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The impact of the grapevine trunk disease fungus Lasiodiplodia on the physiological responses of different grapevine cultivars

Pedro Reis: Instituto Superior de Agronomia, LEAF, Universtiy of Lisbon

<div>There is still little information about the effective risks that <em>Lasiodiplodia </em>spp., particularly <em>Lasiodiplodia theobromae,</em> pose to vineyards or how different cultivars respond to pathogen attack. To better understand the impact of <em>Lasiodiplodia</em> spp. on grapevine physiology, two-year-old potted plants of four Portuguese varieties, Aragonez (=Tempranillo), Touriga Nacional, Touriga Franca and Alvarinho, were inoculated with six <em>L. theobromae, </em>from different geographic origins, and one <em>L. mediterranea </em>isolates, which are responsible for causing diverse symptoms, including bud necrosis and perennial cankers. Plants were kept in a greenhouse under controlled conditions and the effects on plant physiological processes such as water relations, photosynthetic performance and defence mechanisms, were measured after 10 weeks. Leaf water potential, leaf gas exchange and chlorophyll fluorescence were assessed, and leaf samples were collected to assess malondialdehyde (MDA) and proline contents. Results indicate that cultivars had different responses towards pathogens inoculation, with a general tendency towards water potential decrease and increase of proline content, while photosynthetic activity and MDA content varied amongst the tested cultivars. These differences might be related with host-pathogen interaction, suggesting that the cultivar and the inoculum aggressiveness might play specific roles regarding <em>Lasodiplodia</em> spp. in grapevines that have to be considered.</div>