Studies on the break of self-incompatibility and seed abortion by 'Nishiuchi Konatsu' Hyuganatsu self-pollination

Hyuganatsu （Citrus tamurana short ex Tanaka）最初是自不相容的。它的芽突变‘Nishiuchi Konatsu’是自交的，当‘Nishiuchi Konatsu’自花授粉时，种子在发育过程中流产。我们假设在“西内Konatsu”中存在未还原的花粉。因此，我们研究了‘西内小松’及其后代的花粉萌发、花粉直径和倍性水平。在花粉萌发试验中，与其他品种相比，西内小松花粉具有正常的萌发能力。然而，据透露，“西内Konatsu”部分产生了巨大的花粉，这是许多其他植物物种中存在未还原花粉的证据。在流式细胞术分析倍性水平时，‘Nishiuchi Konatsu’本身为二倍体。而“西内Kontasu”自花授粉种子发育后的幼苗均表现为四倍体。这些结果表明，“西内Konatsu”产生了部分未还原花粉，只有未还原花粉才能到达胚珠进行杂交。只有当胚珠未还原性花粉未还原性花粉受精时，种子才能成功发育为四倍体。

Hyuganatsu (Citrus tamurana hort ex Tanaka) is originally self-incompatible. Its bud mutation 'Nishiuchi Konatsu' is self-compatible and seed is aborted during its development when 'Nishiuchi Konatsu' is self-pollinated. We assumed the presence of unreduced pollen in 'Nishiuchi Konatsu'. Thus we studied pollen germination, pollen diameter, and ploidy level of 'Nishiuchi Konatsu' and its progenies. In the result of pollen germination test, 'Nishiuchi Konatsu' pollen has normal germination ability compared with other varieties. However, it was revealed that 'Nishiuchi Konatsu' partially produced giant pollen, which is the proof of the presence of unreduced pollen in many of other plant species. In the flowcytometry analysis for ploidy level, 'Nishiuchi Konatsu' itself was diploid. However, all the seedlings from the developed seed of 'Nishiuchi Kontasu' self-pollination indicated tetraploidy. These results suggested that 'Nishiuchi Konatsu' produced unreduced pollen in part and only unreduced pollen can reach to the ovule to hybridize. Only when ovule fertilized with unreduced pollen was unreduced, seed was successfully developed to be indicated tetraploid by flowcytometry.