NewLeaf Plus (R) Russet Burbank potatoes: replicase-mediated resistance to potato leafroll virus

Potato leafroll poleovirus and the Colorado potato beetle (Leptinotarsa decemlineata (Say)) are major pests of potato in the USA. The US Department of Agriculture estimates that over 50% of annual insecticide use on potato is applied to control the Colorado potato beetle and aphids that transmit potato leafroll virus (PLRV). To address this issue, Russet Burbank potatoes have bee genetically modified for a high level of resistance to infection and the resulting disease symptoms caused by PLRV and to feeding damage caused by the Colorado potato beetle. This resistance was achieved by the expression of the unmodified full-length replicase gene of PLRV and the cry3A insect control protein gene from Bacillus thuringiensis var. tenebrionis. Plant expression constructs containing various modifications of the PLRV replicase gene were produced during the development of this product. The genes in these constructs were a full-length unmodified replicase (open reading frame 2a/2b), an antisense orientation of the full-length cDNA, an open reading frame 1 translation of the full-length gene, and a gene truncation containing the 3' sense coding portion of the replicase gene. Growth chamber experiments demonstrated that transformation of plants with the full-length and 3' sense coding constructs substantially protected these potato plants from infection and disease symptoms caused by PLRV. The Russet Burbank potato expressing the full-length PLV replicase gene and the cry3A gene is a new potato product from NatureMark called NewLeaf Plus(R).