Abstract:
Incorporation of a gene or a transgene for parthenocarpy into tomato cultivars should confer them tolerance to environmental constrains on pollination dependent fruit set and development. Previously we have demonstrated that the chimeric transgene TPRPF1:: rolB, which is expressed predominantly in ovaries and young fruits, induced parthenocarpic competence to the tomato line MP-1. This line is highly amenable to transformation, yet it is not an advanced breeding line. In the present study this transgene was transformed into line CP-117, which is a parental line in many advanced indeterminate hybrid cultivars, and into the determinate processing cultivar UC82. Among the first eight transgenic plants derived from line CP-117, five manifested clear parthenocarpic phenotype: most or all their fruits were completely seedless, yet of size comparable to that of the parental line. The cultivar UC82 gave a very low transformation rate. Progenies of three transgenic plants where analyzed for yield and fruit characteristics. Although none showed obligate parthenocarpy, fruits of the transgenic lines, developed in the summer under high temperatures, were characterized by a substantially better jelly fill compared with UC82 control fruits which showed severe puffiness. The transgenic lines did not show a reduction in the yield. These results indicate that this transgene confers parthenocarpic competence and improves the quality of the fruit developed under fertilization restrictive conditions, both in determinate and indeterminate tomato cultivars.