Genetic diversity of the root-knot nematode Meloidogyne graminicola in
rice (Oryzasativa L.) based on mitochondrial COI gene
Abstract
The root-knot nematode Meloidogyne graminicola is an important parasitic
nematode that causes huge economic losses to rice production in China.
In the present study, 54 M. graminicola populations were collected from
the major rice-growing areas of ten provinces in China. The cytochrome
oxidase subunit I (COI) gene sequence of M. graminicola populations in
the studied locations were PCR-amplified, sequenced, and evaluated for
genetic diversity analysis. The total number of mutations, haplotypes
(Hap) numbers, the average number of nucleotide differences (k),
haplotype diversity (Hd), and nucleotide diversity (π) of mtCOI gene
were 39, 15, 5.37, 0.646, and 0.00682, respectively. The significant
differences in Fst value (0.593) and a low level of gene flow (0.333)
were detected between the 54 M. graminicola populations. High genetic
diversity was observed within each population and a small genetic
distance was found between them. The phylogenetic analyses showed that
54 M. graminicola populations were divided into three large groups
corresponding to the Central Region (CR), Southern China (SC) and the
Yangtze Valley (YV). Hap8 was the most widely distributed and was
considered to be an origin of haplotype, revealing a separate
evolutionary origin in China. The high genetic differentiation of M.
graminicola populations was result of variation within each of the
defined geographical groups, according to an analysis of molecular
variance. No significant relationship was observed between the genetic
distance and geographical distance in M. graminicola populations. To the
best of our knowledge, this is the first study conductedon the genetic
diversity of M. graminicola infesting rice in China and provides a
theoretical basis for the future management of the M. graminicola
population and potential approach for increasing production of rice.