部分野生杜鹃杂交授粉后花粉管生长状况分析

Analysis of pollen tube growth after pollination in some wild Rhododendron

以映山红(Rhododendron simsii)及锦绣杜鹃(Rhododendron pulchrum)为母本,分别与杜鹃属15种杜鹃进行杂交授粉试验,观察授粉后花粉在柱头上萌发与花粉管生长状况,分析杜鹃远缘杂交组合的亲和性.结果显示,所有父本花粉都能在映山红及锦绣杜鹃柱头表面附着并萌发,花粉管生长情况和异常花粉管的比率因父本不同而情况各异.与锦绣杜鹃组合相比,映山红组合花粉管到达花柱底部速度快、数量多,异常花粉管比率低,部分锦绣杜鹃杂交组合,花粉管在花柱中、上部生长受阻,表明映山红组合种间杂交亲和性较高.亲和性较差的杂交组合,花粉管生长易出现扭曲、螺旋、膨大、破裂以及胼胝质过多沉积等现象,但自交与种内杂交组合也存在各种花粉管生长异常状况.结果表明,花粉管异常的类型与杂交亲和性无直接联系,但异常花粉管出现的比率与杂交亲和性相关.

Rhododendron simsii and Rhododendron pulchrum as maternal parent were crossed with 15 wild Rhododendron species. In order to make clear the interspecific cross compatibility and pre -fertilization barriers, the growth of pollen tube on the stigma and into the style was observed under the epifluorescence microscopy. The results showed that pollens of all cross combinations could be attached and germinated on stigmas of R. simsii and R. pulchrum, however pollen tube growth and the ratio of abnormal pollen tubes were different due to varied male parents. Different abnormalities of arrested pollen tube tips have been detected, including colied, spiralling, swollen, burst, heavy callose deposition on the wall and so on. The growth rate of pollen tube was more rapidly among cross combinations with better cross compatibility such as self - pollination and intraspecific hybridization of R. simsii, and their pollen tubes reached the bottom of style canal more than the cross combinations with worse cross compatibility. Different regions in the style canal and the ovary loculus for expression of pollen tube arrest have been found according to the different crosscombinations. R. simsii as maternal parent, pollen tube of all cross combinations reached the bottom of style canal, although pollen tube abnormality exited in all cross combinations. R. pulchrum as maternal parent, pollen tube growth of several cross combinations was inhibited in upper and lower style canal, and the ratio of pollen tube abnormality was higher. The results indicated R. simsii as maternal parent had better cross compatibility than R. pulchrum. In addition, abnormalities types of arrested pollen tube tips had no concern with cross compatibility, even if inbred combination had abnormal situation of pollen tubes, but emergence ratio of abnormal pollen tube was related to cross compatibility.