Development of Genetically Engineered Resistant Papaya for <i>papaya ringspot virus</i> in a Timely Manner: A Comprehensive and Successful Approach

Abstract

Papaya orchards throughout most of the world are severely damaged by the destructive disease caused by the papaya ringspot virus (PRSV). PRSV-resistant papaya expressing the coat protein gene (CP) of PRSV have been used in Hawaii to control PRSV since 1998. This chapter presents the experimental steps involved in the development of transgenic papaya, including transgene construction, transformation, and analysis for virus resistance of the transformed papaya. We also describe the important factors that enabled deregulation, commercialization, and adoption of transgenic papaya to occur in Hawaii in a timely manner. Transfer of this technology to other countries with the similar goal and the development of transgenic papaya in other regions of the world also are described.

Plant Genetics, Sustainable Agriculture and Global Food Security

“…The transgene was designed with a premature stop codon in the PRSV coat protein sequence to prevent expression of a functional coat protein because, at the time of engineering, it was thought that the protein itself was an important factor in resistance. RNA analysis later revealed that the plants with the best resistance exhibited the least detectable message, which was suggestive of the involvement of an RNA silencing mechanism (Tripathi et al 2006).…”

“…In anticipation of disease spread, Dennis Gonsalves, a local Hawaiian, and co-workers initiated a genetic strategy to control the disease (Tripathi et al 2006). This research was spurred by an earlier observation that transgenic tobacco expressing the coat protein gene from tobacco mosaic virus showed a significant delay in disease symptoms caused by tobacco mosaic virus (Powell-Abel et al 1986).…”

“…As reviewed here, benefits include massive reductions in insecticides in the environment (Qaim and Zilberman 2003;Huang et al 2005), improved soil quality and reduced erosion (Committee on the Impact of Biotechnology on Farm-Level Economics and Sustainability and National Research Council 2010), prevention of the destruction of the Hawaiian papaya industry (Tripathi et al 2006), enhanced health benefits to farmers and families as a result of reduced exposure to harsh chemicals (Huang et al 2002(Huang et al , 2005, economic benefits to local communities (Qaim et al 2010), enhanced biodiversity of beneficial insects (Cattaneo et al 2006), reduction in the number of pest outbreaks on neighboring farms growing nongenetically engineered crops (Hutchison et al 2010), and increased profits to farmers (Tabashnik 2010). Genetically engineered crops have also dramatically increased crop yields-.30% in some farming communities (Qaim et al 2010).…”

Effects of subchronic exposure to transgenic papayas (Carica papaya L.) on liver and kidney enzymes and lipid parameters in rats

“…23 Other countries such as Jamaica, Brazil, Venezuela, Thailand, Australia, Taiwan and, recently, Bangladesh have since used the technology and the cp gene from their regions to develop their own transgenic varieties. 24 These transgenic papayas are at various stages of development and evaluation and have not yet reached the respective local markets.…”

Potyviridae

“…To face these situations, it is now possible to use bioengineering methods to introduce genes for virus resistance obtained from novel sources, including pathogen-derived. Indeed, transgenic plants of several species have been produced aiming to fight potyviruses, such as potatoes with CP-or replicase-mediated resistance to PVY, squashes with CP-mediated resistance to ZYMV and papaya with CP-mediated resistance to Papaya ringspot virus (PRSV), occasionally contributing to save a complete industry (Tripathi et al, 2007).…”