Abstract
Intracellular vesicle trafficking genes, Rab, encoding small GTP binding proteins, have been well studied in medical research, but there is little information concerning these proteins in plants. Some sub-families of the Rab genes have not yet been characterized in plants, such as RabC – otherwise known as Rab18 in yeast and animals. Our study aimed to identify all CaRab gene sequences in chickpea (Cicer arietinum L.) using bioinformatics approaches, with a particular focus on the CaRabC gene sub-family since it featured in an SNP database. Five isoforms of the CaRabC gene were identified and studied: CaRabC-1a, -1b, -1c, -2a and -2a∗. Six accessions of both Desi and Kabuli ecotypes, selected from field trials, were tested for tolerance to abiotic stresses, including salinity, drought and rapid dehydration and compared to plant growth under control conditions. Expression analysis of total and individual CaRabC isoforms in leaves of control plants revealed a very high level of expression, with the greatest contribution made by CaRabC-1c. Salinity stress (150 mM NaCl, 12 days in soil) caused a 2-3-fold increased expression of total CaRabC compared to controls, with the highest expression in isoforms CaRabC-1c, -2a∗ and -1a. Significantly decreased expression of all five isoforms of CaRabC was observed under drought (12 days withheld water) compared to controls. In contrast, both total CaRabC and the CaRabC-1a isoform showed very high expression (up-to eight-fold) in detached leaves over 6 h of dehydration. The results suggest that the CaRabC gene is involved in plant growth and response to abiotic stresses. It was highly expressed in leaves of non-stressed plants and was down-regulated after drought, but salinity and rapid dehydration caused up-regulation to high and very high levels, respectively. The isoforms of CaRabC were differentially expressed, with the highest levels recorded for CaRabC-1c in controls and under salinity stress, and for CaRabC-1a – in rapidly dehydrated leaves. Genotypic variation in CaRabC-1a, comprising eleven SNPs, was found through sequencing of the local chickpea cultivar Yubileiny and germplasm ICC7255 in comparison to the two fully sequenced reference accessions, ICC4958 and Frontier. Amplifluor-like markers based on one of the identified SNPs in CaRabC-1a were designed and successfully used for genotyping chickpea germplasm.
Highlights
Plant genomes include a superfamily of genes that encode small GTP-binding proteins (Guanosine triphosphatases) that are classified into four groups: Arf, Rab, Ran and Rho; and an additional Ras-GTP gene group is found only in yeast and animals (Ma, 2007)
We present the results of bioinformatic analyses of the identified genes and tests conducted to assess the expression of all isoforms of the CaRabC gene family in response to salinity, drought and rapid dehydration in selected chickpea genotypes
The sequences of all 54 isoforms of CaRab genes identified in chickpea were used to construct a phylogenetic tree (Figure 1)
Summary
Plant genomes include a superfamily of genes that encode small GTP-binding proteins (Guanosine triphosphatases) that are classified into four groups: Arf, Rab, Ran and Rho; and an additional Ras-GTP gene group is found only in yeast and animals (Ma, 2007). Small GTP-binding proteins are known to be involved in a diverse range of activities in eukaryotes that are vital for growth, development and repair; from cytoskeletal organization, vacuolar storage and signaling, to modulation of gene expression (Takai et al, 2001). The mechanism for the regulation of GTPbinding proteins is conserved in all organisms and involves cycling between active (GTP-bound) and inactive (GDP-bound) forms, so they are often described as “molecular switches” that are turned “on” or “off ” via the hydrolysis of GTP (Marshall, 1993). Activation requires the dissociation of GDP, which can be either stimulated by a regulatory factor named GEP (GDP/GTP Exchange Protein) or inhibited by GDI (GDP Dissociation Inhibitor; Takai et al, 2001; Liu et al, 2015; Martín-Davison et al, 2017)
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
