Gene Family In Tomato Research Articles

Genome-wide identification of FK506-binding domain protein gene family, its characterization, and expression analysis in tomato (Solanum lycopersicum L.)

FK506-protein also called FKBP protein belongs to PPIase (peptidylprolylcis-trans isomerase) super family of immune suppressive drugs that act as molecular protein chaperones. In plants, FKBPs are ubiquitous and involved in various biological and physiological processes like plant germination, development, stress response and hormonal signaling. Here, we identified 24 FKBP family genes in tomato by using different tools and bioinformatic approaches. The specific structure, domain organisation, cis-regulatory elements, phylogenetic analysis, multiple sequence alignment, tissue-specific expression patterns and expression under abiotic and phytohormone stresses of all genes were investigated. The genes are clustered on ten tomato chromosomes and are categorised into two sub-classes; single and multiple domains protein gene. One of the main features of tomato FKBPs is their large fractions localized in chloroplast (in silico analysis) and clustered together phylogenetically. Tissue-specific expression analysis using available RNA-seq data revealed the spatiotemporal expression of the FKBPs, but few genes were observed with relatively high expressions in certain developmental stages. However, the quantitative expression profile of all genes under hormone stress provided a supporting evidence for their potential role in hormone signal pathways. Our prediction not only providing the foundation for better understanding the complex physiological regulation of FKBP gene family in tomato but also providing the potential aids to accelerate tolerance and survival in tomato under stressful condition.

Genome-Wide Identification and Expression Analysis of the UGlcAE Gene Family in Tomato.

The UGlcAE has the capability of interconverting UDP-d-galacturonic acid and UDP-d-glucuronic acid, and UDP-d-galacturonic acid is an activated precursor for the synthesis of pectins in plants. In this study, we identified nine UGlcAE protein-encoding genes in tomato. The nine UGlcAE genes that were distributed on eight chromosomes in tomato, and the corresponding proteins contained one or two trans-membrane domains. The phylogenetic analysis showed that SlUGlcAE genes could be divided into seven groups, designated UGlcAE1 to UGlcAE6, of which the UGlcAE2 were classified into two groups. Expression profile analysis revealed that the SlUGlcAE genes display diverse expression patterns in various tomato tissues. Selective pressure analysis indicated that all of the amino acid sites of SlUGlcAE proteins are undergoing purifying selection. Fifteen stress-, hormone-, and development-related elements were identified in the upstream regions (0.5 kb) of these SlUGlcAE genes. Furthermore, we investigated the expression patterns of SlUGlcAE genes in response to three hormones (indole-3-acetic acid (IAA), gibberellin (GA), and salicylic acid (SA)). We detected firmness, pectin contents, and expression levels of UGlcAE family genes during the development of tomato fruit. Here, we systematically summarize the general characteristics of the SlUGlcAE genes in tomato, which could provide a basis for further function studies of tomato UGlcAE genes.

Genomic Analysis of the ASMT Gene Family in Solanum lycopersicum.

Acetylserotonin methyltransferase (ASMT) is the last enzyme of melatonin biosynthesis and may play a rate-limiting role in the melatonin production of plants. In this study, systematic analysis of the ASMT gene family in tomato (Solanum lycopersicum Mill) has been presented by the integration of the structural features, phylogenetic relationships, exon/intron configuration, and expression profile during growth and development, as well as biotic stresses. The results revealed that the tomato genome encoded a minimum of 14 members, containing three probable encoded pseudogenes. Chromosome mapping indicated that the family had probably expanded via tandem duplication events. Genome-wide RNA-seq and qRT-PCR based gene expression analysis revealed that almost half of the SlASMT genes were expressed in at least one of the experimental stages studied and also showed differential accumulation. Furthermore, the tandem duplicated SlASMT genes showed differential expression levels, which indicated probable functional divergence during the course of the evolution. Finally, this study also determined that some SlASMT genes were induced by multiple pathogens. The results suggested that these genes could be involved in tomato plant response to biotic stresses.

Genome-wide identification and characterization of GRAS transcription factors in tomato (Solanum lycopersicum).

Solanum lycopersicum, belonging to Solanaceae, is one of the commonly used model plants. The GRAS genes are transcriptional regulators, which play a significant role in plant growth and development, and the functions of several GRAS genes have been recognized, such as, axillary shoot meristem formation, radial root patterning, phytohormones (gibberellins) signal transduction, light signaling, and abiotic/biotic stress; however, only a few of these were identified and functionally characterized. In this study, a gene family was analyzed comprehensively with respect to phylogeny, gene structure, chromosomal localization, and expression pattern; the 54 GRAS members were screened from tomato by bioinformatics for the first time. The GRAS genes among tomato, Arabidopsis, rice, and grapevine were rebuilt to form a phylogenomic tree, which was divided into ten groups according to the previous classification of Arabidopsis and rice. A multiple sequence alignment exhibited the typical GRAS domain and conserved motifs similar to other gene families. Both the segmental and tandem duplications contributed significantly to the expansion and evolution of the GRAS gene family in tomato; the expression patterns across a variety of tissues and biotic conditions revealed potentially different functions of GRAS genes in tomato development and stress responses. Altogether, this study provides valuable information and robust candidate genes for future functional analysis for improving the resistance of tomato growth.

Genome-wide identification and expression analysis of glutathione S-transferase gene family in tomato: Gaining an insight to their physiological and stress-specific roles.

Glutathione S-transferase (GST) refers to one of the major detoxifying enzymes that plays an important role in different abiotic and biotic stress modulation pathways of plant. The present study aimed to a comprehensive genome-wide functional characterization of GST genes and proteins in tomato (Solanum lycopersicum L.). The whole genome sequence analysis revealed the presence of 90 GST genes in tomato, the largest GST gene family reported till date. Eight segmental duplicated gene pairs might contribute significantly to the expansion of SlGST gene family. Based on phylogenetic analysis of tomato, rice, and Arabidopsis GST proteins, GST family members could be further divided into ten classes. Members of each orthologous class showed high conservancy among themselves. Tau and lambda are the major classes of tomato; while tau and phi are the major classes for rice and Arabidopsis. Chromosomal localization revealed highly uneven distribution of SlGST genes in 13 different chromosomes, where chromosome 9 possessed the highest number of genes. Based on publicly available microarray data, expression analysis of 30 available SlGST genes exhibited a differential pattern in all the analyzed tissues and developmental stages. Moreover, most of the members showed highly induced expression in response to multiple biotic and abiotic stress inducers that could be harmonized with the increase in total GST enzyme activity under several stress conditions. Activity of tomato GST could be enhanced further by using some positive modulators (safeners) that have been predicted through molecular docking of SlGSTU5 and ligands. Moreover, tomato GST proteins are predicted to interact with a lot of other glutathione synthesizing and utilizing enzymes such as glutathione peroxidase, glutathione reductase, glutathione synthetase and γ-glutamyltransferase. This comprehensive genome-wide analysis and expression profiling would provide a rational platform and possibility to explore the versatile role of GST genes in crop engineering.

Genome-wide analysis and expression profiling of zinc finger homeodomain (ZHD) family genes reveal likely roles in organ development and stress responses in tomato

BackgroundZinc finger homeodomain proteins (ZHD) constitute a plant-specific transcription factor family with a conserved DNA binding homeodomain and a zinc finger motif. Members of the ZHD protein family play important roles in plant growth, development, and stress responses. Genome-wide characterization of ZHD genes has been carried out in several model plants, including Arabidopsis thaliana and Oryza sativa, but not yet in tomato (Solanum lycopersicum).ResultsIn this study, we performed the first comprehensive genome-wide characterization and expression profiling of the ZHD gene family in tomato (Solanum lycopersicum). We identified 22 SlZHD genes and classified them into six subfamilies based on phylogeny. The SlZHD genes were generally conserved in each subfamily, with minor variations in gene structure and motif distribution. The 22 SlZHD genes were distributed on six of the 12 tomato chromosomes, with segmental duplication detected in four genes. Analysis of Ka/Ks ratios revealed that the duplicated genes are under negative or purifying selection. Comprehensive expression analysis revealed that the SlZHD genes are widely expressed in various tissues, with most genes preferentially expressed in flower buds compared to other tissues. Moreover, many of the genes are responsive to abiotic stress and phytohormone treatment.ConclusionSystematic analysis revealed structural diversity among tomato ZHD proteins, which indicates the possibility for diverse roles of SlZHD genes in different developmental stages as well as in response to abiotic stresses. Our expression analysis of SlZHD genes in various tissues/organs and under various abiotic stress and phytohormone treatments sheds light on their functional divergence. Our findings represent a valuable resource for further analysis to explore the biological functions of tomato ZHD genes.

Genome-wide identification and expression analysis of the BTB domain-containing protein gene family in tomato.

BTB (broad-complex, tramtrack, and bric-a-brac) family proteins are characterized by the presence of a protein-protein interaction BTB domain. BTB proteins have diverse functions, including transcriptional regulation, protein degradation, chromatin remodeling, and cytoskeletal regulation. However, little is known about this gene family in tomato (Solanum lycopersicum), the most important model plant for crop species. In this study, 38 BTB genes were identified based on tomato whole-genome sequence. Phylogenetic analysis of BTB proteins in tomato revealed that SlBTB proteins could be divided into at least 4 subfamilies. The SlBTB proteins contains 1-3 BTB domains, and several other types of functional domains, including KCTD (Potassium channel tetramerization domain-containing), the MATH (meprin and TRAF homology), ANK (Ankyrin repeats), NPR1 (nonexpressor of pathogenesis-related proteins1), NPH3 (Nonphototropic Hypocotyl 3), TAZ zinc finger, C-terminal Kelch, Skp1 and Arm (Armadillo/beta-catenin-like repeat) domains are also found in some tomato BTB proteins. Moreover, their expression patterns in tissues/stages, in response to different abiotic stress treatments and hormones were also investigated. This study provides the first comprehensive analysis of BTB gene family in the tomato genome. The data will undoubtedly be useful for better understanding the potential functions of BTB genes, and their possible roles in mediating hormone cross-talk and abiotic stress in tomato as well as in some other relative species.

Molecular Characterization and Expression Profiling of Tomato GRF Transcription Factor Family Genes in Response to Abiotic Stresses and Phytohormones.

Growth regulating factors (GRFs) are plant-specific transcription factors that are involved in diverse biological and physiological processes, such as growth, development and stress and hormone responses. However, the roles of GRFs in vegetative and reproductive growth, development and stress responses in tomato (Solanum lycopersicum) have not been extensively explored. In this study, we characterized the 13 SlGRF genes. In silico analysis of protein motif organization, intron–exon distribution, and phylogenetic classification confirmed the presence of GRF proteins in tomato. The tissue-specific expression analysis revealed that most of the SlGRF genes were preferentially expressed in young and growing tissues such as flower buds and meristems, suggesting that SlGRFs are important during growth and development of these tissues. Some of the SlGRF genes were preferentially expressed in fruits at distinct developmental stages suggesting their involvement in fruit development and the ripening process. The strong and differential expression of different SlGRFs under NaCl, drought, heat, cold, abscisic acid (ABA), and jasmonic acid (JA) treatment, predict possible functions for these genes in stress responses in addition to their growth regulatory functions. Further, differential expression of SlGRF genes upon gibberellic acid (GA3) treatment indicates their probable function in flower development and stress responses through a gibberellic acid (GA)-mediated pathway. The results of this study provide a basis for further functional analysis and characterization of this important gene family in tomato.

Genomic Organization, Phylogenetic and Expression Analysis of the B-BOX Gene Family in Tomato.

The B-BOX (BBX) proteins encode a class of zinc-finger transcription factors possessing one or two B-BOX domains and in some cases an additional CCT (CO, CO-like and TOC1) motif, which play important roles in regulating plant growth, development and stress response. Nevertheless, no systematic study of BBX genes has undertaken in tomato (Solanum lycopersicum). Here we present the results of a genome-wide analysis of the 29 BBX genes in this important vegetable species. Their structures, conserved domains, phylogenetic relationships, subcellular localizations, and promoter cis-regulatory elements were analyzed; their tissue expression profiles and expression patterns under various hormones and stress treatments were also investigated in detail. Tomato BBX genes can be divided into five subfamilies, and twelve of them were found to be segmentally duplicated. Real-time quantitative PCR analysis showed that most BBX genes exhibited different temporal and spatial expression patterns. The expression of most BBX genes can be induced by drought, polyethylene glycol-6000 or heat stress. Some BBX genes were induced strongly by phytohormones such as abscisic acid, gibberellic acid, or ethephon. The majority of tomato BBX proteins was predicted to be located in nuclei, and the transient expression assay using Arabidopsis mesophyll protoplasts demonstrated that all the seven BBX members tested (SlBBX5, 7, 15, 17, 20, 22, and 24) were localized in nucleus. Our analysis of tomato BBX genes on the genome scale would provide valuable information for future functional characterization of specific genes in this family.

Identification and analysis of the metacaspase gene family in tomato

Metacaspases play critical roles in developmentally regulated and environmentally induced programmed cell death in plants. In this study, we systematically identified and analyzed metacaspase gene family in tomato (Solanum lycopersicum). The results illustrated that tomato possesses eight metacaspase genes (SlMC1−8) located on chromosomes 1, 3, 5, 9, and 10. SlMC1−6 belonged to type I metacaspases and had 5 exon/4 intron structures. SlMC7 and 8 were type II metacaspases and had 2 and 3 exons, respectively. Expression analysis revealed distinct expression patterns of SlMCs in various tomato tissues. Cis-regulatory element prediction showed that there were many hormone- and stress-related cis-regulatory elements in SlMCs promoter regions. Quantitative real-time PCR analysis further demonstrated that most of the SlMCs were regulated by drought, cold, salt, methyl viologen, and ethephon treatments. This study provides insights into the characteristics of SlMC genes and laid the foundation for further functional analysis of these genes in tomato.

The SOD Gene Family in Tomato: Identification, Phylogenetic Relationships, and Expression Patterns.

Superoxide dismutases (SODs) are critical antioxidant enzymes that protect organisms from reactive oxygen species (ROS) caused by adverse conditions, and have been widely found in the cytoplasm, chloroplasts, and mitochondria of eukaryotic and prokaryotic cells. Tomato (Solanum lycopersicum L.) is an important economic crop and is cultivated worldwide. However, abiotic and biotic stresses severely hinder growth and development of the plant, which affects the production and quality of the crop. To reveal the potential roles of SOD genes under various stresses, we performed a systematic analysis of the tomato SOD gene family and analyzed the expression patterns of SlSOD genes in response to abiotic stresses at the whole-genome level. The characteristics of the SlSOD gene family were determined by analyzing gene structure, conserved motifs, chromosomal distribution, phylogenetic relationships, and expression patterns. We determined that there are at least nine SOD genes in tomato, including four Cu/ZnSODs, three FeSODs, and one MnSOD, and they are unevenly distributed on 12 chromosomes. Phylogenetic analyses of SOD genes from tomato and other plant species were separated into two groups with a high bootstrap value, indicating that these SOD genes were present before the monocot-dicot split. Additionally, many cis-elements that respond to different stresses were found in the promoters of nine SlSOD genes. Gene expression analysis based on RNA-seq data showed that most genes were expressed in all tested tissues, with the exception of SlSOD6 and SlSOD8, which were only expressed in young fruits. Microarray data analysis showed that most members of the SlSOD gene family were altered under salt- and drought-stress conditions. This genome-wide analysis of SlSOD genes helps to clarify the function of SlSOD genes under different stress conditions and provides information to aid in further understanding the evolutionary relationships of SOD genes in plants.

Genome-Wide Identification and Expression Profiling of Tomato Hsp20 Gene Family in Response to Biotic and Abiotic Stresses.

The Hsp20 genes are involved in the response of plants to environment stresses including heat shock and also play a vital role in plant growth and development. They represent the most abundant small heat shock proteins (sHsps) in plants, but little is known about this family in tomato (Solanum lycopersicum), an important vegetable crop in the world. Here, we characterized heat shock protein 20 (SlHsp20) gene family in tomato through integration of gene structure, chromosome location, phylogenetic relationship, and expression profile. Using bioinformatics-based methods, we identified at least 42 putative SlHsp20 genes in tomato. Sequence analysis revealed that most of SlHsp20 genes possessed no intron or a relatively short intron in length. Chromosome mapping indicated that inter-arm and intra-chromosome duplication events contributed remarkably to the expansion of SlHsp20 genes. Phylogentic tree of Hsp20 genes from tomato and other plant species revealed that SlHsp20 genes were grouped into 13 subfamilies, indicating that these genes may have a common ancestor that generated diverse subfamilies prior to the mono-dicot split. In addition, expression analysis using RNA-seq in various tissues and developmental stages of cultivated tomato and the wild relative Solanum pimpinellifolium revealed that most of these genes (83%) were expressed in at least one stage from at least one genotype. Out of 42 genes, 4 genes were expressed constitutively in almost all the tissues analyzed, implying that these genes might have specific housekeeping function in tomato cell under normal growth conditions. Two SlHsp20 genes displayed differential expression levels between cultivated tomato and S. pimpinellifolium in vegetative (leaf and root) and reproductive organs (floral bud and flower), suggesting inter-species diversification for functional specialization during the process of domestication. Based on genome-wide microarray analysis, we showed that the transcript levels of SlHsp20 genes could be induced profusely by abiotic and biotic stresses such as heat, drought, salt, Botrytis cinerea, and Tomato Spotted Wilt Virus (TSWV), indicating their potential roles in mediating the response of tomato plants to environment stresses. In conclusion, these results provide valuable information for elucidating the evolutionary relationship of Hsp20 gene family and functional characterization of the SlHsp20 gene family in the future.

Genome-Wide Identification and Expression Analysis of Calcium-dependent Protein Kinase in Tomato.

Calcium-dependent protein kinases (CDPKs) play critical roles in regulating growth, development and stress response in plants. Information about CDPKs in tomato, however, remains obscure although it is one of the most important model crops in the world. In this study, we performed a bioinformatics analysis of the entire tomato genome and identified 29 CDPK genes. These CDPK genes are found to be located in 12 chromosomes, and could be divided into four groups. Analysis of the gene structure and splicing site reflected high structure conservation within different CDPK gene groups both in the exon-intron pattern and mRNA splicing. Transcripts of most CDPK genes varied with plant organs and developmental stages and their transcripts could be differentially induced by abscisic acid (ABA), brassinosteroids (BRs), methyl jasmonate (MeJA), and salicylic acid (SA), as well as after exposure to heat, cold, and drought, respectively. To our knowledge, this is the first report about the genome-wide analysis of the CDPK gene family in tomato, and the findings obtained offer a clue to the elaborated regulatory role of CDPKs in plant growth, development and stress response in tomato.

Genome-wide identification and expression profiling analysis of trihelix gene family in tomato

The trihelix family, classified as GT factors due to their binding specificity for GT elements, constitutes a plant-specific transcription factor family with a conserved trihelix DNA binding domain. In the present study, the comprehensive analysis of 36 putative GT factors was performed in tomato. SlGT members can be classified into six subgroups (GT-1, GT-2, SH4, SIP1, GT-γ and GT-δ). Expression analysis of SlGT gene transcripts showed the distinct expression patterns of SlGT genes in various tomato organs. All the SlGT genes were regulated in response to various abiotic stresses and hormone treatments by the quantitative real-time PCR (qRT-PCR) analysis. Several SlGT genes, including SlGT-27 and SlGT-34, were highly regulated by multiple abiotic stresses and phytohormone treatments. Taken together, our results presented here would be providing a useful platform for molecular clone and functional identification of SlGT genes in tomato.

Genome-wide identification and expression analysis of the expansin gene family in tomato.

Plant expansins are capable of inducing pH-dependent cell wall extension and stress relaxation. They may be useful as targets for crop improvement to enhance fruit development and stress resistance. Tomato is a major agricultural crop and a model plant for studying fruit development. Because only some tomato expansins have been studied, a genome-wide analysis of the tomato expansin family is necessary. In this study, we identified 25 SlEXPAs, eight SlEXPBs, one SlEXLA, four SlEXLBs, and five short homologs in the tomato genome. 25 of these genes were identified as being expressed. Bioinformatic analysis showed that although tomato expansins share similarities with those from other plants, they also exhibit specific features regarding genetic structure and amino acid sequences, which indicates a unique evolutionary process. Segmental and tandem duplication events have played important roles in expanding the tomato expansin family. Additionally, the 3-exon/2-intron structure may form the basic organization of expansin genes. We identified new expansin genes preferentially expressed in fruits (SlEXPA8, SlEXPB8, and SlEXLB1), roots (SlEXPA9, SlEXLB2, and SlEXLB4), and floral organs. Among the analyzed genes those that were inducible by hormone or stress treatments, including SlEXPA3, SlEXPA7, SlEXPB1-B2, SlEXPB8, SlEXLB1-LB2, and SlEXLB4. Our findings may further clarify the biological activities of tomato expansins, especially those related to fruit development and stress resistance, and contribute to the genetic modification of tomato plants to improve crop quality and yield.

Genome-wide identification, phylogeny and expression analysis of GRAS gene family in tomato.

BackgroundGRAS transcription factors usually act as integrators of multiple growth regulatory and environmental signals, including axillary shoot meristem formation, root radial pattering, phytohormones, light signaling, and abiotic/biotic stress. However, little is known about this gene family in tomato (Solanum lycopersicum), the most important model plant for crop species with fleshy fruits.ResultsIn this study, 53 GRAS genes were identified and renamed based on tomato whole-genome sequence and their respective chromosome distribution except 19 members were kept as their already existed name. Multiple sequence alignment showed typical GRAS domain in these proteins. Phylogenetic analysis of GRAS proteins from tomato, Arabidopsis, Populus, P.mume, and Rice revealed that SlGRAS proteins could be divided into at least 13 subfamilies. SlGRAS24 and SlGRAS40 were identified as target genes of miR171 using5’-RACE (Rapid amplification of cDNA ends). qRT-PCR analysis revealed tissue-/organ- and development stage-specific expression patterns of SlGRAS genes. Moreover, their expression patterns in response to different hormone and abiotic stress treatments were also investigated.ConclusionsThis study provides the first comprehensive analysis of GRAS gene family in the tomato genome. The data will undoubtedly be useful for better understanding the potential functions of GRAS genes, and their possible roles in mediating hormone cross-talk and abiotic stress in tomato as well as in some other relative species.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0590-6) contains supplementary material, which is available to authorized users.

Genome-wide identification, phylogeny, and expression analysis of the SWEET gene family in tomato

The SWEET (Sugars Will Eventually Be Exported Transporters) gene family encodes membrane-embedded sugar transporters containing seven transmembrane helices harboring two MtN3 and saliva domain. SWEETs play important roles in diverse biological processes, including plant growth, development, and response to environmental stimuli. Here, we conducted an exhaustive search of the tomato genome, leading to the identification of 29 SWEET genes. We analyzed the structures, conserved domains, and phylogenetic relationships of these protein-coding genes in detail. We also analyzed the transcript levels of SWEET genes in various tissues, organs, and developmental stages to obtain information about their functions. Furthermore, we investigated the expression patterns of the SWEET genes in response to exogenous sugar and adverse environmental stress (high and low temperatures). Some family members exhibited tissue-specific expression, whereas others were more ubiquitously expressed. Numerous stress-responsive candidate genes were obtained. The results of this study provide insights into the characteristics of the SWEET genes in tomato and may serve as a basis for further functional studies of such genes.

Cyclic nucleotide gated channel gene family in tomato: genome-wide identification and functional analyses in disease resistance.

The cyclic nucleotide gated channel (CNGC) is suggested to be one of the important calcium conducting channels. Nevertheless, genome-wide identification and systemic functional analysis of CNGC gene family in crop plant species have not yet been conducted. In this study, we performed genome-wide identification of CNGC gene family in the economically important crop tomato (Solanum lycopersicum L.) and analyzed function of the group IVb SlCNGC genes in disease resistance. Eighteen CNGC genes were identified in tomato genome, and four CNGC loci that were misannotated at database were corrected by cloning and sequencing. Detailed bioinformatics analyses on gene structure, domain composition and phylogenetic relationship of the SlCNGC gene family were conducted and the group-specific feature was revealed. Comprehensive expression analyses demonstrated that SlCNGC genes were highly, widely but differently responsive to diverse stimuli. Pharmacological assays showed that the putative CNGC activators cGMP and cAMP enhanced resistance against Sclerotinia sclerotiorum. Silencing of group IVb SlCNGC genes significantly enhanced resistance to fungal pathogens Pythium aphanidermatum and S. sclerotiorum, strongly reduced resistance to viral pathogen Tobacco rattle virus, while attenuated PAMP- and DAMP-triggered immunity as shown by obvious decrease of the flg22- and AtPep1-elicited hydrogen peroxide accumulation in SlCNGC-silenced plants. Additionally, silencing of these SlCNGC genes significantly altered expression of a set of Ca2+ signaling genes including SlCaMs, SlCDPKs, and SlCAMTA3. Collectively, our results reveal that group IV SlCNGC genes regulate a wide range of resistance in tomato probably by affecting Ca2+ signaling.

Genome-wide identification and characterization of the bHLH gene family in tomato.

BackgroundThe basic helix-loop-helix (bHLH) proteins are a large superfamily of transcription factors, and play a central role in a wide range of metabolic, physiological, and developmental processes in higher organisms. Tomato is an important vegetable crop, and its genome sequence has been published recently. However, the bHLH gene family of tomato has not been systematically identified and characterized yet.ResultsIn this study, we identified 159 bHLH protein-encoding genes (SlbHLH) in tomato genome and analyzed their structures. Although bHLH domains were conserved among the bHLH proteins between tomato and Arabidopsis, the intron sequences and distribution of tomato bHLH genes were extremely different compared with Arabidopsis. The gene duplication analysis showed that 58.5% and 6.3% of SlbHLH genes belonged to low-stringency and high-stringency duplication, respectively, indicating that the SlbHLH genes are mainly generated via short low-stringency region duplication in tomato. Subsequently, we classified the SlbHLH genes into 21 subfamilies by phylogenetic tree analysis, and predicted their possible functions by comparison with their homologous genes of Arabidopsis. Moreover, the expression profile analysis of SlbHLH genes from 10 different tissues showed that 21 SlbHLH genes exhibited tissue-specific expression. Further, we identified that 11 SlbHLH genes were associated with fruit development and ripening (eight of them associated with young fruit development and three with fruit ripening). The evolutionary analysis revealed that 92% SlbHLH genes might be evolved from ancestor(s) originated from early land plant, and 8% from algae.ConclusionsIn this work, we systematically identified SlbHLHs by analyzing the tomato genome sequence using a set of bioinformatics approaches, and characterized their chromosomal distribution, gene structures, duplication, phylogenetic relationship and expression profiles, as well predicted their possible biological functions via comparative analysis with bHLHs of Arabidopsis. The results and information provide a good basis for further investigation of the biological functions and evolution of tomato bHLH genes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-014-1209-2) contains supplementary material, which is available to authorized users.

Genome-wide characterization, expression and functional analysis of CLV3/ESR gene family in tomato.

BackgroundBy encoding a group of small secretory peptides, the members of the CLAVATA3/EMBRYO-SURROUNDING REGION (CLE) family play important roles in cell-to-cell communication to control the balance between stem cell proliferation and differentiation in plant development. Despite recent identification and characterization of members of this gene family in several plant species, little is known about its functional role in plants with fleshy fruits.ResultsIn total, fifteen CLE genes (SlCLE1-15) were identified from tomato (Solanum lycopersicum cv. ‘Heinz-1706’) genome and their multiple characters including phylogeny, gene structures, chromosome locations, conserved motifs and cis-elements in the promoter sequences, were analyzed. Real-time PCR analysis showed that 13 out of 15 identified SlCLE genes are transcribed and exhibit remarkably unique expression patterns among tissues and organs. In particular, SlCLE12, the homologue of Arabidopsis CLE41/44 gene, appears to be the dominant CLE gene in most of tested tissues with its maximum expression found in vascular tissues. Meanwhile, SlCLE1, 10, 13 exhibit specific but distinct expression in flower bud, root and shoot apex, respectively. More notably, several SlCLEs are dramatically regulated in their transcriptional levels during fruit development and ripening, indicating significant role these genes may potentially play in the critical physiological process. Upon the treatment with synthetic peptides corresponding to the 12-aa CLE domains of SlCLE 10, 12 and 13, tomato seedlings exhibit a clear reduction in root length to varying degrees.ConclusionsThis study provides a comprehensive genomic analysis of CLE gene family in tomato, a crop species with fleshy fruit. Differential expression patterns of various SlCLEs provide important insights into the functional divergence of CLE signaling cascade in Solanaceae species, especially their potential involvements in the regulation of fruit development and ripening.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-827) contains supplementary material, which is available to authorized users.