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Master's Research

Analysis of the control region of the mitochondrial genome of the Indian brown planthopper (BPH, Nilaparvata lugens) populations
Student Name : Ms Rashi Anand
Guide : Dr Ramakrishnan Sitaraman
Status : Completed
Year : 2017
Host Organization : ICGEB, New Delhi
Supervisor (Host Organisation) : Dr Suresh Nair

Abstract

The brown planthopper (BPH; Nilaparvata lugens) is the most destructive pest of paddy in India. BPH is capable of traversing large distances and therefore, widely distributed and cause massive crop loss. In order to devise effective control mechanisms, it is necessary to understand the variability and identity of the insect population prevalent in an area. In this study, we show that the repeats present in the control region (CR) of the mitogenome of the BPH are capable of broadly differentiating the populations of BPH. The CR of 5 individuals each, from 5 different BPH populations (Delhi, Punjab, Hyderabad, Warangal and Nalgonda) from India, were PCR amplified, using two different primer pairs, as two overlapping fragments (~800 bp and ~1500 bp). These fragments were cloned and sequenced. Using bioinformatics tools, the complete contig of the CR was constructed and the iterations of a 21-bp repeat motif in the CR was evaluated in each of BPH individuals screened. Frequency and distribution of nucleotides at specific regions of the CR were also evaluated. Comparison of the CR sequences of the Indian BPH individuals with that of the Chinese population revealed differences in the number of iterations of the 21-bp repeat motif and nucleotide variations at other regions. The number of iterations of the 21-bp repeat was by far more in the Chinese population than all CR reported in this study. Phylogenetic analysis placed all the individuals representing the South Indian populations under one clade. This study has identified a potentially useful genetic marker capable of differentiating BPH populations. However, this needs to be confirmed using a larger sampling. Successful development of such markers, capable of rapidly identifying different populations of BPH, will be invaluable for developing Integrated Pest Management (IPM) strategies for the effective management of such an economically important pest of rice.

Keywords: Mitogenome, control region, biotypes, polymorphism, phylogeny.
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