Plant Insect Interaction

PLANT BIOLOGY AND BIOTECHNOLOGY / Biotic and Abiotic Stress

Research Interests

Biotic stress, insect-plant interaction, gene expression, crop improvement, abiotic stress.

Description of Research

The Group is interested in understanding insect-plant interaction. The Asian rice gall midge (Orseolia oryzae; Order Diptera, Family Cecidomyiidae) is an important insect pest of rice and is responsible for causing considerable yield and monetary loss to farmers in India, Africa, South East Asia and neighbouring countries. Another reason that gall midge is such a serious pest is the existence of many biotypes that are able to overcome the deployed resistance genes in rice. In most cases, a single dominant gene governs resistance. Four of these gall midge resistance genes (Gm2, Gm4, Gm7 and Gm8) have been mapped and tagged by us. A PCR-based marker aided selection (MAS) system for these genes was first developed in our lab.

In the case of the rice gall midge, it is currently believed, that the initial interaction between the midge and the host determines whether the latter would succumb to the midge or is able to resist it. During the infestation process and subsequent feeding on the host, the larvae inject substance(s) into the host. As in the case of pathogenic bacteria and fungi, these products could be determinants of the avirulence/virulence phenomenon. Extending this idea further, the genes that encode these molecules could be determinants of gall midge biotypes. Further, the genes that encode such molecules could be those that encode secreted salivary gland proteins (SSGPs), which in turn could be determinants of gall midge virulence/avirulence. Therefore, characterizing genes that encode SSGPs could provide us a handle to study this interaction and also gain valuable insight into the process of infestation of rice by this pest.

We have, for the first time, successfully PCR amplified regions of SSGPs of the rice gall midge. Studies are currently underway to understand the role of these SSGPs in the rice-pest interaction. The amplified regions include different families of the rice gall midge SSGPs. We have analyzed the expression patterns of some of the different SSGPs in larvae interacting with susceptible (SH; incompatible interaction) or resistant host (RH; compatible interaction). Our results indicate some of the SSGPs overexpress when interacting with SH while others overexpress when feeding on RH. Furthermore, we also show that some of the SSPGs can influence the host physiology. We have also carried out pyrosequencing-based transcriptome analysis of the Asian rice gall midge and our results reveal differential response of the gall midge depending on whether it is in a compatible or incompatible interaction with its host. In addition, using suppressive subtraction hybridization (SSH) cDNA libraries and microarray analysis, we show differential response of gall midge-resistant and -susceptible rice plants genes to gall midge attack. Further, we will be studying the role of miRNAs in the interaction and also carry out a metabolomics analyses to understand the rice-gall midge interaction in particular and insect-plant interaction in general.

The Group has recently investigated the role of transposable elements (TEs) in conferring genetic plasticity that probably facilitates rapid adaptations in the brown planthopper (BPH), a major pest of rice. In addition, the group has identified methylation patterns involved in modulating TE dynamics in BPH under stress (Gupta and Nair, Genomics, 2021).

Recent Publications