Varietal Differences In Endophytic Fungi Population Structure Of Grapevine And The Physio/biochemical Effects Of Endophytic Fungi On Grape Cells

Studies have proved that endophytes impose significant effects on the quality and characteristics of wine grapes.This suggests that we can improve the quality of wine grapes and wines by purposely shaping the communities of endophytic population within grapevines.However,the distribution characteristics of endophyte in vines,the selectivity of different grape species on endophyte,as well as the detailed physiological and biochemical interaction between endophytes and grapevines are not well understood.This greatly limits the effective application of endophyte resources in viticulture.In this study,two local wine and table dual-purpose grape varieties,Rose Honey and Crystal(Vitis.Vinifera L.× V.labrusca L.)from Yunnan province which have grown in the same vineyard were analyzed the spatial distribution of endophytic fungal populations and compared the differences between cultivars.In addition,physiological and biochemical responses of grape cells to co-cultured endophytic fungi were also investigated in this research.Main results are as follows:1.In total 1349 endophytic fungal strains were isolated from 1500 grape leaf patches from three different parts of the two grape varieties.After the morphological and molecular identification,all these fungal strains categorized into 17 genus and 46 species.The dominant fungal genus are Fusarium,Alternaria and Colletotrichum,with the dominant degrees of 31.28%,30.54% and 20.83%,respectively.The least isolated genera these grape varieties were Acremonium,Lecanicillium and Meyerozyma.The more number of species endophytic fungi isolated from the old leaves and mature leaves than young leaves between two varieties at different developmen tal stages,while the endophytes fungi richness and diversity index of mature leaves an d old leaves were higher than those of young leaves.Certain degrees of difference in culturable endophytic fungal flora between two cultivars was found,with the similarity about 69 %,and the similarity at the species level was 72%.These results indicated the existence of grapevine varietal selectivity to its hosted endophytic fungi.2.A model of co-culture between grape callus cells and endophytic fungi was established,and the physio-chemical interactions between different endophytic fungiand grape cells were studied.After 7 days co-culture with grape cells,16 endophytic fungal strains can be classified into different groups by degrees of detriment to grape cells.Among these tested fungal strains,strains D2,D4,D5,D7,D8,D12,D13,D14 and D16 conferred highly detriment to grape cells and D16 had the most serious detrimental effects to grape cells;fungal strains D1,D6,D9,D10,D11 and D15 had moderate detrimental effects to grape cells;whereas,D3 strain had no obvious damage to grape cells.3.Physiological and biochemical impacts of different endophytic fungi strains on the grape cells were furtherly analyzed.Results showed that fungal strains D2,D4,D7,D9,D13,and D16 could all promoted the content of total flavonoids(TF),total phenol(TPh),total protein(TPr)and PAL activity.Among these fungal strains,D2,D4,and D13 greatly promoted the content of TF;D2,D4,D7,D13,and D16 significantly promoted the contents of TPh and TPr;and D2,D7,and D16 had a significant effect on PAL activity.Whereas,D3,D5,D8,D12,D15 can inhibit the accumulation of TF,TPh,TPr and PAL of grape cells.Most of these substances greatly contribute to grape qualities,and closely related to plant defenses.Concerning the tested physiochemical parameters,PAL activity was the most sensitive traits that can be easily influenced in greater ranges by the co-culture of fungal endophytes.Our researches provides basis and methods for screening candidate endophytic fungal strains in viticulture managements.In conclusion,this study has revealed the spatial distribution and varietal differences of endophytic fungi communities of two grape varieties in Yunnan province;isolated and greatly enriched the endophytic fungal resources for our further researches and utilization;and established techniques for the screen of candidate endophytic fungal strain for the further application in viticulture.