Interspecific Hybridization of Impatiens

Abstract

<jats:p>An interspecific hybridization program involving five species of <jats:italic>Impatiens</jats:italic> was initiated to delineate incompatibility barriers. With the exception of one cross, no viable hybrid seed was recovered. Fluorescence microscopy revealed foreign pollen tubes to reach ovules in all crosses, although not all ovules were approached. A histological study involving <jats:italic>I. auricoma</jats:italic> Baill. and <jats:italic>I. walleriana</jats:italic> Hook f. ensued to confirm the presence of hybrid embryos. Developing <jats:italic>I. walleriana</jats:italic> × <jats:italic>I. auricoma</jats:italic> and reciprocal hybrid embryos were compared to self embryos. Development of hybrid embryos was delayed as early as five days post-pollination. <jats:italic>I. walleriana</jats:italic> × <jats:italic>I. auricoma</jats:italic> embryos continued to develop for 8 days post-pollination, but did not reach a size greater than a 5-day self embryo. Excessive endosperm was observed in the hybrid. <jats:italic>I. auricoma</jats:italic> × <jats:italic>I. walleriana</jats:italic> embryos continued to enlarge up to ovary abortion but did not reach a size greater than a 7-day self embryo and little to no endosperm developed. Disintegration of ovules included disorganization and collapse of the endosperm, and vacuolization and loss of turgidity of the embryo.</jats:p>