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Zygotic Icthal factors in intraspecific crosses and reproductive isolation of hybrid inviability between mating-groups of Closterium ehrenbergii.

合子 Icthal 因素影响新月藻交配群体之间的种内杂交和杂交不存活的生殖隔离。

基本信息

批准号：
04640636
负责人：
ICHIMURA Terunobu
金额：
$ 1.28万
依托单位：
HOKKAIDO UNIVERSITY (1993)The University of Tokyo (1992)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

We have studied biosystematically many and various populations of Closterium ehrenbergii sampled from paddy fields, ponds and lakes in Japan, Taiwan, Nepal and Australia, and recognized so far more than a dozen mating groups (from A to P) primarily based on sezual isolation. Morphological and cytological studies, as well as those on the reproductive barriers of pre- and post-zygotic isolation, clearly suggest that each mating group of this alga be a biological species. In this project, we focused to study two contrasting mating groups of Closterium ehrenbergii. Namely, one is Group A of which natural populations are subjected to the conditions that seasonal and/or occasional occurrences of drought and/or extremely high and low temperatures would select, at least once a hear, against any defective mutation that affects the sezual process of zygote formation and germination. The other is Group P of which natural populations are maintained for many years only by means of vegetative cell divisions without sexual reproduction.(1) Although both mating types, plus and minus, coexist in single localities in Europe, we have not yet found any place where both the two coexist and all the samples collected so far in Japan contained vegetative cells of only one mating type. Natural populations of only plus were found in north-eastern and central Hokkaido, Akita, Iwate, Yamagata and Fukushima, and those of only minus were found in south-western Hokkaido, Niigata, Nagano, Toyama, Yamanashi and Shizuoka. Based on crossings in almost all possible combinations among isolates from one natural population, we found a dominant or mating-type plus specific, asynaptic mutation.(2) Although we could not detect such lethal zygotic factors in Group A, we found strong inbreeding depression in selfing and backcrossing F_1 progeny to the same parental strains.

我们对采自日本、台湾、尼泊尔和澳大利亚的稻田、池塘和湖泊中的许多不同种群的艾氏新月浑藻进行了系统的生物系统研究，迄今已识别出十多个交配群(从A到P)，主要基于序列隔离。形态和细胞学研究，以及关于合子前和合子后隔离的生殖障碍的研究清楚地表明，这种藻类的每个交配群都是一个生物物种。在这个项目中，我们重点研究了两个截然不同的交配群。也就是说，一组是A组，自然种群受到季节性和/或偶尔发生的干旱和/或极高和极低的温度至少每年一次的选择，以对抗任何影响受精卵形成和萌发的连续过程的缺陷突变。另一种是P组，其自然种群仅通过营养细胞分裂维持多年，没有有性繁殖。(1)在欧洲，虽然正负两种交配型在同一地区共存，但我们还没有发现两种交配型共存的地方，到目前为止在日本收集的所有样本都只含有一种交配型的营养细胞。在北海道东北部和中部、秋田、岩手县、山形和福岛发现了只有正数的自然种群，在北海道西南部、新泻、长野、富山、山梨和静冈发现了只有负数的自然种群。基于同一自然群体分离株之间几乎所有可能的组合的杂交，我们发现了一个显性或交配型加特异的无突触突变。(2)虽然我们在A组中没有检测到这样的致死合子因子，但我们在相同亲本品系的自交和回交F_1代中发现了强烈的近交抑制。