Further observations on Meloidogyne enterolobii (Nematoda: Meloidogynidae) infecting guava (Psidium guajava) in India

Abstract

Root-knot nematodes ( Meloidogyne spp.) infect a large number of crops including guava. We investigated a population of Meloidogyne sp. infecting guava in the Coimbatore region of Tamil Nadu, India for identification and species confirmation. Detailed morphological and morphometric observations based on second-stage juveniles, males, females, and perineal patterns showed resemblance of the isolated population with the original and subsequent descriptions of M. enterolobii . Isozyme analysis of the young egg-laying females displayed the characteristic esterase phenotype pattern similar to that of M. enterolobii. Additionally, the identity of the nematode population was further validated by M. enterolobii specific SCAR marker and ITS rDNA. Recently published reports on the occurrence and morphological descriptions of M. enterolobii from India are largely incongruent with the original and subsequent redescriptions of the species. Here, we present the most comprehensive morphology and morphometrics of an Indian population of M. enterolobii for its authentic identification.

Molecular phylogeny and morphological studies reveal a 30‐year‐old rain tree (Samanea saman) maintains populations of Meloidogyne enterolobii, a new host plant in Thailand

“…According to Latif et al (2014), rain tree bark greatly inhibits the egg hatching of M. incognita because it contains alkaloids, glycosides and terpenes that exhibit antibacterial, antifungal, insecticidal and nematicidal activities. In this study, the perineal patterns of M. enterolobii were oval-shaped and with moderate-high, squarish dorsal arch, and a weak lateral line, consistent with previous observations (Ghule et al, 2021). In addition, the morphometrics of the M. enterolobii collected from the rain tree were more closely related to the original population (Yang & Eisenback, 1983) but not significantly different from those in other reports (Brito et al, 2004) because all the morphometric parameter ranges from the rain tree population overlapped with those in other populations.…”

“…Morong) in China (Yang & Eisenback, 1983). It has been synonymized with M. mayaguaensis Rammah & Hirschmann, 1988 identified from eggplant ( Solanum melogena L.) in Puerto Rico (Ghule et al, 2021; Rammah & Hirschmann, 1988) because they provide the same esterase phenotype and mitochondrial DNA sequence (Karssen et al, 2012; Xu et al, 2004). Since M. enterolobii can overcome resistance genes, such as Mi‐1 in tomato ( Solanum lycopersion L.), Mh in potato ( Solanum tuberosum L.), Mir1 in soybean ( Glycine max (L.) Merr), N in bell pepper ( Capsicum annuum L .…”

“…Species of RKN are usually identified using biochemical and molecular techniques to confirm the results of morphological techniques, such as perineal patterns. Species identification based on morphological characteristics is often inaccurate due to the similar morphologies among RKN, such as those between M. luci Carneiro et al, 2014 and M. ethiopica Whitehead, 1968 (Maleita et al, 2021) or M. enterolobii and M. incognita (Ghule et al, 2021; Moore et al, 2020). Morphological techniques also require specialized expertise (Maleita et al, 2021).…”

“…Tabasco in sweet pepper (Capsicum annuum L.), and Rk in cowpea (Vigna unguiculata L.) (Castagnone-Sereno, 2012), the European and Mediterranean Plant Protection Organization (EPPO) has placed it on the A-2 list in 2010, defining it as an aggressive quarantined pest (Collett et al, 2021). Meloidogyne enterolobii has been previously identified in other locations, such as ibid guava (Psidium guajava L.), euphorbia (Euphorbia antiquorum L.) and cotton (Gossypium hirsutum L.) in Florida, India and Brazil (Brito et al, 2004;Galbieri et al, 2020;Ghule et al, 2021). The distribution of M. enterolobii has been reported in Southeast Asia, notably in Singapore, Vietnam, and Thailand; for example, 121 host plants from Thailand have been recorded in the EPPO (EPPO, 2021;Tigano et al, 2010).…”

Characterization of Meloidogyne enterolobii intercepted from baobab (Adansonia digitata L.) seedlings from Thailand during Japanese import plant quarantine inspection

“…The morphology and morphometrics of the RKN population intercepted from baobab from Thailand were similar to those of the original description of M. enterolobii from China (Yang & Eisenback, 1983) and were also within the ranges reported for M. enterolobii populations from India (Ghule et al, 2020), Puerto Rico (Rammah & Hirschmann, 1988), South Africa (Rashidifard et al, 2019), USA (Brito et al, 2004) and Vietnam (Trinh et al, 2022). The sequences of D2-D3 of 28S rRNA, COII-16S rRNA and COI genes obtained in this study matched well (99 -100 % similarity) with each of the M. enterolobii gene sequences deposited in Gen-Bank.…”