First Report of Carrot Cyst Nematode Heterodera carotae in Mexico: Morphological, Molecular Characterization, and Host Range Study

Abstract

During 2008 to 2016 in several nematological surveys in the Tepeaca Valley, Puebla, Mexico, carrot cyst nematode, Heterodera carotae was found parasitizing carrots, Daucus carota. The nematode was present in 61% of the sampled fields with high population densities, causing severe carrot yield losses in the Tepeaca Valley. The aim of this work was to study morphology, morphometrics, host range, and molecular characterization of the nematode. The morphological and morphometric characterization was made using light and scanning electron microscopy of the second stage juveniles, females, males and cysts, and the host range study, was performed with nine different plants from five families. The molecular identification was made by sequencing and analysing the ITS rRNA and partial COI genes. It was shown that using presently available molecular tools it is not possible to make an accurate differentiation of H. carotae from H. cruciferae. The host range test allowed to distinguish these species from each other. Our study showed that male stylet length is longer for H. carotae compared with that for H. cruciferae. This is an example of importance of combination of several methods for the correct identification of cyst nematodes. To our knowledge, this is the first report of H. carotae in Mexico.

Description of Heterodera microulae sp. n. (Nematoda: Heteroderinae) from China – a new cyst nematode in the Goettingiana group

“…n. Moreover, the nucleotide differences of these sequences with our new species sequences are also very low (2-4-bp difference for ITS and 0-1 bp for 28S). Previously, Escobar-Avila et al (2018) indicated that the sequences of H. goettingiana (HM370423 and HM370425) from Qinghai, China, might be a case of misidentification. Based on our phylogenetic and sequence analysis results, we regard Heterodera sp.…”

Evidence of strong gene flow among French populations of the carrot cyst nematode Heterodera carotae

“…Heterodera carotae is morphologically and genetically very close to the cabbage cyst nematode H. cruciferae , and the correct diagnosis is difficult and time consuming. rRNA and mitochondrial molecular markers such as ITS, cytochrome c oxidase 1 subunit ( coxI ) region (Vovlas et al , ; Escobar‐Avila et al , ) and coxI ‐derived primer sets (Madani et al , ) can help in the identification of members of the Goettingiana group, but none are able to provide an unequivocal distinction between H. carotae and H. cruciferae . As a result, only a host range test using carrot can distinguish these two species accurately (Escobar‐Avila et al , ).…”

“…rRNA and mitochondrial molecular markers such as ITS, cytochrome c oxidase 1 subunit ( coxI ) region (Vovlas et al , ; Escobar‐Avila et al , ) and coxI ‐derived primer sets (Madani et al , ) can help in the identification of members of the Goettingiana group, but none are able to provide an unequivocal distinction between H. carotae and H. cruciferae . As a result, only a host range test using carrot can distinguish these two species accurately (Escobar‐Avila et al , ). The microsatellite markers used in the present study successfully amplified both H. carotae and H. cruciferae , and the high degree of genetic differentiation observed between reference H. carotae populations and reference H. cruciferae populations allowed H. carotae and H. cruciferae individuals to be clearly distinguished in the dataset.…”

“…As a result, infestations in the field correspond to irregular areas of stunted plants, characterized by small, abnormally developed and unmarketable carrots. Heterodera carotae is present in most carrot‐growing regions worldwide: in the state of Michigan in the USA (Berney & Bird, ), in the province of Ontario in Canada (Yu et al , ), in an important Mexican carrot‐producing area (Escobar‐Avila et al , ), in 16 European countries including France (Osborne, ; Mugniery & Bossis, ; Gautier et al , ) and in South Africa (Subbotin et al , ). The range of estimated carrot crop losses related to H. carotae were estimated to be 20% to 90% in Italy (Greco et al , ) and more than 35% in Ontario (Yu et al , ).…”

Population dynamics of the carrot cyst nematode Heterodera carotae under greenhouse conditions

“…Como ocurre con todos los cultivos, la zanahoria es afectada por un gran número de patógenos, donde destacan, bacterias, hongos, virus, fitoplasmas y nematodos (Davis y Nuñez, 2007;Seo et al, 2015;Groves et al, 2020). El nematodo del quiste de la zanahoria (NQZ), Heterodera carotae Jones (1950a), es un patógeno que se encuentra distribuido en las zonas productoras de zanahoria en Europa, Norteamérica y África del Sur (Subbotin et al, 2010;Yu et al, 2017;Escobar-Avila et al, 2018;Handoo y Subbotin, 2018). Este NFQ tiene un rango limitado de hospedantes: zanahorias silvestres y cultivadas, y algunos miembros silvestres de la familia Apiaceae, como Torilis spp.…”