transgenic tobacco

ABSTRACT: The coat protein (CP) gene and 3 ' end untranslated region of Potato virus Y (PVY) were cloned into two plant transformation vectors (pPVSTIII and pBinAR) in both sense and antisense direction. One sense and three antisense constructs (CpS1, CpAS1, CpAS2 and CpAS3) were selected for the transformation of tobacco (Nicotiana tabacum) cvs White Burley and Xanthi via Agrobacterium tumefaciens mediated gene transfer. Analysis of the transformed plants by nucleic acid spot hybridization showed that 37 out of 77 plants were positive for gene incorporation. Southern analysis of the transformed plants confirmed the incorporation of CP gene into host chromosome and in some lines more than one copy number of transgene was obs.erved. Translated protein product of CP gene was, however not detected in any of the transgenic lines. Of the 17 transgenic lines tested for resistance to PVY, five antisense lines were completely resistant as these were not infected up to 30 days, 10 lines (two sense and eight antisense) showed varied degree of resistance and two antisense lines were susceptible. Infection in the resistant lines varied from 13-56% and in five such lines symptom development was delayed. Key words: Coat protein mediated resistance, Potato virus Y, transgenic tobacco, coat protein gene Potato virus Y (PVY), the type species of genus Potyvirus belonging to family Potyviridae, causes significant yield losses in a number of economically important crops in India and other countries (de Bokx and Huttinga, 1981; Varma, 1988). Management of the diseases caused by PVY is difficult, because it requires integration of various approaches like the avoidance of sources of infection, avoidance and control of vectors, modification of cultural practices and use of resistant varieties (Varma, 1993). The use of resistant varieties is the most important component of integrated management of viral diseases. However, conventional breeding of plant varieties resistant to potyviruses is extremely difficult due to frequent emergence of new strains of the viruse