Reproduction and horticultural performance of transgenic ethylene-insensitive petunias

A series of experiments on ethylene-insensitive (EI) petunia plants (Petuni a xhybrida Hort. Vilm.-Andr.) generated in two genetic backgrounds were con ducted to determine the involvement of ethylene in horticultural performanc e. Experiments examined various aspects of horticultural performance: days to flower, flower senescence after pollination and without pollination, fru it set and ripening, and adventitious root formation on vegetative stem cut tings. The development of EI plants was altered in several ways, Time from seed sowing to first flower anthesis was decreased by a week for EI plants grown at 26/21 degrees C. Flower senescence ill nonpollinated and self-poll inated flowers was delayed in all EI plants compared to wild-type plants. F ruit set percentage on EI plants was slightly lower than on wildtype plants and fruit ripening on EI plants was delayed by up to 7 days. EI plants pro duced fewer commercially acceptable rooted cuttings than wild-type plants. There was a basic difference in the horticultural performance of the two EI lines examined due to a difference in the genetic backgrounds used to gene rate the lines. EI plants displayed better horticultural performance when g rown with day/night temperatures of 26/21 degrees C than 30/24 degrees C. T hese results suggest that tissue-specific ethylene insensitivity as well as careful consideration of the genetic background used in transformation pro cedures and growth conditions of etr1-1 plants will be required to produce commercially viable transgenic floriculture crops. EI petunias provide an i deal model system for studying the role of ethylene in regulating various a spects of plant reproduction.