ACQUISITION AND TRANSMISSION OF AGROBACTERIUM BY THE WHITEFLY BEMISIA-TABACI

Whiteflies transmit many different plant pathogens. We show here that the whitefly Bemisia tabaci can also acquire Agrobacterium tumefaciens from liquid cultures and from crown galls, and transmit it to plants. Cloned tomato yellow leaf curl virus (TYLCV) DNA and A. tumefaciens t umor-inducing functions were used as reporter genes. Whiteflies were f ed through membranes on cultures of Agrobacterium At::pTY4 containing a dimeric copy of an infectious TYLCV genomic clone between the T-DNA borders of a binary vector. One hour of feeding was sufficient for the insects to be able to transmit TYLCV to tomato test plants. Infectiou s Agrobacterium was recovered from whiteflies that fed on At::pTY4 cul tures, indicating that bacteria was acquired and remained intact in th e insects. Whiteflies also acquired the virulent A. tumefaciens strain C58 from crown galls and induced tumors in tomato test plants. PCR an d Southern blot analyses indicated that the target plant tissues were transformed. These results show that an insect can transfer foreign ge nes to plants by acquiring and delivering transforming bacteria.