Potato is the third most important crop in the world after rice and wheat, with a great social and economic importance in Portugal as it is grown throughout the country, including the archipelagos of Madeira and the Azores. The tropical root-knot nematode (RKN) Meloidogyne luci is a polyphagous species with many of its host plants having economic importance and the ability to survive in temperate regions, which pose a risk to agricultural production. In 2019, M. luci was detected from soil samples collected from the council of Santo António in Pico Island (Azores). Bioassays were carried out to obtain females, egg masses, and second-stage juveniles to characterize this isolate morphologically, biochemically, and molecularly. The observed morphological features and morphometrics showed high similarity and consistency with previous descriptions. Concerning the biochemical characterization, the esterase (EST) phenotype displayed a pattern with three bands similar to the one previously described for M. luci and distinct from M. ethiopica. Regarding the molecular analysis, an 1800 bp region of the mitochondrial DNA between cytochrome oxidase subunit II (COII) and 16S rRNA genes was analyzed and the phylogenetic tree revealed that the isolate grouped with M. luci isolates (99.17%). This is the first report of M. luci parasitizing potato in the Azores islands, contributing additional information on the distribution of this plant-parasitic nematode.
Considered one of the most devastating plant parasitic nematodes worldwide, Meloidogyne spp. (commonly known as the root-knot nematodes (RKNs)) are obligate sedentary endoparasites that establish in the roots, causing hyperplasia and hypertrophy of surrounding cells, triggering the formation of galls. These galls will affect root development and physiology, leading to substantial yield losses. During 2017–2022, an extensive survey of Meloidogyne species was undertaken in Portugal (mainland and islands). A total of 1,071 samples were collected by the National Plant Protection Organization (DGAV) and private farmers from different regions of the country and were analysed at the Laboratory of Nematology (NemaINIAV). Samples in which the presence of Meloidogyne sp. was detected were used to perform bioassays to obtain females and juveniles for further studies. Since the accurate identification of RKNs is an important aspect of crop management, morphological and biochemical characterisation was performed. The most common morphological features were observed, showing consistency with previous descriptions of the genus. The biochemical identification using the esterase (EST) phenotype revealed the phenotypes of Meloidogyne arenaria, M enterolobi, M. hispanica, M. hapla, M. incognita, M javanica, and M. luci. Meloidogyne incognita and M. javanica were found to be the most prevalent species in the different regions followed by M. arenaria and M. hapla. This is the first distribution report performed in Portugal on RKNs, contributing to the development of management strategies and to updated information on the status of these pests in Europe.
Root-knot nematodes (RKNs), Meloidogyne spp., are a group of plant-parasitic nematodes (PPNs) of great economic significance worldwide. The northern root-knot nematode, Meloidogyne hapla, is one of the most important species of RKNs occurring in cold regions. In Portugal so far, M. hapla has been found parasitizing potato and fig trees. During surveys carried out in 2019–2022 in fields for horticultural and ornamental production, soil and root samples were collected. Roots were observed under a stereomicroscope to determine the presence of galls. Nematodes were extracted from the soil. Morphological features showed a high similarity and consistency with previous descriptions of the genus. For molecular analysis, total genomic DNA was isolated from single nematodes and used to amplify in multiplex reaction using the species-specific primers JMV1, JMV2 and JMVhapla, and for sequencing of the ITS region with the primers TW81/AB28. Multiplex PCR amplification produced a specific fragment of 440 bp and PCR amplification of the ITS region yielded a single fragment of 550 bp, as expected. The obtained sequences showed a similarity ranging from 99.8% to 100% with the sequences of M. hapla available in the database. The phylogenetic tree revealed that the isolates grouped with M. hapla isolates. From the 690 samples collected, M. hapla was detected in three different hosts (grapevine, eucalyptus and potato) in four districts of mainland Portugal and on Madeira Island. To our knowledge, this is the first report of M. hapla infecting the grapevine and eucalyptus in Portugal.
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