Study On Physiology And Differential Expression Genes Responding To Al Of Elephant Grass Roots And Identification Of MATE Family

Aluminum is the most abundant metal element in the earth’s crust.With the increase of soil acidity,Al toxicity has gradually become the main factor limiting crop growth in acidic soil.Elephant grass（Cenchrus purpureus）is a perennial C4 grass of Gramineae.It is an excellent forage and energy grass widely cultivated in tropical and subtropical regions.At present,the phenomenon of soil acidification in the main planting areas of elephant grass is becoming more and more serious,and the growth of crops including elephant grass is seriously limited.However,the molecular response mechanism of elephant grass under Al stress is still unclear.This study analyzed the phenotypic changes and physiological characteristics of elephant grass under Al treatment,combined with transcriptome analysis to identify the key pathways and important genes of root response to Al,and further identified and analyzed the MATE family to verify the function of core genes in response to Al.The main results are as follows:1.The concentration range of elephant grass tolerance to Al³⁺was defined.When the concentration of Al Cl₃ was 0.2 mmol/L,the growth of elephant grass was promoted.When the concentration of Al Cl₃ was 1 mmol/L,the growth of elephant grass was inhibited.When the concentration of Al Cl₃ was more than 10 mmol/L,the leaves of elephant grass were chlorotic and withered.The critical concentration of Al³⁺tolerance of elephant grass was 7.5～10 mmol/L.In response to Al stress,the elephant grass root system mainly activates the antioxidant system,increases the ability to scavenge reactive oxygen species,and secretes a large amount of citric acid to chelate Al³⁺,thereby reducing cell damage.2.The key metabolic pathways and core genes of elephant grass roots in response to Al were identified.Transcriptome analysis identified 33,466 differentially expressed genes.KEGG enrichment analysis showed that most of the genes were significantly enriched in key metabolic pathways such as glycolysis/gluconeogenesis,tricarboxylic acid cycle and anti-cyclic acid and aldehyde acid metabolism.We further identified 864MATE-based transporters and 1,214 MYB-based transcription factors that were differentially expressed after Al treatment.WGCNA analysis identified Al-responsive core genes including CpMATE93.3.At the genome-wide level,185 CpMATE genes were identified and divided into four groups included C1,C2,C3 and C4.The expression of the Al-responsive core gene CpMATE93 was significantly increased under severe stress,and overexpression of CpMATE93 significantly enhanced the Al tolerance of yeast cells.The genetic transformation system of elephant grass mediated by Agrobacterium tumefaciens was preliminarily established,and the overexpression lines and RNAi interference lines of CpMATE93 gene were obtained,which laid a foundation for the analysis of Al-tolerant mechanism and the creation of Al-tolerant germplasm.