Genes in S and T Subgenomes Are Responsible for Hybrid Lethality in Interspecific Hybrids between Nicotiana tabacum and Nicotiana occidentalis

Takahiro Tezuka,Wataru Marubashi,Robin Allaby

doi:10.1371/journal.pone.0036204

Takahiro Tezuka, Wataru Marubashi + Show 1 more

Open Access

https://doi.org/10.1371/journal.pone.0036204

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Journal: PloS one	Publication Date: Apr 26, 2012
Citations: 19	License type: CC BY 4.0

Affiliation: Osaka Prefecture University, Meiji University

Abstract

BackgroundMany species of Nicotiana section Suaveolentes produce inviable F1 hybrids after crossing with Nicotiana tabacum (genome constitution SSTT), a phenomenon that is often called hybrid lethality. Through crosses with monosomic lines of N. tabacum lacking a Q chromosome, we previously determined that hybrid lethality is caused by interaction between gene(s) on the Q chromosome belonging to the S subgenome of N. tabacum and gene(s) in Suaveolentes species. Here, we examined if hybrid seedlings from the cross N. occidentalis (section Suaveolentes)×N. tabacum are inviable despite a lack of the Q chromosome.Methodology/Principal FindingsHybrid lethality in the cross of N. occidentalis×N. tabacum was characterized by shoots with fading color. This symptom differed from what has been previously observed in lethal crosses between many species in section Suaveolentes and N. tabacum. In crosses of monosomic N. tabacum plants lacking the Q chromosome with N. occidentalis, hybrid lethality was observed in hybrid seedlings either lacking or possessing the Q chromosome. N. occidentalis was then crossed with two progenitors of N. tabacum, N. sylvestris (SS) and N. tomentosiformis (TT), to reveal which subgenome of N. tabacum contains gene(s) responsible for hybrid lethality. Hybrid seedlings from the crosses N. occidentalis×N. tomentosiformis and N. occidentalis×N. sylvestris were inviable.Conclusions/SignificanceAlthough the specific symptoms of hybrid lethality in the cross N. occidentalis×N. tabacum were similar to those appearing in hybrids from the cross N. occidentalis×N. tomentosiformis, genes in both the S and T subgenomes of N. tabacum appear responsible for hybrid lethality in crosses with N. occidentalis.

Highlights

Reproductive isolation involves various types of prezygotic and postzygotic barriers in plants [1]
Based on phenotypic and genetic analyses, we demonstrate that N. occidentalis exhibits a distinct type of hybrid lethality after crosses with N. tabacum than that observed with the nine Suaveolentes species examined in our previous studies
At 24uC, hybrid seedlings grew normally and developed cotyledons and roots by approximately 3 days after germination (DAG), root growth stopped at this stage (Figure 1A)

Summary

Introduction

Reproductive isolation involves various types of prezygotic and postzygotic barriers in plants [1]. Hybrid lethality is a type of postzygotic barrier and is observed in certain cross combinations in numerous plant species, including Nicotiana sp. The genus Nicotiana comprises 76 species that are predominantly distributed in the Americas and Australia [8]. Monosomic analyses have identified one N. tabacum chromosome containing a gene or genes that trigger hybrid lethality [20–22]. Many species of Nicotiana section Suaveolentes produce inviable F1 hybrids after crossing with Nicotiana tabacum (genome constitution SSTT), a phenomenon that is often called hybrid lethality. Through crosses with monosomic lines of N. tabacum lacking a Q chromosome, we previously determined that hybrid lethality is caused by interaction between gene(s) on the Q chromosome belonging to the S subgenome of N. tabacum and gene(s) in Suaveolentes species. We examined if hybrid seedlings from the cross N. occidentalis (section Suaveolentes)6N. tabacum are inviable despite a lack of the Q chromosome

Methods

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Conclusion