Novel DNA-β associated molecules produced by sequence recombination and deletion of cotton leaf curl Multan virus complex

Abstract:

Abstract:［Objective］ Cotton leaf curl disease (CLCuD) is a major constraint to cotton production，causing great economic losses in Pakistan and India． In China，CLCuD has been discovered in the field of Nanning，GuangXi．To better understand this disease，we sequenced the virus-associated small DNA molecules．［Methods］ We purified total DNA from cotton and okra plants exhibiting leaf curl symptoms; PCR amplified and sequenced CLCuMV satellite DNA (DNAβ)-related small DNA molecules．［Results］ We identified 2 novel recombinant DNA molecules with 1384 nucleotides in cotton and 754 nucleotides in okra． The 1384 nt molecule contains partial DNA-A and DNAβ of CLCuMV GX1． It includes the intergenic region，adjacent AV2 and AC1 coding sequences，and reverse complementary AC3 of DNA-A and A-rich region of DNAβ．Common nucleotides were found around the junction points of DNA-A and DNAβ sequences，suggesting they were the sites of recombination．Comparison with previous reported CLCuMV recombinants produced in lab showed that the intergenic region of DNA-A and A-rich region of DNAβ were conserved on the recombination process． The 754 nt molecule was produced by deletion of CLCuMV DNAβ in the C1 open reading frame and A-rich region．［Conclusion］ We identified a novel recombinant molecule originated from CLCuMV DNA-A and DNAβ and a small defective molecule of DNAβ． This is the first report of sequence recombination and deletion of CLCuMV in China，which may be helpful to understand the CLCuMV evolution and host adaptation．