Application Of Ethephon Impact Zoysiagrass Responses To Cold Stress

In this study,zoysiagrass was used as the test material.After figuring out the optimum spray concentration of ethephon in the field,which is 3500ml/m3 and 300mg/L,the zoysiagrass was treated with ethephon to analyze the effect of ethephon under the low-temperature stress.Real-time PCR was used to verify the effect of ethephon on the relative expression of four antioxidant enzyme genes under low-temperature stress.Finally,the differently-expressed genes of ethephon treatment under cold stress were filtered by transcriptome analysis to find out the genes related to cold tolerance,and then predict the mechanism of zoysiagrass in response to low-temperature stress.This study provides a basis for the transcriptome analysis of ethephon affecting the low-temperature tolerance of zoysiagrass.It also lays a foundation for exploring the molecular mechanism of ethephon response to low-temperature stress by cloning related genes and genetic improvement.The main results are as follows:(1)In this study,figuring out the optimum spray concentration of ethephon in the field,which is 3500ml/m3 and 300mg/L.(2)Ethephon treatment of plant leaves significantly impaired the increase of EL and MDA content under cold stress.The transcriptome DGEs analysis showed that ethephon promoted up-regulation of cellulose synthase gene expression and down-regulation of glycosyl hydrolase gene expression,which was conducive to maintaining cell wall structure stability and resisting low temperature.(3)Ethephon treatment alleviated the chlorophyll degradation,reduced carbon sequestration and energy dissipation under cold stress,and improved the ability of Zoysia to resist low temperature.(4)Ethephon treatment of leaves promotes the tendency of cells to synthesize and accumulate proline and soluble sugar without accumulating soluble protein,slowing down amino acid metabolism and enhancing the cell osmotic adjustment ability to prevent death caused by dehydration under cold stress.(5)Ethephon has different response pathways to different antioxidant enzymes.Ethephon affects SOD,CAT and POD activities by oxidative stress under cold stress,while increasing level of APX activity does not require oxidative stress.(6)Ethephon may up-regulate the expression of cytSOD,FeSOD and chlSOD genes at the transcriptional level to increase the SOD activity of zoysiagrass under cold stress.Changes in CAT and POD activity may be regulated by post-transcriptional levels,but specific regulatory mechanisms remain to be explored.(7)Ethephon promotes the synthesis of ABA,GA and other hormones under cold stress,inhibits the signal transduction response of ABA,GA,JA and other hormones,avoids excessive energy consumption and improves cold resistance.(8)The transcriptome sequencing of each treatment group was carried out,and a total of 98.43G clean date was obtained.The differential expression analysis was performed on the sequencing results of spraying ethephon and distilled water without low temperature stress.A total of 2231 DEGs were found.GO functional annotation analysis showed a total of 588 DEGs annotated into 719 GO terms of three categories of biological processes,cell composition and molecular function.The comparison results of DEGs with KEGG database showed that 220 DEGs were enriched in 96 KEGG pathways.DEGs of plant hormone signal transduction,carbon metabolism and amino acid biosynthesis pathway had the greatest proportion.