Title: ENGINEERING RESISTANCE AGAINST PAPAYA RINGSPOT VIRUS BY NATIVE, CHIMERIC AND SYNTHETIC TRANSGENES
Fermin, G - UNIVERSITY OF LOS ANDES
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: July 24, 2003
Publication Date: March 20, 2004
Citation: Fermin, G., Gonsalves, D. 2004. Engineering resistance against papaya ringspot virus by native, chimeric and synthetic transgenes. In: G Lebenstein and G. Thottappilly, editors. Virus and virus-like diseases of major crops in developing countries. The Netherlands: Kluwer Academic Press Publishers. Chapter 20:P 497-518.
The transgenic Rainbow papaya is hemizygous for the coat protein gene of a papaya ringspot virus (PRSV) isolate from Hawaii. Rainbow shows excellent resistance to PRSV isolates in Hawaii, but is susceptible to PRSV isolates from many parts of the world. In order to obtain transgenic papaya which might be resistant to strains throughout the world, we developed two types of transgenes. The first ‘segmented’ transgene consist of three linked coat protein segments (about 200 nucleotides long) from strains of PRSV from Hawaii, Thailand, and Taiwan. The second ‘synthetic’ transgene consist of two 200 nucleotide segments whose sequences were derived by comparing coat protein gene sequences of PRSV isolates from throughout the world. These sequences were configured to get the highest homology to any of the PRSV isolates. The segmented gene constructs were transformed into papaya and resulting plants showed resistance to multiple strains PRSV in initial experiments. The synthetic gene approach was validated with the tospoviruses, and papaya have been transformed with the synthetic genes. These two approaches could have significant impact in developing transgenic papaya with resistance to a wide range of PRSV strains. Thus, it is possible that only one or a few transgene constructs would impart resistance to many PRSV strains. This simple approach would be especially valuable for developing countries.