Extreme resistance to two Brazilian strains of Potato virus Y (PVY) in transgenic potato, cv. Achat, expressing the PVYº coat protein

Abstract

ROMANO, E.; FERREIRA, A.T.; DUSI, A.N.; PROITE, K.; BUSO, J.A.; ÁVILA, A.C.; NISHIJIMA, M.L.; NASCIMENTO, A.S.; BRAVO-ALMONACID, F.; MENTABERRY, A.; MONTE, D.; CAMPOS, M.A.; MELO, P.E.; CATTONY, M.K. TORRES, A.C. Horticultura Brasileira, Brasília, v. 19, n. 2, junho SUMMARYThe coat protein (CP) gene of the potato virus Y strain "o" (PVY O ) was introduced into potato, cultivar Achat, via Agrobacterium tumefaciens-mediated transformation. Sixty three putative transgenic lines were challenged against the Brazilian strains PVY-OBR and PVY-NBR. An extremely resistant phenotype, against the two strains, was observed in one line, denominated 1P. No symptoms or positive ELISA results were observed in 16 challenged plants from this line. Another clone, named as 63P, showed a lower level of resistance. Southern blot analysis showed five copies of the CP gene in the extremely resistant line and at least three copies in the other resistant line. The stability of the integrated transgenes in the extreme resistant line was examined during several in vitro multiplications over a period of three years, with no modification in the Southern pattern was observed. The stability of the transgenes, the absence of primary infections and the relatively broad spectrum of resistance suggest that the extremely resistant line obtained in this work can be useful for agricultural purposes.Keywords: Solanum tuberosum, GMO. (Accepted for publication in 21 th May, 2.001) the 3' end of the viral genome and its sequence has been established for several PVY strains (Bravo-Almonacid & Mentaberry, 1989; Hay et al.,1989; Puurand et al., 1990; Robaglia et al., 1989;Thole et al., 1993;van der Vlugt et al., 1989;Wefels et al., 1989). PVY infects potato (Solanum tuberosum) causing necrosis, mottling or yellowing-vein clearing of leaflets, leaf dropping and premature death (de Bokx, 1990). In fields established with infected tuber seeds, yield reduction is dramatic (De Bokx & Piron, 1990; Brandolini et al., 1992). To avoid it, growers are compelled to a frequent renewal of tuber seed stocks, with lasting effects on production costs, growers' income, and final potato prices for consumers. PVY has been reported to infect potato in Brazil for at least 25 years (Alba & Oliveira, 1976), although its actual importance has been masked for two decades by the joint occurrence of PLRV (Câmara et al., 1986). In 1994 severe losses exclusively due to PVY were reported, mainly on fields planted with cultivar Achat (Figueira, 1999). Achat is one important potato cultivar in Brazil (Torres et al, 1999). free seed potatoes and special cultural practices (Gugerli, 1986). Usually these procedures do not offer permanent solutions to PVY infection. The development of resistant cultivars in potato can be a more effective strategy but, due to the tetraploid nature of its genome, potato breeding is known to be extremely difficult. However the ability to transform plants using Agrobacterium tumefaciens Ti plasmids has made it possible to produce plants with new traits wi...

A direct organogenesis protocol from shoot segments of Solanum tuberosum cv. Monalisa

“…New knowledge acquired after complete potato genome sequencing (TPGSC, 2011) opened a range of possibilities to genetic manipulation, specially through genetic transformation due to the high potato susceptibility to Agrobacterium tumefaciens infection (Vayda and Belknap, 1992). Recombinant DNA technology and plant regeneration from tissue culture have been successfully employed to introduce exogenous genes into an agricultural plant of interest, besides allowing better understanding regarding the role of different genes and metabolic pathways (Vayda and Belknap, 1992;Torres et al, 2000;Romano et al, 2001;Homrich et al, 2012). Regeneration of feasible plantlets is a limiting step of genetic transformation protocols and most of the tissue culture process is highly genotype dependent.…”

Resistance of genetically modified potatoes to Potato virus Y under field conditions

“…Achat for their resistance to PVY (Romano et al, 2001) No artificial inoculation of the GM and the nontransformed control plants were made, and only the natural spread by the virus vector (aphids) was recorded. The experiment was monitored weekly by visual inspections.…”

“…Since 1994, Embrapa has been working on the development of genetically modified (GM) potatoes transformed with the Potato virus Y (PVY) coat protein gene, and two potato Achat clones (named 1P and 63P) were selected for expressing resistance to PVY under greenhouse conditions (Romano et al, 2001). Both clones are being submitted to environmental and food safety risk assessment analyses as part of a biosafety project of Embrapa.…”

GENETIC APPROACHES FOR ENGINEERING BIOTIC STRESS RESISTANCE IN POTATO (Solanum tuberosum L.)

“…When overexpressed under the control of 35S promoter in potato variety "Russet Burbank" slowed down the symptom of PVY infection (Duan et al, 2012). Romano et al (2001) developed potatoes resistant against two Brazilian PVY strains by engineering with coat protein (CP) gene of PVY O . Dusi et al (2009) investigated the resistance in these transgenic lines for three consecutive years under the field condition.…”