The Dorylaimid family Longidoridae in Portugal: 15 years late

Abstract

Dagger and needle nematodes are one of the main group of parasitic nematodes in grapevine worldwide. They cause severe damage to plants by their direct feeding and, in addition, some species can transmit plant viruses. Grapevine fanleaf virus (GFLV) is transmitted by Xiphinema index and it is the main responsible for a progressive degeneration of grapevines which occurs in most vineyards worldwide. This research area has been deserted for over fifteen years in Portugal. The main objective is to determine the occurrence and distribution of longidorid species from vineyards in Portugal. Surveys are being conducted since 2015 on representative vineyards. A strategy based on the combination of morphometric and morphological characterizations with molecular analysis using ribosomal DNA segments (rDNA) (D2–D3 expansion regions of the 28S gene, ITS1 region, and 18S gene) and a segment of a mitochondrial DNA (mtDNA) (cytochrome c oxidase 1 subunit or COI) were used for identification of longidorids. Severe longidorid infestations were found in grapevine soils, highlighting X. index by its phytopathological importance. Longidorid nematodes detected, in order of decreasing frequency of total soil infestation were Xiphinema pachtaicum, X. index, X. italiae, and Xiphinema sp. Disease symptoms were observed on aboveground plant parts of the infected grapevines with X. index, displaying a yellow mosaic pattern in leaves characteristic of infections by GFLV