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  • Author or Editor: D.W. Ramming x
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Abstract

Stone fruit breeding programs by the USDA have been a major source of improved peach and nectarine cultivars. A nearly complete turnover has occurred in locations, personnel, and cultivars in the 23 years since Havis reviewed these programs (15). It is appropriate to review the changes and note the progress that has been made in the last 2 decades.

Open Access

Abstract

Two isoenzyme systems, glucose phosphate isomerase and phosphoglucomutase, were identified for use as starch gel electrophoretic markers of plum × peach (Prunus salicina × Prunus persica) interspecific hybrids. Two distinct regions of banding were associated with each enzyme system. Different unique banding patterns for each species were observed for plum and peach at 3 of 4 banding regions. Interspecific hybrid plants exhibited hybrid enzyme patterns with bands from both plum and peach in each region. Consequently, interspecific plum × peach hybrid genotypes may be distinguished from parental plum or peach genotypes. These enzyme systems may be used in breeding programs to identify plum × peach hybrid seedlings.

Open Access

Immature grape embryos from early ripening genotypes of Vitis vinifera were successfully cultured in vitro on Difco orchid agar or a modified White's agar medium. Germination was increased in vitro for five genotypes from 0%, 7%, 11%, 12%, and 16% in vivo to 15%, 24%, 23%, 34%, and 24%, respectively. Subculturing embryos onto liquid culture from seeds that failed to germinate on agar also was possible. Differences in germination rates, as affected by pollen, were significant. This method will allow accelerated development of early ripening cultivars by allowing breeders to use such genotypes as females, as well as males.

Free access