Genetic diversity and differentiation of populations of Chlorops oryzae (Diptera, Chloropidae)

Ailin Zhou,Xinwen Li,Youzhi Li,Xiaoping Tan,Zhongcai Li,Wenbing Ding,Ping Tian,Lin Qiu,Zhengbing Zhang,Hualiang He

doi:10.1186/s12898-020-00293-8

Abstract

BackgroundChlorops oryzae is an important pest of rice crops. There have been frequent outbreaks of this pest in recent years and it has become the main rice pest in some regions. To elucidate the molecular mechanism of frequent C. oryzae outbreaks, we estimated the genetic diversity and genetic differentiation of 20 geographical populations based on a dataset of ISSR markers and COI sequences.ResultsISSR data revealed a high level of genetic diversity among the 20 populations as measured by Shannon’s information index (I), Nei’s gene diversity (H), and the percentage of polymorphic bands (PPB). The mean coefficient of gene differentiation (Gst) was 0.0997, which indicates that only 9.97% genetic variation is between populations. The estimated gene flow (Nm) value was 4.5165, indicating a high level of gene flow and low, or medium, genetic differentiation among some populations. The results of a Mantel test revealed no significant correlation between genetic and geographic distance among populations, which means there is no evidence of significant genetic isolation by distance. An UPGMA (unweighted pair-group method with arithmetic averages) dendrogram based on genetic identity, did not indicate any major geographic structure for the 20 populations examined. mtDNA COI data indicates low nucleotide (0.0007) and haplotype diversity (0.36) in all populations. Fst values suggest that the 20 populations have low, or medium, levels of genetic differentiation. And the topology of a Neighbor-Joining tree suggests that there are no independent groups among the populations examined.ConclusionsOur results suggest that C. oryzae populations have high genetic diversity at the species level. There is evidence of frequent gene flow and low, or medium, levels of genetic differentiation among some populations. There is no significant correlation between genetic and geographic distance among C. oryzae populations, and therefore no significant isolation by distance. All results are consistent with frequent gene exchange between populations, which could increase the genetic diversity, and hence, adaptability of C. oryzae, thereby promoting frequent outbreaks of this pest. Such knowledge may provide a scientific basis for predicting future outbreaks.

Highlights

Chlorops oryzae is an important pest of rice crops
Cytochrome Oxidase I (COI) gene analysis Genetic diversity and differentiation In total, 432 individuals collected from different locations were used to amplify 684 bp of the COI gene sequence, which defined 47 haplotypes
The estimated Gene flow (Nm) value was 4.5165 (Table 6). These results suggest that genetic differentiation among populations of C. oryzae is impeded by high gene flow

Summary

Introduction

Chlorops oryzae is an important pest of rice crops. There have been frequent outbreaks of this pest in recent years and it has become the main rice pest in some regions. Chlorops oryzae (Diptera, Chloropidae) is an important pest of paddy rice plants, which inflicts significant economic damage to rice crops throughout Asia. Frequent C. oryzae outbreaks in recent years have caused the species to become a major pest in some regions. The propensity for outbreaks may itself play an important role in homogenizing genetic variation and intensifying gene flow between pest populations [5, 6]. The frequent outbreaks of C. oryzae are associated with the species’ genetic diversity, population demography and high rate of gene flow between populations

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