Broad Resistance toTospoviruses inTransgenic Tobacco Plants ExpressingThree Tospoviral Nucleoprotein Gene Sequences. Marcel Prins. Department of Virology, Wageningen Agricultural University, Binnenhaven 11, P. O. Box 8045, 6709 PD Wageningen. Peter de Haan(2), Rene Luyten,(1), Marco van Veller,(1) Mart Q. J. M. van Grinsven,(2) and Rob Goldbach(1). (1) Department of Virology, Wageningen Agricultural University, Binnenhaven 11, P. O. Box 8045, 6709 PD Wageningen ,(2) S & G Seeds, Division of Technology, Westeinde 62, P.O. Box 26, 1600 AA Enkhuizen, The Netherlands. MPMI 8:85-91. Accepted 13 September 1994. Copyright 1995 The American Phytopathological Society.

Transgenic tobacco plants have been obtained expressing nucleoprotein (N) gene sequences of three different tospovinises known to affect vegetable crops: tomato spotted wilt virus (TSWV), tomato chlorotic spot vims (TCSV), and groundnut ringspot virus (GRSV). The chimeric plant transformation vector used comprised the three viral N gene sequences, each with a copy of the CaMV 35S promoter and the nos terminator. Despite the high levels of homology between the different N gene sequences (74-82%) and the presence of repeated promoter and terminator sequences in this construct, unrearranged copies of this triple N gene construct were stably maintained in both Escherichia coli and Agrobacterium tumefaciens plasmids used during the cloning process, as well as in several generations of transgenic tobacco plants. A transgenic tobacco line was obtained that exhibited high levels of resistance to all three tospoviruses, showing the possibility of producing transgenic plants with a broad resistance to tospoviruses by introducing tandemly cloned viral N gene sequences. DNA analysis of this transgenic plant line shows that the multivirus resistance trait is confined to a single genetic locus, which is very convenient for further breeding purposes.