Comparative Studies on the Anatomical Morphology between Asparagus officinalis L. and A. cochinchinensis with Different Genders

PurposeIn order to analyze the characteristics of sex differentiation between Asparagus officinalis L. and A. cochinchinensis.

MethodThe morphology of the anatomical development of the flower buds of A. officinalis ‘purple passion’ cultivar at six different stages of three gender plants (female, male and bisexual), the flower buds of the sibling plant A. cochinchinensis at early and late stages of three gender plants (female, male and bisexual) and the anthers of bisexual flowers of A. officinalis were studied by using paraffin section and microscopic examination technology.

ResultThe abortion of anther in A. officinalis female flowers occurred at stage 2 (1 mm≤length < 2 mm), the stigma stopped developing in male flowers at stage 3 (2 mm≤length < 3 mm), and the mature pollen in bisexual flowers is fertile. At the same time, the anatomical studies on A. cochinchinensis showed that the female flowers have obvious abortive stamen residues, the male flowers have degenerated stigma structure and the structure of bisexual flowers is similar as that of A. officinalis bisexual flowers.

ConclusionThe key nodes for A. officinalis sex differentiation were determined morphologically. The stage before 1mm diameter of female flower buds is the key point of female sex determination. The stage of male flower bud diameter less than 2 mm is the key point for its sex determination. The process of unisexual flower production in A. cochinchinensis was consistent with A. officinalis. This study lays a foundation for elucidating the sex determination mechanism in Asparagus spp. and provides the anatomical evidence support for searching for excellent material in all-male breeding.