Transgenic Burley and Flue-Cured Tobacco with Resistance to Four Necrotic Isolates of Potato Virus Y

Abstract

Transgenic burley (cultivars KY14, NC3433-33, and TN90) and flue-cured (cultivar K326) tobacco with resistance to four necrotic isolates of potato virus Y (PVY) were constructed. These tobacco cultivars were transformed with a chimeric gene designed to express the coat protein (CP) from the necrotic Chilean isolate of PVY. CP expression among R 0 plants was undetectable by indirect enzyme-linked immunosorbent assay and Western blot (immunoblot) analysis. Transgenic R 0 plants that harbored from one to five neomycin phosphotransferase II (NPT II) transgene loci were identified. Although the NPT II and the PVY CP chimeric genes were linked within a common T-DNA, no correlation was found between the number of NPT II and CP transgenes. Inoculation of 41 independent transgenic KY14 R 0 plants with PVY-Chilean identified eight resistant plants, while inoculation of 30 transgenic K326 R 0 plants identified six resistant plants. Inoculation of 17 transgenic NC3433-33 R 0 plants with PVY-Chilean identified six resistant plants, while inoculation of 50 transgenic TN90 R 0 plants with PVY isolate VAM B resulted in nine resistant plants. Progeny derived from PVY-inoculated but symptomless R 0 plants were also resistant to the Chilean, Europe H, M s N r , N-Canada, and VAM B isolates of PVY, demonstrating sexual transmission of the transgenes that condition resistance. We discuss the ability of the PVY-Chilean CP gene to protect transgenic tobacco K326, KY14, NC3433-33, and TN90 from infection by four necrotic isolates of PVY. The flue-cured tobacco cultivar K326, which carries a gene simultaneously conferring resistance against root-knot nematode and susceptibility to PVY strain M S N R , is protected against this strain when transformed with the PVY-Chilean CP gene.