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Morphological and molecular analyses of a Meloidogyne mali population with high intragenomic rRNA polymorphism
Jianfeng Gu1, Yiwu Fang1, Lele Liu1
1Ningbo Customs Technical Centre (Ningbo Inspection and Quarantine Science Technology Academy), 8 Huikang Road, Ningbo, 315100, Zhejiang, P.R. China.
Abstract:
Root-knot nematode, Meloidogyne mali can cause damage in trees, shrubs, and herbaceous plants, and was placed on the EPPO Alert List in 2014. In the present study, we report a population isolated from Japanese maple. The recovered population is described by detailed morphological and molecular approaches. The molecular phylogentic analysis based on 28S rRNA, ITS, and mitochondrial COI genes places the population in the clade together with other M. mali sequences available in GenBank. The cloned sequences of the 28S rRNA gene revealed a high intragenomic rRNA polymorphism where the polymorphic copies are spread across M. mali clade. Similarly, we also found high variation in the mitochondrial COI gene. Among four haplotypes in M. mali, three occur in the newly found population. Our study provides the first report of intragenomic polymorphism in M. mali, and the results suggest that intragenomic polymorphism maybe widespread in Meloidogyne.
Insights
A new population of the damaging root-knot nematode, Meloidogyne mali, was identified in Japanese maple. This study reveals significant intragenomic polymorphism in Meloidogyne, suggesting it may be widespread in the genus.
Area of Science:
- Plant Nematology
- Molecular Phylogenetics
- Genetics
Background:
- Root-knot nematodes, particularly Meloidogyne mali, pose a significant threat to woody and herbaceous plants.
- Meloidogyne mali was added to the European and Mediterranean Plant Protection Organization (EPPO) Alert List in 2014 due to its potential economic impact.
Purpose of the Study:
- To characterize a newly identified population of Meloidogyne mali isolated from Japanese maple.
- To investigate the genetic diversity and phylogenetic placement of this M. mali population.
- To explore intragenomic polymorphism within M. mali populations.
Main Methods:
- Morphological analysis of the nematode population.
- Molecular phylogenetic analysis using 28S rRNA, ITS, and mitochondrial COI genes.
- Sequencing and analysis of cloned 28S rRNA gene copies to assess intragenomic polymorphism.
- Haplotype analysis of the mitochondrial COI gene.
Main Results:
- The isolated population was molecularly confirmed as Meloidogyne mali, clustering with existing sequences in phylogenetic analyses.
- High intragenomic polymorphism was detected in the 28S rRNA gene sequences within the M. mali clade.
- Significant variation was observed in the mitochondrial COI gene, with three out of four known haplotypes present in the new population.
Conclusions:
- This study reports the first evidence of intragenomic polymorphism in Meloidogyne mali.
- The findings suggest that intragenomic polymorphism may be a common characteristic across the Meloidogyne genus.
- Understanding this polymorphism is crucial for accurate species identification and population genetics studies of root-knot nematodes.
