Analysis Of The Role Of GmMATE13 In Aluminum-induced Citrate Secretion From Soybean Roots

Aluminum?Al?toxicity is one of the main factors that restrict crop yield on acid soil.Soybean is widely cultivated as an important cash crop in the world.Mechanism of aluminum resistance of soybean is of importance to Al resistance cultivar breeding..Our previous studies has characterized three genes encoding citrate transporters?MATE?respectively as GmMATE75,GmMATE79,GmMATE87.None of them were specificially induced by Al stress and specially expressed in the root tip.Thus,it is necessary to further mining more citrate transporter for more effecient and specity in response to Al stress..Based on previous work and bioinformatics analysis,this study focused on GmMATE13,another gene encoding citrate transporter.The main experimental results were as follows:1.Analysis of the role of GmMATE13 in aluminum-induced citrate secretion from soybean roots?1?Bioinformatics analysis found that GmMAET13 contained 12 transmembrane domains,and its homology with GmMATE79,GmMATE87,GmMATE47 and GmMATE75 are 50.36%,56.19%,51.75%and 49.64%respectively,Its homology with GmMATE58 is 94.81%.It is also closely related to other citrate transporters such as EcMATE3,ZmMATE1 and ZmMATE2.?2?Transcriptional expression pattern analysis of GmMATE13:during 24-hour,the expression of GmMATE13 increased with Al treatment duration in the aluminum-sensitive soybean cultivar JiYu62;the expression of GmMATE13 peaked at 8 h Al treatment duration then decreased in the aluminum-resistant soybean cultivar JiYu70.Higher expression of GmMATE13 were found at basal root tissues?2-3cm?than that in root tips?0-1cm?.The expression of GmMATE13 was significantly increased by aluminum treatment,while inhibited by La and Cd treatment.The expression of GmMATE13 was not affected by Fe deficiency treatment.?3?The transient expression vector of GmMATE13-GFP was transformed into the protoplast of Arabidopsis thaliana,the laser confocal microscopy observation showed that GmMATE13 was localized on the plasma membrane.?4?GmMATE13 was overexpressed in soybean roots?GmMATE13-OE?with 35S as the promoter.After Luciferase and transcriptional expression detection,it was confirmed that the expression level was slightly increased.The citrate secretion rate increased under Al treatment or not within GmMATE13-OE soybean roots compared with WT?k599-induced?ones.However,GmMATE13-OE root tips did not decrease its Al content..GmMATE13 was overexpressed in Col4 of Arabidopsis thaliana using 35S as the promoter,and the phenotype was observed under aluminum treatment.When Al treatment concentrations were 50?M or above,compared with Col4,GmMATE13-OE strain was more sensitive to Al.GmMATE13-OE strain showed improved Al resistance under 25?M AlCl₃ treatment.?5?The interaction between GmSTOP1a and GmMATE13 was studied by luciferase reporter gene experiment,and it was found that GmSTOP1a had an obvious regulatory effect on GmMATE13.2.Analysis of transcription expression differences of GmMATE13?1?Collect soil from four areas including LiangCheng in Inner Mongolia province,changchun in Jilin province,changsha in Hunan province,lishui in wenzhou.The exchangeable aluminum,iron,and pH of these four soil showed a larger difference.JiYu70 was planted in the four soil,found that GmMATE13 was mainly expressed in the roots,minor expression was also found in stem and leaves.GmMATE13transcriptional expression may be affected by Al or iron supply,may also affected by other soil factors.?2?The transcriptional expression of GmMATE13 under Al stress was not significantly correlated with aluminum content within thirty soybean cultivars collected from nation wide.In conclusion,GmMATE13 encoded a citrate transporter in soybean,which is regulated by GmSTOP1a and responsible for the secretion of part of citrate under Al stress.Its regulatory mechanism and its function in the Al resistance mechanism still need further analysis.