and components of fatty acid（palmitic acid,stearic acid,oleic acid,linoleic acid and linolenic acid）.DCPTA treatment increased the contents of Fe,Mn,P and Se in mung bean grains but decreased the contents of K and Na.3.DCPTA had a better effect on increasing the agronomic and physiological characteristics of mung bean.Plant height and leaf area of mung bean were increased by 40 mg·L^-1DCPTA treatment,then improving the dry matter weight of plants.DCPTA treatment enhanced the SOD,POD and CAT activities,as well as the IAA,ZR and GA₃contents,but decreased the ABA content.Meanwhile,it also significantly increased chlorophyll content,chlorophyll fluorescence parameters（Fv/Fm,Fv/Fo,ΦPSII and ETR）and photosynthetic gas exchange parameters（Tr,Gs）of mung bean,as well as Pn.4.Transcriptome analysis of mung bean leaves sprayed with DCPTA showed that the main genes that were involved in carbon metabolism,such as photosynthesis,starch and sucrose metabolism,were up-regulated.The expression of sucrose synthase,fructokinase andβ-fructofuranosidase（invertase）was verified by RT-q PCR,the expression trend of which was the same as RNA-Seq,proving that starch and sucrose metabolism pathway was one of the candidate pathways to improve mung bean yield in response to DCPTA.5.According to the physiological verification and analysis of differential expression gene,it showed that the content of carbohydrates and activities of enzymes related to glucose metabolism were increased in different mung bean tissues after DCPTA treatment;the contents of soluble sugar,sucrose,starch,SS,SPS and AI in leaves were increased;and the sucrose content and related enzymes in pod and seed were also increased.6.Two kinds of Arabidopsis were sprayed 40 mg·L^-1DCPTA(including wild-type Col-0,carbon metabolism gene missed Arabidopsis mutants SALK＿206355C（AT3G07320,T1B9.1）,SALK＿014462C（AT4G25000,AMY1）and SALK＿200339C（AT1G17600,F1L3＿30）at the initial flowering stage;we found that the yield and pods per plant of wild-type Arabidopsis were increased by 13.20%and 13.19%,respectively.However,both the yield and pods per plant of SALK＿206355C and SALK＿014462C mutants were not increased significantly.The soluble sugar and sucrose contents were increased significantly in wild-type Col-0 by DCPTA treatment;the activities of SS and AI were significantly increased,but there was no significant effect on SALK＿206355C and SALK＿014462C mutants.These finding further indicate that starch and sucrose metabolic pathways can be regulated by DCPTA.