Movement of coat protein genes from a commercial virus-resistant transgenic squash into a wild relative

Abstract

We monitored pollen-mediated transgene dissemination from commercial transgenic squash CZW-3 into its wild relative Cucurbita pepo ssp. ovifera var. texana (C. texana). Transgenic squash CZW-3 expresses the neomycin phosphotransferase II (nptII) gene and the coat protein (CP) genes of Cucumber mosaic virus (CMV), Zucchini yellow mosaic virus (ZYMV), and Watermelon mosaic virus (WMV); thereby, it is resistant to these three aphid-borne viruses. The rate of NPT II and CP transgene introgression increased with overlapping flowering patterns and a high ratio of transgenic F1 hybrids (C. texana × CZW-3) to C. texana. Transgene transfer also readily occurred from transgenic F1 hybrids into C. texana over three generations in field settings where test plants grew sympatrically and viruses were not severely limiting the growth, and fruit and seed production of C. texana. In contrast, introgression of the transgenes into C. texana was not sustained under conditions of high viral disease pressure. As expected, C. texana progeny that acquired the CP transgenes exhibited resistance to CMV, ZYMV, and WMV. This is the first report on transgene dissemination from a transgenic crop that exhibits disease resistance and hybridizes with a wild plant species without loss of fertility.

Risk assessment of genetically engineered crops: fitness effects of virus‐resistance transgenes in wild Cucurbita pepo

“…In addition, we found that conventionally bred resistance or tolerance also has the potential to impact wild C. pepo populations when exposed to viral infection. These results build upon and extend those reported in previous studies (Spencer 2001, Spencer and Snow 2001, Fuchs et al 2004a.…”

“…Fecundity increased in the following two backcross generations (Spencer 2001). Fuchs et al (2004a) showed that gene movement from cultivated C. pepo into wild populations is less likely when wild C. pepo populations are under high virus pressure; however, given the absence of the three viruses in wild C. pepo in some years (APHIS/ USDA 1994, Quemada et al 2002, Laughlin 2006, high virus pressure would not be common enough to fully prevent transgene movement into wild C. pepo in the long term. Fuchs et al (2004b) demonstrated that when multiple virus species spread via naturally occurring aphid vectors across a population of CZW-3, wild C. pepo, and the F1, BC1 and BC2 generations, transgenic backcrosses had higher reproductive output than wild C. pepo.…”

Gene Transfer and Cauliflower Mosaic Virus Promoter 35S Activity in Mammalian Cells

“…[1] A major issue associated with the production and consumption of transgenic crops is related to gene transfer and its possible consequences for human health and environment. [2,3] The present report takes place in a puzzling picture of contrasting published data. [4,5] With no claim to exhaustiveness, the experimental approach focuses on both gene transfer from food to animal tissues and evaluation of transcriptional activity of the cauliflower mosaic virus 35S (CaMV35S) promoter in mammalian cells.…”

A wild origin of the loss‐of‐function lycopene beta cyclase (CYC‐b) allele in cultivated, red‐fleshed papaya (Carica papaya)

“…Transgenic papaya has been developed to resist PRSV (papaya ringspot virus; Gonsalves, 1998 ), a major pathogen of the crop. Transgene movement in virus-resistant transgenic plants including squash and sugar beets has been reported in experimental fi eld settings ( Bartsch et al, 1996 ;Fuchs et al, 2004 ). If wild relatives acquire antivirus transgenes through gene fl ow from those virus-resistant crops, they will exhibit increased fi tness when there is selective advantage for those resisting the corresponding virus ( Snow and Palma, 1997 ;Stewart et al, 2003 ;Ellstrand et al, 2013 ).…”