Symbioses of Endophytic Fungi and Subsequent Physio-Chemical Changes in Grapevine Leaves from Two Cultivars

The metabolic impacts of endophytes on grape cells have been addressed in many studies. However, to date, no reports have investigated these phenomena in vine leaves, which also permit examination under well-controlled whereas more represent the situation of endophytes within grapevines. In the current work, we first established a method to test the symbiotic efficiency of fungal endophytes in vitro using aseptic grapevine (Vitis vinifera L.) leaves. Next, we compared the symbioses of varied fungal strains as well as physio-chemical changes triggered by these symbioses, in grapevine leaves from two different cultivars ‘Rose honey’ (RH) and ‘Cabernet sauvignon’ (CS). Our results demonstrated that all the tested fungal strains were able to achieve successful infection and symbiosis in leaves from both cultivars. The symbiotic efficiencies of the tested fungi in grapevine leaves varied considerably from one fungal strain to another, perhaps due to host-selectivity. Concerning the cultivars, most of the fungal strains that were tested appeared similarly detrimental and similar symbiotic rates between leaves of the two cultivars. Meanwhile, the symbioses of most fungal strains clearly promoted the detected physio-chemical traits compared to the control. Most of these fungal strains, such as RH7, RH12, RH32, and others, conferred greater physio-chemical effects in RH leaves than in CS leaves. Several fungal strains (RH34, RH49 and MDR36) exhibiting high symbiotic efficiency and lower host damage, while initiating greater physio-chemical responses in grape leaves of both cultivars, may potentially be developed for further applications. The results of this study demonstrate that, in addition to grape cells, grape leaves are also able to respond metabolically to endophytes, and also provide a more efficient approach to select candidate endophytes for grape quality management in viticulture.