Rev 12/16/2024
Chromadorea Rhabditida Tylenchina Tylenchoidea Meloidogynidae Meloidogyninae
Meloidogyne graminicola Golden & Birchfield, 1965
Rice root-knot nematode
Synonyms:
Review general characteristics of the genus Meloidogyne.
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
Important pest of rice worldwide. In India it is distributed throughout the Indo-Gangetic plains. Well-adapted to flooded conditions such as paddy rice.
C-rated pest in California. Yield losses in rainfed lowland rice in India are significant with losses up to 72% reported in sandy loam soils.
In irrigated rice it becomes established in the plant roots before transplanting,
Sedentary endoparasite.
Feeding site establishment and development typical of genus.
Type Host: Barnyard grass (Echinochloa colona).
First reported on grasses, then found on rice in Thailand, Bangladesh, India, and Laos. Also in Brazil.
Nearly all varieties of rice are susceptible.
Two pathotypes of M. graminicola have been recognized: one that can reproduce of rice culktivar BR11 and the other that cannot reproduce on BR11. There are other diffences in host range for populations from different regions (Subbotin et al., 2021).
Ecophysiological Parameters:
Haploid chromosome number n=18; reproduction is by facultative meiotic parthenogenesis. The egg nucleus undergoes a meiotic reduction division; one member of each pair of chromatids remains in a haploid nucleus and the other in a polar body. If fertilization by a male sperm occurs, the diploid number of chromosomes is restored. Otherwise the somatic number of chromosomes is restored by fusion of the egg pronucleus with the polar body from the reduction division (Subbotin et al., 2021; Triantaphyllou, 1985).
The life cycle is very short for a root-knot nematode (15-19 days at 27-37 C ) (Cabasan et al., 2013; Nguyen et al., 2914).
Migration of second-stage juveniles towards roots was similar in susceptible and resistant rice cultivars indicating equal attractiveness of the roots. However, the rates of penetration of roots and development were lower in resistant than in susceptible cultivars. There were fewer galls, females, eggs per g root and eggs per female in the resistanmt than susceptible cultivars (Cabasan et al., 2012).
Causes galling of rice roots; a single plant may have up to 1,700 galls without showing signs of obvious stress. Because of the very short life cycle (15-19 days at 27-37 C ) (Cabasan et al., 2013; Nguyen et al., 2914) a few juveniles at planting can multiply into a huge nematode population within a single crop season.
The galls formed by rice root-knot nematode are typically hooked-shaped and at the root tip. The infected plants exhibitsevere growth reduction, stunting, wilting, chlorosis, reduced tillering and unfilled spikelets and poor yield.
With high infestations (12,000/v), leaves of rice seedlings become discolored and wilt. Subsequent yield is poor.
Of 100 rice varieties tested, one was resistant and 11 were tolerant to infestation by M. graminicola.
Onion is also damaged by M. graminicola, especially when grown in rotation with rice as in the Philippines (Gergon et al., 2002).
‘Yellow Granex 429’ onion with underdeveloped bulbs and short, galled roots after inoculationwith root-knot nematode, Meloidogyne graminicola. From Gergon et al., 2002.
Infestation is greatly reduced in flooded fields, but can be high in irrigated soils.
In general, use of nematicides is too costly on a field-wide basis, although nematicides can be useful in seedbeds.
Host Plant Resistance, Non-hosts and Crop Rotation alternatives:
Resistance in rice cultivars is expressed in lower rates of penetration, development and fecundity (Cabasan et al., 2012)
Cabasan, M., Kumar, A. & De Waele, D. 2012. Comparison of migration, penetration, development and reproduction of Meloidogyne graminicola on susceptible and resistant rice genotypes. Nematology 14:405-415
Cabasan M. T. N., Kumar A., Bellafiore S. and DeWaele D. 2013. Histopathology of the rice root-knotnematode, Meloidogyne graminicola, on Oryza sativa and O. glaberrima Nematol.,16:73-81
Gergon, E. B., Miller, S. A., Halbrendt, J. M., and Davide, R. G. 2002. Effect of rice root-knot nematode on growth and yield of Yellow Granex onion. Plant Dis. 86:1339-1344.
Nguyen P. V., Bellafiore S., Petitot A., Haidar R., Bak A., Abed A., Gantet P., Mezzalira I., Engler J. and Fernandez D. 2014. Meloidogyne incognita - rice (Oryza sativa) interaction: a new model system to study plant-root-knot nematode interactions in monocotyledons. Rice 7:23
Subbotin, S.A. Palomares-Rius, J.E., Castillo, P. 2021. Systematics of Root-knot Nematodes (Nematoda: Meloidogynidae). Nematology Monographs and Perspectives Vol 14: D.J. Hunt and R.N. Perry (eds) Brill, Leiden, The Netherlands 857p.
Triantaphyllou, A.C. 1985. Gametogenesis and the chromosomes of Meloidogune nataliei: not typical of other root-knot nematodes. J. Nematology 17:1-5.
Triantaphyllou, A.C. 1985. Cytogenetics, cytotaxonomy and phylogeny of root-knot nematodes. In Sasser, J.N. & Carter, C.C. (eds) An Advanced Treatiswe on Meloidogyne.Vol 1. Biology and Control.N.C. State Universty Graphics, Raleigh, N.C. USA.
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