Abstract

BackgroundThe Asian rice gall midge (Orseolia oryzae) is a destructive insect pest of rice. Gall midge infestation in rice triggers either compatible or incompatible interactions leading to survival or mortality of the feeding maggots, respectively. In incompatible interactions, generation of plant allelochemicals/defense molecules and/or inability of the maggots to continue feeding on the host initiate(s) apoptosis within the maggots. Unraveling these molecular events, triggered within the maggots as a response to feeding on resistant hosts, will enable us to obtain a better understanding of host resistance. The present study points towards the likely involvement of a defender against apoptotic cell death gene (DAD1) in the insect in response to the host defense.ResultsThe cDNA coding for the DAD1 orthologue in the rice gall midge (OoDAD1) consisted of 339 nucleotides with one intron of 85 bp and two exons of 208 and 131 nucleotides. The deduced amino acid sequence of OoDAD1 showed a high degree of homology (94.6 %) with DAD1 orthologue from the Hessian fly (Mayetiola destructor) —a major dipteran pest of wheat. Southern hybridization analysis indicated that OoDAD1 was present as a single copy in the genomes of the Asian rice gall midge biotypes (GMB) 1, 4 and 4 M. In the interactions involving GMB4 with Jaya (susceptible rice host) the expression level of OoDAD1 in feeding maggots gradually increased to 3-fold at 96hai (hours after infestation) and peaked to 3.5-fold at 96hai when compared to that at 24 hai. In contrast, expression in maggots feeding on RP2068 (resistant host) showed a steep increase of more than 8-fold at 24hai and this level was sustained at 48, 72 and 96hai when compared with the level in maggots feeding on Jaya at 24hai. Recombinant OoDAD1, expressed in E. coli cells, when injected into rice seedlings induced a hypersensitive response (HR) in the resistant rice host, RP2068, but not in the susceptible rice variety, Jaya.ConclusionsThe results indicate that the expression of OoDAD1 is triggered in the feeding maggots probably due to the host resistance response and therefore, is likely an important molecule in the initial stages of the interaction between the midge and its rice host.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0618-y) contains supplementary material, which is available to authorized users.

Highlights

  • The Asian rice gall midge (Orseolia oryzae) is a destructive insect pest of rice

  • Characterization of Orseolia oryzae DAD1 (OoDAD1) The full-length cDNA of OoDAD1 consisted of 339 nucleotide bases [GenBank:KP890835] coding for 113 amino acids with a predicted molecular mass of 12.7 kDa

  • The current study indicated that OoDAD1 is transcriptionally modulated in the pest depending on whether it is feeding on a susceptible or resistant host

Read more

Summary

Introduction

The Asian rice gall midge (Orseolia oryzae) is a destructive insect pest of rice. Gall midge infestation in rice triggers either compatible or incompatible interactions leading to survival or mortality of the feeding maggots, respectively. Generation of plant allelochemicals/defense molecules and/or inability of the maggots to continue feeding on the host initiate(s) apoptosis within the maggots Unraveling these molecular events, triggered within the maggots as a response to feeding on resistant hosts, will enable us to obtain a better understanding of host resistance. Apoptosis or programmed cell death features stereotypical morphological changes such as shrinking of cell, cell deformation, condensation of chromatin and cell fragmentation into apoptotic bodies These changes are the consequences of several biochemical and molecular events occurring within the cell [1]. Differential regulation of DAD1 gene was observed in flower petals during the senescence phase [9] Results of these investigations indicated the important role played by DAD1 in apoptosis and development in both animal and plant systems. No reports on the role of any anti-apoptotic genes in the rice-gall midge interaction are available

Methods
Results
Discussion
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call