‘金坠梨’自交亲和性突变机制的初步研究

 自交不亲和性品种鸭梨的芽变品种‘金坠梨’自花授粉能结实, 但其自交亲和性突变机制至今不祥。本研究结果表明, 鸭梨自花授粉结实率仅2% , 自花花粉管在花柱中上部已经停止生长, 而金坠梨自花授粉结实率高达76% , 自花的花粉管能正常生长至花柱基部; 鸭梨花柱能够接受金坠梨花粉并受精结实, 而金坠梨花柱却与鸭梨花粉杂交不亲和; 进一步鉴定出了鸭梨和金坠梨基于S-RNase基因的S基因型, 发现两者S基因型相同, 均为S₂₁S₃₄ ; 通过克隆两品种S-RNase基因cDNA全长序列并进行比较分析发现, 该两品种的1对雌蕊S-RNase基因在核苷酸序列上完全相同, 且S-RNase基因均正常表达, 表达量没有明显差异, 从分子水平上证实了金坠梨在花柱方面和鸭梨并无差异, 可能是花粉S 基因发生突变, 导致了自交不亲和性功能的丧失, 表现出自花授粉能够结实。

Mutational Mechanism of Self-compatible Pear Cultivar 'Jinzhuili' (Pyrus bretschneideri)

Jinzhuili (Z) is a naturally occurred self-compatible (SC) mutant from Yali (Y) , a China native leading cultivar displaying typical gametophytic self-incompatibility ( GSI). How Z mutated to SC is unclear to date. In the p resent study, field pollination tests were carried out under four crosses ( Z selfed,Yselfed, Z ×Y and Y ×Z) , and fruit setting percentage determined and pollen tube growth inspected under fluorescentmicroscope. It was observed that more than 76% flowers set fruits and many pollen tubes grewdown to the base of style in crosses of Z and YXZ, whereas fruit setting did not occurred and most pollen tubes were arrested at the upper part of style in the cross Y and ZXY. These results indicated that both Y and Z functioned normally in SI response on the stylar part and could reject competent Y pollen, but accep ted Z pollen。Furthermolecular analyses revealed that both Y and Z harbored S₂₁-and S₃₄-RNase, transcribed normally and were identical to one another in mRNA sequences of two S-RNase. All these data suggested that Zmostlikely lost pollen SI function, and its style behave normally in SI response as that of itswild type Y did. How pollen of Zmutated needs to be further investigated.