%0 Journal Article
%T Species Origin of Genomic Factors in Nicotiana nudicaulis Watson Controlling Hybrid Lethality in Interspecific Hybrids between N. nudicaulis Watson and N. tabacum L
%A Hongshuo Liu
%A Wataru Marubashi
%J PLOS ONE
%D 2014
%I Public Library of Science (PLoS)
%R 10.1371/journal.pone.0097004
%X Hybrid lethality is expressed at 28ˇăC in the cross Nicotiana nudicaulisˇÁN. tabacum. The S subgenome of N. tabacum has been identified as controlling this hybrid lethality. To clarify the responsible genomic factor(s) of N. nudicaulis, we crossed N. trigonophylla (paternal progenitor of N. nudicaulis) with N. tabacum, because hybrids between N. sylvestris (maternal progenitor of N. nudicaulis) and N. tabacum are viable when grown in a greenhouse. In the cross N. trigonophyllaˇÁN. tabacum, approximately 50% of hybrids were vitrified, 20% were viable, and 20% were nonviable at 28ˇăC. To reveal which subgenome of N. tabacum was responsible for these phenotypes, we crossed N. trigonophylla with two progenitors of N. tabacum, N. sylvestris (SS) and N. tomentosiformis (TT). In the cross N. sylvestrisˇÁN. trigonophylla, we confirmed that over half of hybrids of N. sylvestrisˇÁN. trigonophylla were vitrified, and none of the hybrids of N. trigonophyllaˇÁN. tomentosiformis were. The results imply that the S subgenome, encoding a gene or genes inducing hybrid lethality in the cross between N. nudicaulis and N. tabacum, has one or more genomic factors that induce vitrification. Furthermore, in vitrified hybrids of N. trigonophyllaˇÁN. tabacum and N. sylvestrisˇÁN. trigonophylla, we found that nuclear fragmentation, which progresses during expression of hybrid lethality, was accompanied by vitrification. This observation suggests that vitrification has a relationship to hybrid lethality. Based on these results, we speculate that when N. nudicaulis was formed approximately 5 million years ago, several causative genomic factors determining phenotypes of hybrid seedlings were inherited from N. trigonophylla. Subsequently, genome downsizing and various recombination-based processes took place. Some of the causative genomic factors were lost and some became genomic factor(s) controlling hybrid lethality in extant N. nudicaulis.
%U http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0097004