椪柑无核优系的细胞学研究

Cytological mechanisms of the elite seedless Ponkan accessions

以椪柑无核优系(Citrus reticulate Blanco)及其母本江西靖安有核椪柑(C.reticulate Blanco)、鄂柑1号(C.reticulate Blanco)为材料,从花粉形态、授粉亲和性和合子胚发育等方面研究优系无核机制。结果表明:无核优系花粉母细胞减数分裂异常比例显著高于其母本,花粉粒形态和小孢子母细胞的解剖学结构与母本有明显不同;无核优系自花授粉后的花粉管可以正常抵达花柱基部,自交亲和;无核优系胚胎早期败育,授粉后3周是败育主要时期;无核优系自花或异花授粉都不会产生种籽。无核优系果实无核的主要原因是胚胎早期败育。

The cytological mechanisms of the elite seedless Ponkan accession were systematically studied through comparing with its maternal parent Jiangxi Ponkan and E-gan No. 1. Male gamete fertility, self-incompatibility and embryo development were investigated. The results showed that male gamete of Jiangxi seedless Ponkan developed abnormally and the pollen fertility of the elite seedless Ponkan was significantly lower than that of the control. Meanwhile the abnormal meiosis percentage of pollen mother cell was severely higher than that of the control. Morphological and anatomical structure of microspore mother cell of the elite seedless Ponkan was different from that of the control. The seedless Ponkan ac- cession had self-compatibility and its pollen tubes grew downward through the style normally. Embryo abortion occurred at early developmental stage causing the seedlessness of the elite seedless accession. The 3rd week after pollination was the critical period to observe the embryo abortion. Seed numbers in fruit did not change significantly by self-pollination or cross-pollination. Embryo abortion is responsible for the elite seedless Ponkan accession.