Use of the growth retardant tetcyclacis for potato tuber formation in vitro

Abstract

The effects of the plant growth retardant tetcyclacis on in vitro tuber formation in potatoes was studied, using two different approaches: 1. tuber formation in various lines that did not or hardly form tubers under control conditions, and 2. tuber formation by the variety Bintje, which readily forms tubers. The ABA-deficient (droopy) lines of S. phureja hardly formed tubers without the addition of tetcyclacis. In the presence of this growth retardant tuberization was nearly 100%, within three weeks of in vitro culture, even in the absence of cytokinin. A series of somatic hybrids between S. tuberosum and S. brevidens, that did not form tubers in field and pot experiments, were tested. They all formed tubers in vitro in the presence of tetcyclacis. Stoloniferous shoots formed on single-node cuttings from in vitro grown Solanum tuberosum var Bintje plantlets were transferred to media containing a high level of sucrose. In the presence of tetcyclacis, tuber formation started after 4 days, reaching a maximum level of 80% at day 7. Tubers formed in the presence of tetcyclacis, accumulated starch and expressed several tuber-specific genes. These effects were fully antagonized by gibberellic acid. It is concluded that the growth retardant tetcyclacis is a potent tool in the study of tuber formation in potatoes.