Polymorphisms flanking the mariner integration sites in the rice gall midge (Orseolia oryzae Wood-Mason) genome are biotype-specific.
In an effort to study genome diversity within and between the Indian biotypes of the Asian rice gall midge, Orseolia oryzae, a major insect pest of rice, we made use of mariner transposable element integration site polymorphisms. Using degenerate primers, the design of which is based on mariner sequences, we amplified a ca. 450 bp mariner sequence from the rice gall midge. The mariner sequence showed homology with that of a mariner element isolated from the Hessian fly, Mayetiola destructor, a major dipteran pest of wheat. Southern hybridization, using this mariner fragment as a probe, revealed that the mariner elements are moderately to highly repetitive in the rice gall midge genome. Based on the sequence information of this 450-bp PCR-amplified fragment, outward-directed primers were designed and used in an inverse PCR (iPCR) to amplify the DNA flanking the conserved regions. To study the regions flanking the mariner integration sites, we employed a novel PCR-based approach: a combination of sequence specific amplification polymorphism (SSAP) and amplified fragment length polymorphism (AFLP). The outward-directed mariner-specific primer was used in combination with adapter-specific primers with 1-3 selective nucleotides at their 3' ends. The amplification products were resolved on an agarose gel, Southern-transferred onto nylon membranes, and probed with the iPCR fragment. Results revealed biotype-specific polymorphisms in the regions flanking the mariner integration sites, suggesting that mariner elements in the rice gall midge may be fixed in a biotype-specific manner. The implications of these results are discussed in the context of biotype differentiation.
Behura
S K
SK
International Centre for Genetic Engineering and Biotechnology, New Delhi, India.
Nair
S
S
Mohan
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002683:Chironomidae / Q000235:genetics*; D004251:DNA Transposable Elements / Q000235:genetics*; D016678:Genome; D008969:Molecular Sequence Data; D012275:Oryza / Q000469:parasitology*; D011110:Polymorphism, Genetic
D004251:DNA Transposable Elements