Morpho-molecular characterization of Colombian and Brazilian populations of Rotylenchulus associated with Musa spp

Pratylenchus Araucensis (Rhabditida: Pratylenchidae) a Widely Distributed Nematode in Musa Spp. from Colombia

Pratylenchus is one of the most limiting nematodes of Musaceae production in the world. Knowledge of the nematode species is one of the requirements for its management in the field. This study aimed to identify up to the species level Pratylenchus populations associated with plantain and banana crops in the states of Caldas, Quindío, and Valle del Cauca in Colombia. In these regions, Pratylenchus has been reported to affect these crops in the past, but with records of the nematode only up to the genus level. For this purpose, five populations of Pratylenchus extracted from samples composed of roots and rhizospheric soil, four from plantain and one from banana, were identified through morphological, morphometric, and molecular analysis (sequencing of the D2-D3 of rRNA and cytochrome oxidase subunit I of mtDNA). All populations were identified as P. araucensis, a species reported previously in eastern Colombia, and one that the present study found in the center and southwest of the country, indicating that this species of nematode is widely distributed in the Musaceae-producing areas of Colombia. The present study reports the first COI mtDNA sequences for this species of nematode.

Characterization of Pterotylenchus cecidogenus in Desmodium ovalifolium cover crop from oil palm plantations in central Colombia

Until recently, the stem gall nematode Pterotylenchus cecidogenus was only registered in eastern Colombia. However, the disease has recently been observed in central Colombian oil palm plantations that use Desmodium ovalifolium as a cover crop. Soil, root, stem, and leaf samples were collected from D. ovalifolium. Plants showed foliar yellowing, leaf drying, and galls within stem nodes. Nematodes were identified, and the distribution, population density, and relative importance of different genera were determined. We performed morphometric and molecular identification of nematodes associated with gall symptoms. The D2-D3 segment of the large subunit-28S of ribosomal ribonucleic acid (RNA) and internal transcribed spacer (ITS) was sequenced, and phylogenetic analysis was performed. P. cecidogenus mainly occurred in the galls and to a lesser extent in the roots and soil. Nematodes were not found in leaf or inflorescence tissue. Morphological and morphometric data confirm the presence of P. cecidogenus in the stems of D. ovalifolium with gall symptoms. This study is the first to report deoxyribonucleic acid (DNA) sequences of P. cecidogenus. Based on D2-D3 and ITS partial sequences, P. cecidogenus is a sister species of the leaf-galling nematode Ditylenchus phyllobius (Sinm. Orrina phyllobia).

Global Distribution of the Reniform Nematode Genus Rotylenchulus with the Synonymy of Rotylenchulus macrosoma with Rotylenchulus borealis

Reniform nematodes of the genus Rotylenchulus are semi-endoparasites of numerous herbaceous and woody plant roots that occur largely in regions with temperate, subtropical, and tropical climates. In this study, we compared 12 populations of Rotylenchulusborealis and 16 populations of Rotylenchulusmacrosoma, including paratypes deposited in nematode collections, confirming that morphological characters between both nematode species do not support their separation. In addition, analysis of molecular markers using nuclear ribosomal DNA (28S, ITS1) and mitochondrial DNA (coxI) genes, as well as phylogenetic approaches, confirmed the synonymy of R. macrosoma with R. borealis. This study also demonstrated that R. borealis (= macrosoma) from Israel has two distinct rRNA gene types in the genome, specifically the two types of D2-D3 (A and B). We provide a global geographical distribution of the genus Rotylenchulus. The two major pathogenic species (Rotylenchulusreniformis and Rotylenchulusparvus) showed their close relationship with warmer areas with high annual mean temperature, maximum temperature of the warmest month, and minimum temperature of the coldest month. The present study confirms the extraordinary morphological and molecular diversity of R. borealis in Europe, Africa, and the Middle East and comprises a paradigmatic example of remarkable flexibility of ecological requirements within reniform nematodes.