Study On The Drought Tolerance Mechanism Of Populus Euphratica Seed Germination And MYB Gene Family Based On Transcriptome

Populus euphratica Oliv.is mainly distributed in Xinjiang and other places in our country,and it plays an irreplaceable role in stabilizing the ecological balance of the desert river zone in the extreme arid region of Xinjiang.Seed germination is a stage of plant growth and development,which is of vital importance to plant reproduction and population maintenance,expansion and recovery.In arid desert areas,precipitation is scarce and evaporation is strong.The seeds of desert plants often use their special germination mechanism to ensure the germination of seeds and the growth and development of seedlings at the right time and place,so as to ensure survival and reproduction under extreme environmental conditions.MYB transcription factor family is one of the most numerous transcription factor families in plants,and it is widely involved in the regulation of physiological processes such as plant growth and development,metabolism,hormone response,biotic and abiotic stresses.Based on the published genome data of P.euphratica,this study carried out the germination of the seeds of P.euphratica treated with drought and hormones as materials,transcriptome and variable shear analysis were carried out,and based on the transcriptome data,the prediction of drought resistance genes of P.euphratica MYB transcription factor family was carried out.;Obtain the following main research results:(1)Transcriptome analysis of P.euphratica under drought and hormone conditions during germination period.The transcriptome test data of the three treatment groups of PEG,ABA,and GA P.euphratica seeds were obtained and compared with the control group.Through the screening of DEGs,it was found that in the PEG-VS-CK comparison group,there were 4230 DEGs up-regulated and 3385 DEGs down-regulated;in the ABA-VS-ABA_CK comparison group,2858 DEGs up-regulated and 4803 DEGs down-regulated.In the GA-VS-GA_CK comparison group,there were 1040 up-regulated genes and 1276 down-regulated DEGs.Through the enrichment analysis of DEGs GO,it is speculated that the drought-tolerant genes of P.euphratica seeds regulate their growth by regulating the content of ABA,and the genes in the seeds of P.euphratica treated with GA hormone regulate the germination and dormancy of the seeds of P.euphratica by regulating the content of ethylene.Transcription factor analysis found that a high number of MYB,AP2-ERF>-ERF transcription factor family members were identified in the DEGs in each comparison group.Therefore,it is inferred that MYB and AP2-ERF>-ERF play an important role in response to drought stress and hormone induction of P.euphratica.(2)Alternatively Spliced analysis(AS)of P.euphratica under drought and hormone conditions during germination period.We found that 6 groups of P.euphratica seed samples including PEG,CK,ABA,ABA_CK,GA,and GA_CK had 11,239 AS in 4893 genes.Among them,the frequency of RI events was the highest,indicating that RI-type AS events may be possible P.euphratica seeds have certain biological effects in drought resistance and hormone regulation.The number of DEGs and DASGs in each comparison group is very small,and the predicted GO pathways are also different.Therefore,it can be speculated that the genes expressed by P.euphratica may be independently regulated by two kinds of gene differential expression and variable splicing Forms to respond to drought and hormone pathways.(3)P.euphratica MYB transcription factor family analysis.Through gene family identification of the Populus euphratica genome,304 MYB transcription factors were obtained,including 4 types: MYB-related(119),R2R3-MYB(174),3R-MYB(3),4R-MYB(1).The analysis of the above-mentioned MYB transcription factor family members showed that Pe MYBs is distributed on 18 chromosomes except chromosome 13;R2R3-MYB transcription factors may be involved in growth and development.Physiological processes such as metabolism and stress;Drought resistance candidate genes(Pe MYB29,Pe MYB30,Pe MYB128)in MYB transcription factor family were screened to provide references for drought resistance breeding.