Increased Flower Longevity in Petunia with Male Sterility

Abstract

Flower longevity is an important character in many ornamental crops. The processes of pollination and fertilization can cause senescence of the petals through the action of ethylene or its precursors. Preventing the production of pollen and therefore pollination could delay the senescence of petals. We tested whether male-sterility would increase flower longevity in petunia. The gene consisted of a stamen-specific promoter isolated from a Lycopersicon esculentum gene driving the expression of a barnase. Barnase is a RNase that is cytotoxic. The gene was introduced into `Lavender Storm' and `Purple Wave' petunia by Agrobacterium- mediated gene transfer. Five independent transgenic lines of both cultivars were regenerated, rooted, and grown in a greenhouse. All lines showed complete male-sterility as measured by the lack of detectable pollen. Two transgenic lines and a non-transformed control of each cultivar were propagated vegetatively and the flower longevity of each genotype was determined in a greenhouse experiment. There were two treatments: no pollination or pollination with cross-compatible pollen. All sterile genotypes that were not pollinated had increased flower longevity relative to pollinated sterile flowers or either treatment of male fertile (non-transformed) genotypes. These results indicate an application for sterility in the production of petunia flowers with increased longevity. Male and female sterility may be applicable in other ornamental crops where pollination or fertilization is a trigger to petal senescence.