Molecular Mechanism Of Leaf Yellowing Of Areca Plam Based On Transcriptome Sequencing

As an important economic crop in Hainan Province,Areca catechu L.has become increasingly serious in its yellowing of leaves,which is a major obstacle to the sustainable and healthy development of the areca plam industry.According to field research,phytoplasma infection,drought and improper use of herbicides can cause yellowing of areca plam leaf,and the yellowing caused by the above three factors is very similar in initial symptoms.In this study,transcriptome sequencing was used to analyze the expression of differentially expressed genes under phytoplasma,drought and herbicide stresses,and differentially expressed genes related to leaf specific yellowing were screened to explore the molecular mechanism of specific yellowing symptoms in areca plam leaves under the above three stresses.The research results are as follows:1.Using Illumina HiSeq platform,321,402 Unigenes were obtained from leaves,whole-leaf yellowing leaves and healthy leaves which showed similar yellowing symptoms under drought,herbicide and phytoplasma stress.60.66%of Unigenes did not match any annotation information in the six databases,indicating that the current research on areca genome is not deep enough,the proportion of genes with unknown functions is large,and has strong excavation for new gene functions.2.By comparing the results of transcriptome sequencing in the experimental group with those in the healthy control group,654 differential genes co-expressed in the specific leaf yellowing group and the whole leaf yellowing group were screened,and 440 differential genes co-expressed were only found in the specific leaf yellowing group.GO arnotation and KEGG enrichment showed that the differentially expressed genes related to leaf yellowing were mainly concentrated in secondary metabolic pathways,hormone signal transduction pathways and energy metabolism pathways.The significant up-regulation of SAUR,JAZ and ERF1 in auxin,jasmonic acid and ethylene signal transduction pathway may play an important role in the regulation of areca plam leaf yellowing symptoms.However,the differentially expressed genes in specific yellowing samples were specifically annotated to the signal transduction and synthesis pathway of brassinolide,indicating that this pathway may play a key role in regulating the specific yellowing symptoms of areca plam leaves.3.The differentially expressed genes in specific yellowing samples were mainly concentrated in metabolic pathways and secondary metabolic pathways.The differentially expressed genes in brassinolide signaling pathway,flavonoid biosynthesis pathway and phenylpropane biosynthesis pathway were significantly up-regulated,while the down-regulated genes in brassinolide biosynthesis pathway were significantly down-regulated,which may play an important role in regulating the specific yellowing symptoms of areca plam leaves under phytoplasma,drought and herbicide stress.4.Four differentially expressed genes which may play an important role in regulating specific yellowing of areca plam leaves were selected from the specific yellowing samples for real-time fluorescence quantitative PCR(qRT-PCR).The results were consistent with the expression trend of transcriptome sequencing results.Therefore,the results of transcriptome sequencing are accurate and reliable.