Identification Of Rice MYB Transcription Factor Family Members And Mechanism Of Their Stress-Resistant Regulation

Rice(Oryza sativa L.)is one of the most important food crops and more than half of the world's population feeds on it.In order to ensure world food security,rice producers need to consider various stress factors that may lead to rice yield reduction and find ways to cope.However,the regulation mechanism of rice against many external stresses is still an unsolved mystery,which makes it extremely difficult for rice producers to find ways to deal with rice yield reduction.Many studies have shown that v-myb avian myeloblastosis viral oncogene homolog(MYB)transcription factors are involved in the stress response process in plants.Therefore,it is very important for the disclosure of the rice stress resistance mechanism to study the mechanism of rice MYB transcription factor family in response to external stress.It provides theoretical guidance for rice producers to find methods for stress reduction,which is of great significance to the safe production of rice.In this study,all MYB transcription factor family members were firstly identified from the rice genome and their chromosome location was analyzed.Then the rice cultivar Nipponbare was used as the material and the transcriptome sequencing data of Nipponbare under different stresses were downloaded as a sample to analyze the expression characteristics of different members of the MYB transcription factor family in rice under biotic and abiotic stresses.At the same time,the MYB family members that responded to biotic stress,abiotic stress and two types of stress respectively were screened and tested.The specific results are as follows:1.At first,175 candidate gene sequences of rice MYB transcription factor family were obtained by searching the key word "MYB" in rice genome.Then according to the characteristic domain of the MYB family,three different online tools,HMMER,NCBI-CDD and SMART,were used to identify members respectively.The results showed that 158 MYB family candidates were identified by HMMER,137 MYB family candidates were identified by SMART and 150 MYB family candidates were identified by NCBI-CDD.A total of 151 members of the MYB transcription factor family were obtained after cross-validation of the three tools.Chromosome location analysis found that 28 MYB transcription factors were located on chromosome 1,accounting for the highest proportion of 18.54%.Moreover,MYB family members are distributed on all 12 chromosomes of rice.2.The results of RNA-seq data analysis of rice transcriptome under different stresses obtained by download showed that 25 MYB family members responded to abiotic stress and 14 MYB family members responded to biotic stress.In addition,there were 3 MYB members,namely Os10g0562100,Os05g0140100 and Os11g0700500,whose expression levels were down-regulated under both biotic and abiotic stress.Only one MYB member,Os10g0478300,was up-regulated under both biotic and abiotic stress.3.The gene chip data of 2025 rice transcriptome under different stress conditions were used to further explore the regulatory mechanism of the rice MYB gene Os11g0700500,which was down-regulated under the above-mentioned stress conditions.By using gene co-expression analysis technology,it was found that Os11g0700500 gene might involve defense response,phenylpropanoid biosynthesis and hydrogen peroxide catabolic process,which indicated that the rice MYB gene Os11g0700500 could indeed participate in the response to stress resistance.Subsequent correlation analysis showed that the rice MYB gene Os11g0700500 was strongly correlated with Os06g0714600 gene,while Os06g0714600 was a negative regulatory gene in the brassinolide metabolism pathway.The promoter sequence of Os06g0714600 gene was confirmed to have multiple binding sites of MYB transcription factor and the binding sites of MYB transcription factor Os11g0700500 was obtained in its sequence.Meanwhile,the GUS staining test also proved that the first 3000 bp sequence of the Os06g0714600 gene had promoter function.Therefore,it is believed that the Os11g0700500 gene of the rice MYB family member regulates the transcription and expression of Os06g0714600 gene by binding to the promoter region upstream of Os06g0714600 gene,thereby affecting the metabolism of brassinolide and regulating the stress resistance of rice plants.