扭肚藤非典型二型花柱及自交不亲和研究

Atypical Distyly and Self-incompatibility Studies in Jasminum elongatum

摘要:

素馨属扭肚藤(Jasminum elongatum)是一种攀援灌木，常见于我国华南地区常绿阔叶林中及林缘地带。为探讨扭肚藤繁育系统特性，对其野外居群的长柱型和短柱型花部特征、花粉量/胚珠比和柱头附属多态性、人工授粉亲和性和花粉管生长情况进行研究。结果表明，长花柱型和短花柱型的花柱高度、柱头高度、花药高度、花冠筒直径和花冠筒长度均差异显著，花粉粒和柱头的附属特征观察表明2种花型的花粉大小、纹饰具有花粉二型性，柱头大小和形态具有柱头二型性。人工授粉后，长/短柱型花型间异交授粉生长正常，授粉8 h花粉管可进入子房，而自交和型内异交均表现出不亲和，花粉管分别抑制在短柱型柱头表面、长柱型柱头中，花粉管变形膨大且顶端累积胼胝质。因此，扭肚藤在形态上是非典型二型花柱，且具有严格的异型自交不亲和系统。

Abstract:

Jasminum elongatum is a climbing shrub, usually grows in the evergreen broad-leaved forests and forest edges in south China. In order to understand the sexual system and reproductive characters of J. elongatum, the distylous floral morphology, pollen-ovule ratios, ancillary floral characters, inter- and intra-morph incompatibility were studied. The results showed that there are significant differences between L- and S-morph in style length, stigma and anther heights, corolla tube diameter, and corolla tube length. The flower of J. elongatum showed pollen dimorphism in terms of size and ornamentation, and stigmatic dimorphism in terms of size and shape. After artificial pollination, the inter-type cross-pollination between long-styled and short-styled flowers grew normally, and the pollen tubes could enter the ovary after pollination 8 hours. However, self-pollination and intra-type cross-pollination showed incompatibility. The pollen tubes were inhibited on the surface of the S-morph stigma and in the middle of L-morph stigma respectively, and the pollen tubes were deformed and swollen with callose accumulation at the tip. Therefore, the flower of J. elongatum was atypical dimorphic style in morphology and had a strict heteromorphic self-incompatibility system.