Hybridization of closely related plant species is frequently connected to endosperm arrest and seed failure, for reasons that remain to be identified. In this study, we investigated the molecular events accompanying seed failure in hybrids of the closely related species pair Capsella rubella and C. grandiflora. Mapping of QTL for the underlying cause of hybrid incompatibility in Capsella identified three QTL that were close to pericentromeric regions. We investigated whether there are specific changes in heterochromatin associated with interspecific hybridizations and found a strong reduction of chromatin condensation in the endosperm, connected with a strong loss of CHG and CHH methylation and random loss of a single chromosome. Consistent with reduced DNA methylation in the hybrid endosperm, we found a disproportionate deregulation of genes located close to pericentromeric regions, suggesting that reduced DNA methylation allows access of transcription factors to targets located in heterochromatic regions. Since the identified QTL were also associated with pericentromeric regions, we propose that relaxation of heterochromatin in response to interspecies hybridization exposes and activates loci leading to hybrid seed failure.

• MeSH
• Capsella klasifikace   genetika   MeSH
• centromera genetika   MeSH
• chromatin genetika   metabolismus   MeSH
• chromozomální aberace MeSH
• druhová specificita MeSH
• endosperm genetika   MeSH
• heterochromatin genetika   metabolismus   MeSH
• hybridizace genetická * MeSH
• lokus kvantitativního znaku genetika   MeSH
• metylace DNA MeSH
• regulace genové exprese u rostlin MeSH
• rostlinné geny genetika   MeSH
• semena rostlinná genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chromatin MeSH
• heterochromatin MeSH

In plants, genome duplication followed by genome diversification and selection is recognized as a major evolutionary process. Rapid epigenetic and genetic changes that affect the transcription of parental genes are frequently observed after polyploidization. The pattern of alternative splicing is also frequently altered, yet the related molecular processes remain largely unresolved. Here, we study the inheritance and expression of parental variants of three floral organ identity genes in allotetraploid tobacco. DEFICIENS and GLOBOSA are B-class genes, and AGAMOUS is a C-class gene. Parental variants of these genes were found to be maintained in the tobacco genome, and the respective mRNAs were present in flower buds in comparable amounts. However, among five tobacco cultivars, we identified two in which the majority of paternal GLOBOSA pre-mRNA transcripts undergo exon 3 skipping, producing an mRNA with a premature termination codon. At the DNA level, we identified a G-A transition at the very last position of exon 3 in both cultivars. Although alternative splicing resulted in a dramatic decrease in full-length paternal GLOBOSA mRNA, no phenotypic effect was observed. Our finding likely serves as an example of the initiation of homoeolog diversification in a relatively young polyploid genome.

• Klíčová slova
• Alternative splicing, Floral genes, Flowering, Polyploidy, Tobacco,
• MeSH
• alternativní sestřih genetika   MeSH
• bodová mutace genetika   MeSH
• exony genetika   MeSH
• genetická transkripce * MeSH
• homeodoménové proteiny biosyntéza   genetika   MeSH
• nukleotidy genetika   MeSH
• polyploidie MeSH
• prekurzory RNA genetika   MeSH
• regulace genové exprese u rostlin MeSH
• rostlinné proteiny biosyntéza   genetika   MeSH
• tabák genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• GLOBOSA protein, plant MeSH Prohlížeč
• homeodoménové proteiny MeSH
• nukleotidy MeSH
• prekurzory RNA MeSH
• rostlinné proteiny MeSH

Developmental processes are closely connected to certain states of epigenetic information which, among others, rely on methylation of chromatin. S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are key cofactors of enzymes catalyzing DNA and histone methylation. To study the consequences of altered SAH/SAM levels on plant development we applied 9-(S)-(2,3-dihydroxypropyl)-adenine (DHPA), an inhibitor of SAH-hydrolase, on tobacco seeds during a short phase of germination period (6 days). The transient drug treatment induced: (1) dosage-dependent global DNA hypomethylation mitotically transmitted to adult plants; (2) pleiotropic developmental defects including decreased apical dominance, altered leaf and flower symmetry, flower whorl malformations and reduced fertility; (3) dramatic upregulation of floral organ identity genes NTDEF, NTGLO and NAG1 in leaves. We conclude that temporal SAH-hydrolase inhibition deregulated floral genes expression probably via chromatin methylation changes. The data further show that plants might be particularly sensitive to accurate setting of SAH/SAM levels during critical developmental periods.

• MeSH
• adenin analogy a deriváty   toxicita   MeSH
• adenosylhomocysteinasa antagonisté a inhibitory   metabolismus   MeSH
• DNA primery genetika   MeSH
• epigeneze genetická účinky léků   fyziologie   MeSH
• klíčení účinky léků   fyziologie   MeSH
• komplementární DNA genetika   MeSH
• květy anatomie a histologie   fyziologie   MeSH
• metylace DNA MeSH
• neparametrická statistika MeSH
• pyl fyziologie   MeSH
• regulace genové exprese u rostlin účinky léků   genetika   fyziologie   MeSH
• rostlinné proteiny metabolismus   MeSH
• Southernův blotting MeSH
• tabák enzymologie   fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 9-(2,3-dihydroxypropyl)adenine MeSH Prohlížeč
• adenin MeSH
• adenosylhomocysteinasa MeSH
• DNA primery MeSH
• GLO protein, Nicotiana tabacum MeSH Prohlížeč
• komplementární DNA MeSH
• rostlinné proteiny MeSH

BACKGROUND: The haploid male gametophyte generation of flowering plants consists of two- or three-celled pollen grains. This functional specialization is thought to be a key factor in the evolutionary success of flowering plants. Moreover, pollen ontogeny is also an attractive model in which to dissect cellular networks that control cell growth, asymmetric cell division and cellular differentiation. Our objective, and an essential step towards the detailed understanding of these processes, was to comprehensively define the male haploid transcriptome throughout development. RESULTS: We have developed staged spore isolation procedures for Arabidopsis and used Affymetrix ATH1 genome arrays to identify a total of 13,977 male gametophyte-expressed mRNAs, 9.7% of which were male-gametophyte-specific. The transition from bicellular to tricellular pollen was accompanied by a decline in the number of diverse mRNA species and an increase in the proportion of male gametophyte-specific transcripts. Expression profiles of regulatory proteins and distinct clusters of coexpressed genes were identified that could correspond to components of gametophytic regulatory networks. Moreover, integration of transcriptome and experimental data revealed the early synthesis of translation factors and their requirement to support pollen tube growth. CONCLUSIONS: The progression from proliferating microspores to terminally differentiated pollen is characterized by large-scale repression of early program genes and the activation of a unique late gene-expression program in maturing pollen. These data provide a quantum increase in knowledge concerning gametophytic transcription and lay the foundations for new genomic-led studies of the regulatory networks and cellular functions that operate to specify male gametophyte development.

• MeSH
• Arabidopsis genetika   MeSH
• CDC geny MeSH
• genetická transkripce genetika   MeSH
• genom rostlinný MeSH
• haploidie * MeSH
• homeodoménové proteiny genetika   MeSH
• proteiny huseníčku genetika   MeSH
• pyl genetika   MeSH
• rostlinné geny genetika   MeSH
• sekvenční analýza hybridizací s uspořádaným souborem oligonukleotidů metody   MeSH
• spory genetika   MeSH
• stanovení celkové genové exprese metody   MeSH
• transkripční faktory genetika   MeSH
• vývojová regulace genové exprese genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• homeodoménové proteiny MeSH
• KNAT5 protein, Arabidopsis MeSH Prohlížeč
• proteiny huseníčku MeSH
• transkripční faktory MeSH