Pathogen development and host responses to Plasmopara viticola in resistant and susceptible grapevines: an ultrastructural study

Abstract

The downy mildew disease in grapevines is caused by Plasmopara viticola. This disease poses a serious threat wherever viticulture is practiced. Wild Vitis species showing resistance to P. viticola offer a promising pathway to develop new grapevine cultivars resistant to P. viticola which will allow reduced use of environmentally unfriendly fungicides. Here, transmission and scanning microscopy was used to compare the resistance responses to downy mildew of three resistant genotypes of V. davidii var. cyanocarpa, V. piasesezkii and V. pseudoreticulata and the suceptible V. vinifera cultivar ‘Pinot Noir’. Following inoculation with sporangia of P. viticola isolate ‘YL’ on V. vinifera cv. ‘Pinot Noir’, the infection was characterized by a rapid spread of intercellular hyphae, a high frequency of haustorium formation within the host’s mesophyll cells, the production of sporangia and by the absence of host-cell necrosis. In contrast zoospores were collapsed in the resistant V. pseudoreticulata ‘Baihe-35-1’, or secretions appeared arround stomata at the beginning of the infection period in V. davidii var. cyanocarpa ‘Langao-5’ and V. piasezkii ‘Liuba-8’. The main characteristics of the resistance responses were the rapid depositions of callose and the appearance of empty hyphae and the plasmolysis of penetrated tissue. Moreover, collapsed haustoria were observed in V. davidii var. cyanocarpa ‘Langao-5’ at 5 days post inoculation (dpi) and in V. piasezkii ‘Liuba-8’ at 7 dpi. Lastly, necrosis extended beyond the zone of restricted colonization in all three resistant genotypes. Sporangia were absent in V. piasezkii ‘Liuba-8’ and greatly decreased in V. davidii var. cyanocarpa ‘Langao-5’ and in V. pseudoreticulata ‘Baihe-35-1’ compared with in V. vinifera cv. ‘Pinot Noir’. Overall, these results provide insights into the cellular biological basis of the incompatible interactions between the pathogen and the host. They indicate a number of several resistant Chinese wild species that could be used in developing new cultivars having good levels of downy mildew resistance.

Isolation and Cultivation of Some Pathogen Fungi from Apple and Grapevines Grown in Arges County

“…Microscope view for Plasmopara viticola revealed a high number of sporangiophores, sporangia and stomata conforming other studies [18][19]. Stomata also constitute natural openings providing direct access to leaf tissue for P. viticola ( fig.…”

Isolation and Cultivation of Some Pathogen Fungi from Apple and Grapevines Grown in Arges County

“…Acknowledgement: This work was supported by a grant of the Romanian Ministery of Research and Innovation, CCCDI-UEFISCDI, Fig. 9 Plasmopara viticola (microscope view) -A, B -Sporangiophores and sporangia,identification according to [18,19] Fig. 7 Conidiophore and emerging asexual conidia, Podosphaera leucotricha -microscope view, identification according to [8,16] Fig .…”

“…In the very rainy years, young resins suffer the most and lead to dramatic decline in production. During autumn, Plasmopara viticola, forms resistance organs that germinate again in spring [4][5][6].…”

MicroRNAs in the response of non-heading Chinese cabbage to Hyaloperonospora parasitica (downy mildew) infection

“…In addition, the number of miRNAs detected at 6 hpi was similar with the number of miRNAs detected at 12 hpi, but the number of differentially expressed miRNAs in response to downy mildew infection was only 1 at 6 hpi compared to 0 hpi while 7 at 12 hpi (Table 3). Since the germination time of downy mildew spores vary [34,35], we assume that the state of spores at 6 hpi and 12 hpi were different.…”