Identification Of Resistance Of Sesame Varieties To Stem Rot And Functional Analysis Of SiPYL4 And SiTLP Genes

Sesame stem rot is a fungal soil-borne disease caused by Macrophomina phaseolina?Mp?,which poses a serious threat to the yield and quality of sesame.Therefore,it is very important for high and stable yield of sesame to excavate disease-resistant genes,develop and cultivate disease-resistant varieties.In this study,44 sesame varieties from different areas were used to identify the resistance of sesame to stem rot in the field.Two genes SiPYL4 and SiTLP related to resistance to sesame stem rot were selected based on transcriptome sequencing result,the SiPYL4and SiTLP were cloned,and the plant over-expression vector was constructed by Gateway technology.The genetic transformation of Arabidopsis thaliana was carried out,and the transgenic plants were identified for disease resistance.The main results were as follows:1.The resistance of 44 sesame varieties from different regions to stem rot was identified.The results showed that 26 sesame varieties with moderate resistance?MR?accounted for 59.1%of the tested varieties,14 sesame varieties with moderate susceptibility?MS?accounted for 31.82%of the tested varieties,and 2 sesame varieties with high susceptibility?HS?accounted for 4.55%of the tested germplasms.2.The SiPYL4 and SiTLP genes were cloned by homologous cloning.SiPYL4full length 645bp,encoding 215 amino acids,SiTLP full length 681bp,encoding 227amino acids.3.Quantitative fluorescence PCR analysis showed that SiPYL4 was up-regulated in resistant sesame cultivars after treatment with stem-rot bitter stress.The expression level was higher at 36 hours and up-regulated at 72 hours in susceptible sesame cultivars.The expression of SiTLP gene in resistant and susceptible cultivars increased significantly at 12 hours of stress treatment,and peaked at 24 hours of susceptible cultivars.The ROS of SOD,POD,CAT and H₂O₂ also increased with the increase of stress time.4.Overexpression of SiPYL4 and SiTLP in the transgenic Arabidopsis Thaliana displayed a prompt growth compared with the wild-type.After seven days of the MP stress,the wild-type Arabidopsis thaliana had obvious symptoms,and some plants died due to the severe cases.The transgenic plants only had a slight yellowish at the bottom of the rosette.The ROS scavenging ability of transgenic Arabidopsis thaliana was also significantly stronger than that of wild-type Arabidopsis thaliana,so it was speculated that SiPYL4 and SiTLP genes play a key role in Arabidopsis thaliana resistance to Mp.