Identification and in silico characterization of soybean trihelix-GT and bHLH transcription factors involved in stress responses

Marina Borges Osorio,Maria Helena Bodanese-Zanettini,Márcia Margis-Pinheiro,Graciela Castilhos,Lauro Bücker-Neto,Beatriz Wiebke-Strohm,Andreia Carina Turchetto-Zolet

doi:10.1590/s1415-47572012000200005

Marina Borges Osorio, Maria Helena Bodanese-Zanettini + Show 5 more

Open Access

https://doi.org/10.1590/s1415-47572012000200005

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Abstract

Environmental stresses caused by either abiotic or biotic factors greatly affect agriculture. As for soybean [Glycine max (L.) Merril], one of the most important crop species in the world, the situation is not different. In order to deal with these stresses, plants have evolved a variety of sophisticated molecular mechanisms, to which the transcriptional regulation of target-genes by transcription factors is crucial. Even though the involvement of several transcription factor families has been widely reported in stress response, there still is a lot to be uncovered, especially in soybean. Therefore, the objective of this study was to investigate the role of bHLH and trihelix-GT transcription factors in soybean responses to environmental stresses. Gene annotation, data mining for stress response, and phylogenetic analysis of members from both families are presented herein. At least 45 bHLH (from subgroup 25) and 63 trihelix-GT putative genes reside in the soybean genome. Among them, at least 14 bHLH and 11 trihelix-GT seem to be involved in responses to abiotic/biotic stresses. Phylogenetic analysis successfully clustered these with members from other plant species. Nevertheless, bHLH and trihelix-GT genes encompass almost three times more members in soybean than in Arabidopsis or rice, with many of these grouping into new clades with no apparent near orthologs in the other analyzed species. Our results represent an important step towards unraveling the functional roles of plant bHLH and trihelix-GT transcription factors in response to environmental cues.

Highlights

Soybean [Glycine max (L.) Merril] is one of the most important crop species in the world
From the BLASTP search at Phytozome, using all 17 Arabidopsis Basic helix-loop-helix (bHLH) protein sequences from subgroup 25, 67 non-redundant homolog peptides were identified in the soybean genome
Using MEME, two other highly conserved motifs were identified among the soybean subgroup 25 sequences. They are formed by residues right adjacent to the bHLH domain and had been previously reported (Heim et al, 2003; Li et al, 2006; Carretero-Paulet et al, 2010; Pires and Dolan, 2010)

Summary

Introduction

Soybean [Glycine max (L.) Merril] is one of the most important crop species in the world. It is widely used for both human and animal consumption due to the high protein and oil contents of its grains. The potential for using soybean oil in renewable fuel production has emerged (Programa Nacional de Produção e Uso de Biodiesel). Since it belongs to the Fabaceae family, soybean takes part in the process of organic nitrogen fertilizer production through its symbiotic association with nitrogen-fixing bacteria (Gepts et al, 2005). The genetic variability found in soybean germplasm for those characteristics is restricted, which increases the vulnerability of this species to environmental stresses (Priolli et al, 2002; Miles et al, 2006)

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