The Mechanism Of ABA In Alleviating The Damage Of Glyphosate In Rubber Tree And Its Application

Glyphosate is one of the most commonly used herbicides in the rubber tree planting process.It causes leaves to be deformed or falled due to pesticide drift.ABA has the function of enhancing the stress resistance of plants,however,stress resistance mechanism of ABA in rubber tree to glyphosate is still unclear.In order to study the regulatory mechanism of ABA on glyphosate damage to rubber tree,plant physiology,molecular biology and bioinformatics techniques were used to analyze the alleviation effect of spraying ABA on rubber trees with glyphosate damage.The relevant members of ABA signaling pathway were comprehensively searched and identified in rubber tree genome database,and gene expression patterns of gene family members under glyphosate stress and ABA treatment were analysed.The results are as follows:1.200 ?mol·L-1 ABA was sprayed on 200 ?mol·L-1 glyphosate-treated rubber tree seedlings.It was found that ABA can effectively alleviate the harm of glyphosate in rubber tree.2.6 HbSnRK2 members were cloned from rubber tree leaves.HbSnRK2.4 belonged to Group I subfamily,HbSnRK2.2,HbSnRK2.6 and HbSnRK2.7 belonged to II subfamily,and HbSnRK2.3a and HbSnRK2.3b belonged to subfamily III.Gene structure analysis showed that HbSnRK2 protein has a conserved N-terminal region and a various C-terminal sequences.The promoter regions of 6 HbSnRK2 genes contained a large number of regulatory elements that respond to hormones and stress stimuli.Their amino acid sequences contained a total of nine motifs.The expression of 6 HbSnRK2 genes was tissue-specific,and the up-regulated folds under ABA treatment were higher than those under other hormone treatments.They were down-regulated by drought,most of them responded to powdery mildew and high-temperature stress;and the III subgroup genes were highly induced by glyphosate.The induction was significantly upregulated and regulated jointly by glyphosate and ABA treatment.3.95 PP2C genes in rubber tree were identified.All these genes contained PP2C phosphatase domain and were phylogenetically divided into 13 subfamilies(A-M).11 motifs were found.Quantitative real-time PCR analysis showed that HbPP2C genes were widely responded to glyphosate and ABA treatment,especially the A subfamily HbPP2C members which showed the most obvious upregulation under glyphosate and ABA treatment.4.85 rubber tree bZIP genes were identified and classified into 10 subfamilies based on their genetic relationship with Arabidopsis and rice.These genes contained 10 motifs.qRT-PCR analysis showed that HbbZIP genes was differentially expressed under the treatment of glyphosate and ABA.HbbZIP68 was significantly up-regulated under glyphosate treatment and was simultaneously induced by ABA.In summary,exogenous ABA could alleviate the phytotoxic effects of glyphosate on rubber trees and increased the stress resistance of rubber trees.Differential response mechanism of HbSnRK2s,HbPP2Cs,and HbbZIPs members of the ABA signaling pathway showed that the HbSnRK2 subfamily III genes were closely related to ABA,the A subfamily bPP2C genes was associated with glyphosate resistance,and HbbZIP68 was glyphosate specific.This study laid a theoretical foundation for studying the mechanism of ABA signal pathway gene family members on resistance to glyphosate stress in rubber tree,and helpingdevelopment of glyphosate pesticidal protection agent with ABA as a core component.