Botanical Gardens, Graduate School of Science, The University of Tokyo, 3-7-1 Hakusan, Bunkyo-ku, Tokyo, 112-0001, Japan.
J Plant Res. 2013 Jul;126(4):469-82. doi: 10.1007/s10265-012-0540-4. Epub 2012 Dec 6.
In ferns, intra-gametophytic selfing occurs as a mode of reproduction where two gametes from the same gametophyte form a completely homozygous sporophyte. Intra-gametophytic selfing is considered to be prevented by lethal or deleterious recessive genes in several diploid species. In order to investigate the modes and tempo of selection acting different developmental stages, doubled haploids obtained from intra-gametophytic selfing within isolated gametophytes of a putative F1 hybrid between Osmunda japonica and O. lancea were analyzed with EST_derived molecular markers, and the distribution pattern of transmission ratio distortion (TRD) along linkage map was clarified. As the results, the markers with skewness were clustered in two linkage groups. For the two highly distorted regions, gametophytes and F2 population were also examined. The markers skewed towards O. japonica on a linkage group (LG_2) showed skewness also in gametophytes, and the TRD was generated in the process of spore formation or growth of gametophytes. Also, selection appeared to be operating in the gametophytic stage. The markers on other linkage group (LG_11) showed highest skewness towards O. lancea in doubled haploids, and it was suggested that the segregation of LG_11 were influenced by zygotic lethality or genotypic evaluation and that some deleterious recessive genes exist in LG_11 and reduce the viability of homozygotes with O. japonica alleles. It is very likely that a region of LG_11were responsible for the low frequencies of intra-gametophytic selfing in O. japonica.
在蕨类植物中，同配子体自交是一种繁殖方式，其中来自同一个配子体的两个配子形成一个完全纯合的孢子体。在几个二倍体物种中，同配子体自交被认为是由致死或有害的隐性基因所阻止的。为了研究不同发育阶段的选择模式和速度，从 Osmunda japonica 和 O. lancea 之间假定的 F1 杂种的隔离配子体中的同配子体自交获得的加倍单倍体，利用 EST 衍生的分子标记进行了分析，并阐明了传递率偏倚 (TRD) 在连锁图谱上的分布模式。结果表明，具有偏度的标记聚类在两个连锁群中。对于两个高度偏倚的区域，还检查了配子体和 F2 群体。在一个连锁群（LG_2）上偏向 O. japonica 的标记也在配子体中表现出偏度，并且在孢子形成或配子体生长过程中产生了 TRD。此外，选择似乎在配子体阶段起作用。其他连锁群（LG_11）上的标记在加倍单倍体中对 O. lancea 的偏度最高，表明 LG_11 的分离受到合子致死或基因型评估的影响，并且 LG_11 中存在一些有害的隐性基因，降低了具有 O. japonica 等位基因的纯合子的生存能力。很可能是 LG_11 的一个区域负责 O. japonica 中同配子体自交的频率较低。
