| Achnatherum inebrians,a perennial bunchgrass in the arid and semi-arid grasslands of northwest China,forms a mutually beneficial symbiotic association with an Epichlo? endophyte.In this study,endophyte-infected(EI)and endophyte-free(EF)A.inebrians plants were grown in pots in a greenhouse at three soil moisture availabilities: drought(D,15%),normal moisture(N,30%)and abundant moisture(W,60%).Through gas chromatography-mass spectrometry(GC-MS)analysis,enzyme linked immunosorbent assay(ELISA),transcriptome analysis and quantitative real-time PCR(qRT-PCR)analysis,the present study was to explore the effect of E.gansuensis endophyte on the leaf cuticular wax,plant hormones,and antioxidant system of A.inebrians plants under the different soil moisture treatments.The main results are as follows:1.Hydrocarbons were the dominant components of leaf cuticular wax of A.inebrians plants.The total cuticular wax content of EI and EF A.inebrians plants under 15% soil moisture was significantly(P<0.05)higher than that under 30% soil moisture.Under 15% soil moisture,the total cuticular wax content of EI A.inebrians was significantly(P<0.05)higher than that of EF A.inebrians.The increase in total wax of EI plants was attributed to the increase of alcohols,while in EF plants,it was attributed to the increase of fatty acids and esters.2.The content of abscisic acid(ABA)and ethylene(ETH)of EI A.inebrians under 15% soil moisture content was significantly(P<0.05)higher than that under 30% soil moisture content,while the content of indole acetic acid(IAA),cytokinin(CTK),gibberellin(GA),brassinosteroid(BR)and salicylic acid(SA)of EI A.inebrians under 15% soil moisture content was significantly(P<0.05)lower than that under 30% soil moisture content.The content of CTK and SA of EF A.inebrians under 15% soil moisture content was significantly(P<0.05)higher than that under 30% soil moisture content,while the content of ABA,ETH and jasmonate(JA)of EF A.inebrians under 15% soil moisture content was significantly(P<0.05)lower than that under 30% soil moisture content.Under 30% soil moisture,the content of IAA,CTK,GA and SA of EI A.inebrians was significantly(P<0.05)higher than that of EF A.inebrians,while the content of ABA and JA of EI A.inebrians was significantly(P<0.05)lower than that of EF A.inebrians.Under 15% soil moisture,the content of ABA,ETH and JA of EI A.inebrians was significantly(P<0.05)higher than that of EF A.inebrians,while the content of IAA,CTK,GA,BR and SA of EI A.inebrians was significantly(P<0.05)lower than that of EF A.inebrians.3.The activity of peroxidase(POD)of A.inebrians under 15% soil moisture content was significantly(P<0.05)lower than that under 30% soil moisture content.The activity of catalase(CAT)and phenylalanine ammonia lyase(PAL)and the content of malondialdehyde(MDA),proline(Pro),glutathione(GSH),ascorbic acid(AsA)and carotenoid(Car)of EI A.inebrians under 15% soil moisture content were significantly(P<0.05)higher than those under 30% soil moisture content.The content of MDA,Pro and GSH of EF A.inebrians under 15% soil moisture content was significantly(P<0.05)higher than that under 30% soil moisture content,while the content of AsA and Car of EF A.inebrians under 15% soil moisture content was significantly(P<0.05)lower than that under 30% soil moisture content.Under 30%soil moisture,the content of Pro,GSH and AsA of EI A.inebrians was significantly(P<0.05)higher than that of EF A.inebrians,while the activity of CAT and PAL and the content of MDA and Car of EI A.inebrians were significantly(P<0.05)lower than those of EF A.inebrians.Under 15% soil moisture,the activity of CAT and PAL and the content of Pro,GSH,AsA and Car of EI A.inebrians were significantly(P<0.05)higher than those of EF A.inebrians,while the content of MDA of EI A.inebrians was significantly(P<0.05)lower than that of EF A.inebrians.4.Epichlo? endophyte and soil moisture content regulated the expression of 13 genes related to cuticular wax biosynthesis and transporters,52 genes related to plant hormone synthesis and signal transduction,and 32 genes related to antioxidant enzymes and antioxidants,with the largest gene numbers related to IAA,JA,POD,and GSH pathways.In conclusion,Epichlo? endophyte enhanced the drought resistance of A.inebrians plants by regulating the expression of genes associated with cuticular wax biosynthesis and transporter pathways,plant hormone synthesis and signal transduction pathways and antioxidant enzyme and antioxidant synthesis pathways,and by changing the total wax content,the relative content of wax compositions,plant hormone content,antioxidant enzyme activity and antioxidant content in the leaves. |
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