Field testing, gene flow assessment and pre-commercial studies on transgenic Solanum tuberosum spp. tuberosum (cv. Spunta) selected for PVY resistance in Argentina

Abstract

Solanum tuberosum ssp. tuberosum (cv. Spunta) was transformed with a chimeric transgene containing the Potato virus Y (PVY) coat protein (CP) sequence. Screening for PVY resistance under greenhouse conditions yielded over 100 independent candidate lines. Successive field testing of selected lines allowed the identification of two genetically stable PVY-resistant lines, SY230 and SY233, which were further evaluated in field trials at different potato-producing regions in Argentina. In total, more than 2,000 individuals from each line were tested along a 6-year period. While no or negligible PVY infection was observed in the transgenic lines, infection rates of control plants were consistently high and reached levels of up to 70-80%. Parallel field studies were performed in virus-free environments to assess the agronomical performance of the selected lines. Tubers collected from these assays exhibited agronomical traits and biochemical compositions indistinguishable from those of the non-transformed Spunta cultivar. In addition, an interspecific out-crossing trial to determine the magnitude of possible natural gene flow between transgenic line SY233 and its wild relative Solanum chacoense was performed. This trial yielded negative results, suggesting an extremely low probability for such an event to occur.

Potato virus Y: a major crop pathogen that has provided major insights into the evolution of viral pathogenicity

“…Most recently, potato plants transformed with a chimeric transgene containing PVY CP sequences have been evaluated in the field for a period of 6 years in Argentina. The plants showed null or negligible infection and preserved their agronomical traits and biochemical characteristics (Bravo‐Almonacid et al ., ).…”

Crop immunity against viruses: outcomes and future challenges

“…These observations led to a plethora of RNAi-mediated engineered resistances, using virus-derived double-stranded, hairpin RNAs, or artificial miRNAs (e.g., Qu et al, 2007 ; Hashmi et al, 2011 ; Shimizu et al, 2011 ; Yadav et al, 2011 ; Zhang et al, 2011a , b ; Lin et al, 2012 ; Shekhawat et al, 2012 ; Lemgo et al, 2013 ; Odipio et al, 2013 ; Zhao and Song, 2014 ). In the cases where virus-resistant GM varieties have been deployed and/or commercialized (including transgenic squash, papaya, plum, potato, and bean), this strategy has so far proven to be remarkably efficient ( Tricoli et al, 1995 ; Lius et al, 1997 ; Ferreira et al, 2002 ; Malinowski et al, 2006 ; Zagrai et al, 2008 ; Bravo-Almonacid et al, 2012 ; Aragão et al, 2013 ). In spite of engineering resistance success (especially RNAi-based resistant crops), public concerns over the potential ecological impact of GM crops and GM organisms overall have so far significantly limited their use, in particular in Europe.…”

Polyploidy and Plant Breeding

“…This failure shows that consumer acceptance is key for adopting transgenic potatoes. There are promising transgenic tetraploid potatoes showing, among others, broad-spectrum resistance to late blight (Song 2003;Kuhl et al 2007;Halterman et al 2008), host plant resistance to potato tuber moth (Douches et al 2004) and Potato virus Y (Bravo-Almonacid et al 2012) or high carotenoid (Ducreux et al 2005) and protein (Chakraborty et al 2010). A cisgenic approach was also used to introduce into potato cultigens broad-spectrum late blight resistance genes Rpi-sto1 and Rpi-vnt1.1 from the crossable species S. stoloniferum and S. venturii (Jo et al 2014).…”