| Currently the United States potato storage industry relies on isopropyl N-(3-chlorophenyl)carbamate (CIPC), a possibly toxic chemical, to control sprouting. Reregistration with the EPA is uncertain, and there is currently no adequate replacement for CIPC. The following study examines the role of the plant hormone ethylene in potato (Solanum tuberosum L.) growth and development, with an ultimate goal of extending tuber dormancy.; Internodes from potato cvs. Russet Burbank (RB) and Gem Russet (GR) were transformed via Agrobacterium tumefacians infection with the Arabidopsis etr1 cDNA, in either sense or antisense orientation, controlled by either the CaMV 35S promoter or the patatin promoter. Transgenic clones were propagated using standard tissue culture techniques, and grown to maturity in the greenhouse. Tubers were harvested, stored at 20°C, 85–90% RH, and monitored for dormancy release and sprouting characteristics indicative of changes in ethylene response. Selected clones of cv. RB were characterized for gene copy number, mRNA expression, protein expression, plant early growth and development, and tuber sprouting characteristics. Clones of both cultivars were observed for changes in: dormant period, plant and tuber morphology, and response to environmental stresses.; Transgenic clones exhibited signs of ethylene hypersensitivity including small leaves, small, elongated, or knobby tubers, dwarfism, changes in leaf color and leaf shape, heightened susceptibility to pathogens, phototropic leaf twisting, early senescence (cv. GR), and ease in sprout detachment (indicative of ethylene exposure). Both sense and antisense RB 35S clones showed differences in total plant dry weight that ranged from 58% less than controls to 49% more than controls. One 35S sense clone produced a significantly greater number of sprouts/tuber and these sprouts an average 58% reduction in total plant dry weight, sense clones 1S, 2S and 4S, 49% reduction; sense clone 8S produced 49% more dry weight and 41% more leaf area; and in sense clone IS, sprout number/tuber was 144%, sprout number/tuber 174%, average length/sprout/tuber 47%, and weight/mm sprout length 72% greater than controls. RB tuber dormancy was unaffected, but three GR clones showed extended dormant periods up to 22 weeks.; Overexpression of Arabidopsis etr1 in potato appears to alter ethylene sensitivity and response and may be cultivar dependent. The impact of ethylene on dormancy remains unclear. |
