RESUMO
The symbiosis between leguminous plants and soil rhizobia culminates in the formation of nitrogen-fixing organs called nodules that support plant growth. Two Medicago truncatula Tnt1-insertion mutants were identified that produced small nodules, which were unable to fix nitrogen effectively due to ineffective rhizobial colonization. The gene underlying this phenotype was found to encode a protein containing a putative membrane-localized domain of unknown function (DUF21) and a cystathionine-ß-synthase domain. The cbs1 mutants had defective infection threads that were sometimes devoid of rhizobia and formed small nodules with greatly reduced numbers of symbiosomes. We studied the expression of the gene, designated M truncatula Cystathionine-ß-Synthase-like1 (MtCBS1), using a promoter-ß-glucuronidase gene fusion, which revealed expression in infected root hair cells, developing nodules, and in the invasion zone of mature nodules. An MtCBS1-GFP fusion protein localized itself to the infection thread and symbiosomes. Nodulation factor-induced Ca(2+) responses were observed in the cbs1 mutant, indicating that MtCBS1 acts downstream of nodulation factor signaling. MtCBS1 expression occurred exclusively during Medicago-rhizobium symbiosis. Induction of MtCBS1 expression during symbiosis was found to be dependent on Nodule Inception (NIN), a key transcription factor that controls both rhizobial infection and nodule organogenesis. Interestingly, the closest homolog of MtCBS1, MtCBS2, was specifically induced in mycorrhizal roots, suggesting common infection mechanisms in nodulation and mycorrhization. Related proteins in Arabidopsis have been implicated in cell wall maturation, suggesting a potential role for CBS1 in the formation of the infection thread wall.
Assuntos
Cistationina beta-Sintase/metabolismo , Medicago truncatula/enzimologia , Medicago truncatula/microbiologia , Fixação de Nitrogênio , Proteínas de Plantas/metabolismo , Rhizobium/fisiologia , Simbiose , Cistationina beta-Sintase/química , Cistationina beta-Sintase/genética , Endocitose , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Proteínas de Fluorescência Verde/metabolismo , Medicago truncatula/genética , Mutação/genética , Fenótipo , Proteínas de Plantas/química , Proteínas de Plantas/genética , Nodulação , Regiões Promotoras Genéticas/genética , Domínios Proteicos , Nódulos Radiculares de Plantas/genéticaRESUMO
Funding agencies use many different criteria and peer review strategies to assess grant proposals.
Assuntos
Pesquisa Biomédica/economia , Financiamento de Capital/normas , Revisão da Pesquisa por Pares/normas , Austrália , Europa (Continente) , Humanos , Estados UnidosRESUMO
Journals and other scientific organizations produce a diverse variety of plain-language summaries.
Assuntos
Políticas Editoriais , Educação em Saúde/métodos , Publicações Periódicas como AssuntoRESUMO
After summarizing over 2,400 articles in plain language, the eLife Features team shares what it has learnt about writing and editing for a broad audience.