Non-contact Physiochemical Responses Of Grape Cells To Fungal Endophytes In Vitro

In order to explore the effects of endophytic fungi on the metabolism and growth of wine grape cells without contacting with host cells and the differences in response of grape cells to different endophytic fungi.In this paper,grape cells and endophytic fungi were dual-cultured in different ways to monitor the physiological responses of grape cells to the non-contacted endophytic fungi under different co-culture time and culture methods.Main findings are as follows:1.The dual-culture system which can be used to investigate the long-distance physiological and biochemical interactions of endophytic fungi on grape cells was successfully established in this study.2.The gro.wth rates of grape cells were obviously inhibited by the dual-cultured fungal endophytes wherever on continuous medium(ChM)or on separate medium(SM).Other phsio-chemical parameters such as the activities of peroxidase(POD),superoxide dismutase(SOD),phenylalanine ammonia-lyase(PAL)and the content of malondialdehyde(MDA),total phenolic(TPh),total flavonoids(TF),total soluble protein(TPr),titratable acid(TTA)and total soluble sugar(TSS)in grape cells were also influenced in different degerees,due to the existence of non-contacted fungal endophytes.Responses of grape cells to fungal endophytes were varied among fungal strains and dual-culture methods(CM or SM).These results implied different diffusible signal molecules from different fungal strains may be released and influenced the the non-contacted grape cells by pathways of air and continuous medium.3.When grape cells were co-cultured with endophytic fungiin different distances with 3 endophytic fungal strains RH12,RH32 and CS11.The growth of Common petri dish separated medium(CPSM)co-cultured grape cells and separated petri dishes but within common space(SPCS)co-cultured grape cells were all inhibited by the co-cultured fungal endophytes.Whereas,when grape cells and fungal strain RH32 co-cultured in two different but connected spaces(DCS),the growth of grape cells was promoted by the co-cultured fungus.Certain degrees of gradient growth and physiochemical influences of endophytic fungi on different distance co-cultured grape cells were detected.The increased growth inhibition effects of fungal endophytes on grape cells along with the duration of co-culture time and the increased fungal biomass were also observed in these experiments.All these results indicated the existence of dose effects of endophytic fungus on grape cells.4.Activated carbon was used to collect volatile substances released by endophytic fungi for GC-MS determination,but no specific substances were detected may due to the lower concentration.In conclusion,endophytic fungi have a certain degrees of impacts on the growth and metabolism of non-contact grape cells in vitro.Different diffusible signal molecules may produced from endophytic fungi and exert effects on the metabolism of grape cells via aerial and continuous medium pathways.The signal substances transmitted by air and medium may be different.All these results revealed some clues toward the mechanism of plant cell-fungal endophytes metabolic interactions.