Excavation Of Key Genes In Response To Low Potassium Stress In Tomato

Potassium is one of the essential nutrients for plant growth and development.Potassium deficiency limits plant growth and yield.Plants can sense signals and maintain appropriate physiological responses to maintain life activities under K~+-deficiency stress.In the long-term evolution process,plants have developed a series of signal transduction mechanisms to help them cope with K~+-deficiency stress.MiRNA is a newly discovered small RNA of about 21bases,which is an important growth and development regulator.Although it has been involved in plant tissue and organ development,hormone signaling,heavy metals,salt,low temperature,drought and other stresses,but there is no relevant research on miRNA regulation of tomato tolerance to K~+-deficiency.In this paper,two tomato strains with different tolerances of K~+-deficiency were used as materials to screen some key miRNA and their regulated target genes under K~+-deficiency in response to stress by using miRNA histology sequencing and transcriptome sequencing.The results provide new research ideas for further use of molecular techniques to improve tomato tolerance to K~+-deficiency.1.It is clear that there are significant differences in root architecture,K~+absorption efficiency,reactive oxygen species(ROS),auxin(IAA)and cytokinin(CK)between the two tomato lines(JZ18 low-K~+-sensitive,JZ34 low-K~+-tolerant),and led to the difference between the two strains on K~+-deficiency.K~+-deficiency stress inhibited the growth of JZ18 lateral roots and root hairs,decreased K~+absorption efficiency,and caused significant accumulation of ROS in roots and leaves.The contents of IAA and CK in roots decreased,IAA/CK ratio decreased,and root formation and development were inhibited.The main roots and lateral roots of JZ34 were not significantly inhibited,and the root hairs of the third-order lateral roots were promoted,under K~+-deficiency stress.2.Using high-throughput sequencing technology,7 miRNAs were selected as members of the conserved family and involved in K~+-deficiency stress,including miRNA156d-5p,miRNA168a,miRNA319a,miRNA319b,miRNA319c,miRNA477-3p and miRNA9472-3p.The two genes,which expressed in the root system are miRNA156d-5p,miRNA168a and miRNA9472-3p;four genes expressed in the aboveground are miRNA319a,miRNA319b,miRNA319c,miRNA477-3p.3.Based on BGISEQ-500 transcriptome sequencing technology,key genes related to K~+-deficiency tolerance in tomato were screened at the transcriptional level.At 12 h and 24 h after K~+-deficiency stress,1936 differentially expressed genes(DEG)in JZ18 and JZ34 were identified.According to the analysis of GO and KEGG pathways,DEGs with significant changes mainly include transcription factors,transporters,kinases,oxidative stress proteins and hormone signal transduction and genes related to glucose metabolism.The results confirmed the induced expression of the response gene in the low K~+signal transduction pathway.The largest DEGs group included up to 110 genes related to oxidative stress.Nineteen ethylene response factors(ERFs)responded to K~+-deficiency.QRT-PCR further validated 20 DEGs closely related to K~+-deficiency stress.4.A combined comparative analysis of the results of RNA-Seq and sRNA-Seq analysis Screening miRNAs(miRNA156d-5p,miRNA9472-3p,miRNA319b)and their target genes.The cleavage site of miRNA156d-5p to SPL3 was further verified by 5'RACE technology.By the studies,the important miRNAs and their target genes involved in tomato regulation of K~+-deficiency response stress were obtained.The research results will provide a theoretical reference for the cultivation of tomato K~+-deficiency tolerance.