Abstract
Cucumber (Cucumis sativus L.) is one of the most important cucurbit vegetables but is often subjected to stress during cultivation. GRAS (gibberellic acid insensitive, repressor of GAI, and scarecrow) genes encode a family of transcriptional factors that regulate plant growth and development. In the model plant Arabidopsis thaliana, GRAS family genes function in formation of axillary meristem and root radial structure, phytohormone (gibberellin) signal transduction, light signal transduction and abiotic/biological stress. In this study, a gene family was comprehensively analyzed from the aspects of evolutionary tree, gene structure, chromosome location, evolutionary and expression pattern by means of bioinformatics; 37 GRAS gene family members have been screened from cucumber. We reconstructed an evolutionary tree based on multiple sequence alignment of the typical GRAS domain and conserved motif sequences with those of other species (A. thaliana and Solanum lycopersicum). Cucumber GRAS family was divided into 10 groups according to the classification of Arabidopsis and tomato genes. We conclude that tandem and segmental duplication have played important roles in the expansion and evolution of the cucumber GRAS (CsaGRAS) family. Expression patterns of CsaGRAS genes in different tissues and under cold treatment, combined with gene ontology annotation and interaction network analysis, revealed potentially different functions for CsaGRAS genes in response to cold tolerance, with members of the SHR, SCR and DELLA subfamilies likely playing important roles. In conclusion, this study provides valuable information and candidate genes for improving cucumber tolerance to cold stress.
Highlights
Through screening the cucumber genome database, we identified 37 genes encoding GRAS protein domains
The GRAS gene family has been analyzed in many plants, such as tea (Camellia sinensis) [24]
We identified 37 GRAS genes in cucumber based on existing information about GRAS family proteins and a domain search in the gff3 of cucumber
Summary
Transcription factors, known as trans-acting elements, can activate or inhibit gene expression by binding to 50 -flank cis-elements of target genes, thereby regulating plant growth and development [1].The GRAS family of plant-specific transcription factors exists widely in plants [2], includingArabidopsis [3], grapevine (Vitis vinifera) [4], Chinese cabbage (Brassica rapa ssp. pekinensis) [5], tomato (Solanum lycopersicum) [6], lotus (Nelumbo nucifera) [7] and mustard (Brassica juncea) [8].Named for three functional proteins: GAI (gibberellic acid insensitive) [9], RGA (repressor of GA1-3 mutant) [10], and SCR (scarecrow) [11], proteins of the GRAS family generally comprise400–700 amino acids [12], this range is expanded in some species, e.g., 318–792 amino acids [8]in mustard. Transcription factors, known as trans-acting elements, can activate or inhibit gene expression by binding to 50 -flank cis-elements of target genes, thereby regulating plant growth and development [1]. The GRAS family of plant-specific transcription factors exists widely in plants [2], including. Pekinensis) [5], tomato (Solanum lycopersicum) [6], lotus (Nelumbo nucifera) [7] and mustard (Brassica juncea) [8]. Named for three functional proteins: GAI (gibberellic acid insensitive) [9], RGA (repressor of GA1-3 mutant) [10], and SCR (scarecrow) [11], proteins of the GRAS family generally comprise. Typical transcription factors are composed of a DNA-binding domain, transcriptional regulatory (activation or repression) domain, oligomerization site and nuclear localization signals [13]. GRAS proteins contain a variable N-terminal and a highly conserved C-terminal region.
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