BackgroundGermin and germin-like proteins constitute a ubiquitous family of plant proteins. A role of some family members in defense against pathogen attack had been proposed based on gene regulation studies and transgenic approaches. Soybean (G. max L. Merr.) germin genes had not been characterized at the molecular and functional levels.ResultsIn the present study, twenty-one germin gene members in soybean cultivar 'Maple Arrow' (partial resistance to Sclerotinia stem rot of soybean) were identified by in silico identification and RACE method (GmGER 1 to GmGER 21). A genome-wide analyses of these germin-like protein genes using a bioinformatics approach showed that the genes located on chromosomes 8, 1, 15, 20, 16, 19, 7, 3 and 10, on which more disease-resistant genes were located on. Sequence comparison revealed that the genes encoded three germin-like domains. The phylogenetic relationships and functional diversity of the germin gene family of soybean were analyzed among diverse genera. The expression of the GmGER genes treated with exogenous IAA suggested that GmGER genes might be regulated by auxin. Transgenic tobacco that expressed the GmGER 9 gene exhibited high tolerance to the salt stress. In addition, the GmGER mRNA increased transiently at darkness and peaked at a time that corresponded approximately to the critical night length. The mRNA did not accumulate significantly under the constant light condition, and did not change greatly under the SD and LD treatments.ConclusionsThis study provides a complex overview of the GmGER genes in soybean. Phylogenetic analysis suggested that the germin and germin-like genes of the plant species that had been founded might be evolved by independent gene duplication events. The experiment indicated that germin genes exhibited diverse expression patterns during soybean development. The different time courses of the mRNAs accumulation of GmGER genes in soybean leaves appeared to have a regular photoperiodic reaction in darkness. Also the GmGER genes were proved to response to abiotic stress (such as auxin and salt), suggesting that these paralogous genes were likely involved in complex biological processes in soybean.

Germin-like proteins (GLPs) are ubiquitous plant glycoproteins (belonging to the cupin super family) that play diverse roles, including abiotic stress resistance in many plant species. To identify the molecular functions underlying abiotic stress responses, the expression of germin-like protein encoding genes of soybean GmGLPs was analyzed. qRT-PCR analyses of 21 GmGLPs transcripts abundances were conducted in soybean leave tissues. The results showed that GmGLPs transcripts were highly abundant upon treatments with high salinity, PEG6000, abscisic acid (ABA) and methyl viologen (MV). The peaks of transcript copiousness induced by PEG6000 and NaCl were mostly observed after 18 h, while some genes expressed earlier than 4 h after abiotic stress treatment. A specific GmGLP7 gene, that was highly abundant under salinity, drought, ABA and MV conditions, was further characterized. The ectopic overexpression of GmGLP7 (Glyma.08G226800.1) in transgenic Arabidopsis enhanced drought, salt, and oxidative tolerance and resulted in hypersensitive phenotypes toward ABA-mediated seed germination and primary root elongation, compared to the wild-type. Taken together, these results suggest that GmGLP7 positively confers abiotic tolerance in plants.Key words: GmGLP, abiotic stress, Arabidopsis, soybean.Résumé : Les protéines semblables à la germine (GLP) sont des glycoprotéines végétales (de la super famille des cupines). Omniprésentes, elles assument divers rôles, notamment la résistance aux stress abiotiques chez maintes espèces de plantes. Les auteurs ont analysé l'expression des gènes qui codent les GmGLP du soja afin de préciser la fonction moléculaire qui sous-tend la réaction aux stress abiotiques. Pour cela, ils ont quantifié 21 transcrits de GmGLP dans les tissus foliaires du soja par la technique de la réaction en chaîne de la polymérase quantitative (qRT-PCR). Les résultats indiquent que les transcrits de GmGLP abondent après un traitement à salinité élevée et avec du PEG6000, de l'acide abscissique (ABA) ou du méthyl viologène (MV). La concentration maximale de transcrits induits par le PEG6000 et le NaCl survient 18 h après le traitement, bien que certains gènes s'expriment plus rapidement (quatre heures après le stress abiotique). Les auteurs ont caractérisé un gène spécifique à la GmGLP7, très abondante quand il y a salinité, sécheresse ou présence d'ABA ou de MV. La surexpression ectopique de la GmGLP7 (Glyma.08G226800.1) chez les sujets transgéniques d'Arabidopsis accroît la tolérance à la sécheresse, au sel et aux oxydants, et engendre des phénotypes hypersensibles au niveau de la germination des graines activée par l'ABA et de l'élongation des racines primaires, comparativement au phénotype sauvage. Combinés, ces résultats laissent croire que la GmGLP7 confère une tolérance positive aux stress abiotiques chez la plante. [Traduit par la Rédaction]

The membrane protein Dispatched (Disp), which belongs to the RND family of small molecule transporters, is essential for Hedgehog (Hh) signaling, by catalyzing the extracellular release of palmitate- and cholesterol-modified Hh ligands from producing cells. Disp function requires Furin-mediated proteolytic cleavage of its extracellular domain, but how this activates Disp remains obscure. Here, we employ cryo-electron microscopy to determine atomic structures of human Disp1 (hDisp1), before and after cleavage, and in complex with lipid-modified Sonic hedgehog (Shh) ligand. These structures, together with biochemical data, reveal that proteolytic cleavage opens the extracellular domain of hDisp1, removing steric hindrance to Shh binding. Structure-guided functional experiments demonstrate the role of hDisp1–Shh interactions in ligand release. Our results clarify the mechanisms of hDisp1 activation and Shh morphogen release, and highlight how a unique proteolytic cleavage event enabled acquisition of a protein substrate by a member of a family of small molecule transporters.

In line 12 of page 1, replace "GmGER 9" with "GmGER 15".