Shiboleth, Y.M., Department of Virology, Agricultural Research Organization, Volcani Center, PO Box 6, Bet Dagan 50-250, Israel
Arazi, T., Department of Virology, Agricultural Research Organization, Volcani Center, PO Box 6, Bet Dagan 50-250, Israel
Wang, Y., Department of Virology, Agricultural Research Organization, Volcani Center, PO Box 6, Bet Dagan 50-250, Israel
Gal-On, A., Department of Virology, Agricultural Research Organization, Volcani Center, PO Box 6, Bet Dagan 50-250, Israel

Expression of bar, a phosphinothricin acetyltransferase, in plant tissues, leads to resistance of these plants to glufosinate ammonium based herbicides. We have created a bar expressing, attenuated zucchini yellow mosaic potyvirus-vector, AGII-Bar, to enable herbicide use in cucurbit fields. The parental vector, ZYMV-AGII, has been rendered environmentally safe by both disease-symptom attenuation and aphid-assisted virus transmission abolishment. The recombinant AGII-Bar virus-encoding cDNA, when inoculated on diverse cucurbits was highly infectious, accumulated to similar levels as AGII, and elicited attenuated AGII-like symptoms. Potted cucurbits inoculated with AGII-Bar became herbicide resistant about a week post-inoculation. Herbicide resistance was sustained in squash over a period of at least 26 days and for at least 60 days in cucumber grown in a net-house under commercial conditions. To test the applicability of AGII-Bar use in a weed-infested field, a controlled experiment including more than 450 plants inoculated with this construct, was performed. Different dosages of glufosinate ammonium were sprayed, 2 weeks after planting, on the foliage of melons, cucumbers, squash, and watermelons. AGII-Bar provided protection to all inoculated plants, of every variety tested, at each dosage applied, including the highest doses that totally eradicated weeds. This study demonstrates that AGII-Bar can be utilized to facilitate weed control in cucurbits and exemplifies the practical potential of attenuated virus-vector use in agriculture. © 2001 Elsevier Science B.V. All rights reserved.