[Novel DNA-beta associated molecules produced by sequence recombination and deletion of cotton leaf curl Multan virus...

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.

We purified total DNA from cotton and okra plants exhibiting leaf curl symptoms; PCR amplified and sequenced CLCuMV satellite DNA (DNAbeta) -related small DNA molecules.

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 DNAbeta 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 DNAbeta. Common nucleotides were found around the junction points of DNA-A and DNAbeta 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 DNAbeta were conserved on the recombination process. The 754 nt molecule was produced by deletion of CLCuMV DNAbeta in the C1 open reading frame and A-rich region.

We identified a novel recombinant molecule originated from CLCuMV DNA-A and DNAbeta and a small defective molecule of DNAbeta. 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.