B-box Gene Research Articles

Genome-wide identification, molecular evolution and expression analysis of the B-box gene family in mung bean (Vigna radiata L.)

BackgroundMung bean (Vigna radiata L.) is an important warm-season grain legume. Adaptation to extreme environmental conditions, supported by evolution, makes mung bean a rich gene pool for stress tolerance traits. The exploration of resistance genes will provide important genetic resources and a theoretical basis for strengthening mung bean breeding. B-box (BBX) proteins play a major role in developmental processes and stress responses. However, the identification and analysis of the mung bean BBX gene family are still lacking.ResultsIn this study, 23 VrBBX genes were identified through comprehensive bioinformatics analysis and named based on their physical locations on chromosomes. All the VrBBXs were divided into five groups based on their phylogenetic relationships, the number of B-box they contained and whether there was an additional CONSTANS, CO-like and TOC1 (CCT) domain. Homology and collinearity analysis indicated that the BBX genes in mung bean and other species had undergone a relatively conservative evolution. Gene duplication analysis showed that only chromosomal segmental duplication contributed to the expansion of VrBBX genes and that most of the duplicated gene pairs experienced purifying selection pressure during evolution. Gene structure and motif analysis revealed that VrBBX genes clustered in the same group shared similar structural characteristics. An analysis of cis-acting elements indicated that elements related to stress and hormone responses were prevalent in the promoters of most VrBBXs. The RNA-seq data analysis and qRT-PCR of nine VrBBX genes demonstrated that VrBBX genes may play a role in response to environmental stress. Moreover, VrBBX5, VrBBX10 and VrBBX12 are important candidate genes for plant stress response.ConclusionsIn this study, we systematically analyzed the genomic characteristics and expression patterns of the BBX gene family under ABA, PEG and NaCl treatments. The results will help us better understand the complexity of the BBX gene family and provide valuable information for future functional characteristics of specific genes in this family.

Genome-Wide Identification of Peanut B-Boxs and Functional Characterization of AhBBX6 in Salt and Drought Stresses.

The B-box (BBX) gene family includes zinc finger protein transcription factors that regulate a multitude of physiological and developmental processes in plants. While BBX gene families have been previously determined in various plants, the members and roles of peanut BBXs are largely unknown. In this research, on the basis of the genome-wide identification of BBXs in three peanut species (Arachis hypogaea, A. duranensis, and A. ipaensis), we investigated the expression profile of the BBXs in various tissues and in response to salt and drought stresses and selected AhBBX6 for functional characterization. We identified a total of 77 BBXs in peanuts, which could be grouped into five subfamilies, with the genes from the same branch of the same subgroup having comparable exon-intron structures. In addition, a significant number of cis-regulatory elements involved in the regulation of responses to light and hormones and abiotic stresses were found in the promoter region of peanut BBXs. Based on the analysis of transcriptome data and qRT-PCR, we identified AhBBX6, AhBBX11, AhBBX13, and AhBBX38 as potential genes associated with tolerance to salt and drought. Silencing AhBBX6 using virus-induced gene silencing compromised the tolerance of peanut plants to salt and drought stresses. The results of this study provide knowledge on peanut BBXs and establish a foundation for future research into their functional roles in peanut development and stress response.

Genome-Wide Identification of B-Box Gene Family and Candidate Light-Related Member Analysis of Tung Tree (Vernicia fordii).

Light is one of the most important environmental factors for plant growth. In the production process of tung oil tree cultivation, due to the inappropriate growth of shading conditions, the lower branches are often dry and dead, which seriously affects the yield of tung oil trees. However, little is known about the key factors of light-induced tree photomorphogenesis. In this study, a total of 22 VfBBX family members were identified to provide a reference for candidate genes in tung tree seedlings. All members of the VfBBX family have different numbers of highly conserved B-box domains or CCT domains. Phylogenetic evolution clustered the VfBBX genes into four categories, and the highest density of members was on chromosome 6. Interspecific collinearity analysis suggested that there were six pairs of duplicate genes in VfBBX members, but the expression levels of all family members in different growth and development stages of the tung tree were significantly divergent. After different degrees of shading treatment and physiological data determination of tung tree seedlings, the differential expression level and chlorophyll synthesis genes correlation analysis revealed that VfBBX9 was a typical candidate nuclear localization transcription factor that was significantly differentially expressed in light response. This study systematically identified the VfBBX gene family and provided a reference for studying its molecular function, enhanced the theoretical basis for tung tree breeding, and identified excellent varieties.

Genome-wide characterization of tobacco B-BOX gene family identified two close members play contrast roles under cold stress

Cold stress influences the growth and geographical distribution of plants. Tobacco (Nicotiana tabacum L.), a model in plant biology studies and a world-widely cultivated economic plant from tropical America, exhibits extreme sensitivity to low temperatures. The conserved B-BOX (BBX) transcription factors play vital roles in plant photomorphogenesis and flowering regulation, and their functions in abiotic stresses, including cold stress, have been uncovered recently. However, few studies on tobacco BBX genes have been conducted to date. In this study, 49 non-redundant BBX genes have been identified in the reference tobacco genome. Gene structure, phylogenetic relationship, prediction of cis-regulatory elements in promoters, tissue-specific expression patterns, and response to cold stress were conducted on these BBX gene members. The expression of NtBBX9 and NtBBX11, two close members in the amplified group II, was up-regulated under cold treatments. Overexpression of NtBBX11 embedded the cold tolerance of transgenic plants, while the NtBBX9 overexpressors were susceptible to cold. The NtBBX9 functions as a negative regulator of tobacco response to cold stress, which was confirmed by the phenotype of NtBBX9 RNA-silenced lines. Furthermore, we demonstrated that NtBBX9 and NtBBX11 regulated the cold stress response by alternating the expression of critical cold-regulated genes such as CBFs, LEA14, and LTI65 and reactive oxygen species (ROS) production. The combination of NtBBX9 and NtBBX11 could facilitate tobacco’s rapid response to and recovery from transient cold stress and regulate plant cold-responsive growth in tropical regions.

Identification and Characterization of the BBX Gene Family in Bambusa pervariabilis × Dendrocalamopsis grandis and Their Potential Role under Adverse Environmental Stresses.

Zinc finger protein (ZFP) transcription factors play a pivotal role in regulating plant growth, development, and response to biotic and abiotic stresses. Although extensively characterized in model organisms, these genes have yet to be reported in bamboo plants, and their expression information is lacking. Therefore, we identified 21 B-box (BBX) genes from a transcriptome analysis of Bambusa pervariabilis × Dendrocalamopsis grandis. Consequently, multiple sequence alignments and an analysis of conserved motifs showed that they all had highly similar structures. The BBX genes were divided into four subgroups according to their phylogenetic relationships and conserved domains. A GO analysis predicted multiple functions of the BBX genes in photomorphogenesis, metabolic processes, and biological regulation. We assessed the expression profiles of 21 BBX genes via qRT-PCR under different adversity conditions. Among them, eight genes were significantly up-regulated under water deficit stress (BBX4, BBX10, BBX11, BBX14, BBX15, BBX16, BBX17, and BBX21), nine under salt stress (BBX2, BBX3, BBX7, BBX9, BBX10, BBX12, BBX15, BBX16, and BBX21), twelve under cold stress (BBX1, BBX2, BBX4, BBX7, BBX10, BBX12, BBX14, BBX15, BBX17, BBX18, BBX19, and BBX21), and twelve under pathogen infestation stress (BBX1, BBX2, BBX4, BBX7, BBX10, BBX12, BBX14, BBX15, BBX17, BBX18, BBX19, and BBX21). Three genes (BBX10, BBX15, and BBX21) were significantly up-regulated under both biotic and abiotic stresses. These results suggest that the BBX gene family is integral to plant growth, development, and response to multivariate stresses. In conclusion, we have comprehensively analyzed the BDBBX genes under various adversity stress conditions, thus providing valuable information for further functional studies of this gene family.

Genome-Wide Identification of B-Box Gene Family and Expression Analysis Suggest Its Roles in Responses to Cercospora Leaf Spot in Sugar Beet (Beta Vulgaris L.).

The B-box (BBX) protein, which is a zinc-finger protein containing one or two B-box domains, plays a crucial role in the growth and development of plants. Plant B-box genes are generally involved in morphogenesis, the growth of floral organs, and various life activities in response to stress. In this study, the sugar beet B-box genes (hereafter referred to as BvBBXs) were identified by searching the homologous sequences of the Arabidopsis thaliana B-box gene family. The gene structure, protein physicochemical properties, and phylogenetic analysis of these genes were systematically analyzed. In this study, 17 B-box gene family members were identified from the sugar beet genome. A B-box domain can be found in all sugar beet BBX proteins. BvBBXs encode 135 to 517 amino acids with a theoretical isoelectric point of 4.12 to 6.70. Chromosome localization studies revealed that BvBBXs were dispersed across nine sugar beet chromosomes except chromosomes 5 and 7. The sugar beet BBX gene family was divided into five subfamilies using phylogenetic analysis. The gene architectures of subfamily members on the same evolutionary tree branch are quite similar. Light, hormonal, and stress-related cis-acting elements can be found in the promoter region of BvBBXs. The BvBBX gene family was differently expressed in sugar beet following Cercospora leaf spot infection, according to RT-qPCR data. It is shown that the BvBBX gene family may influence how the plant reacts to a pathogen infection.

Genome-wide identification and analysis of B-box zinc finger gene family in sugarcane (Saccharum officinarum)

Objective and methodsB-box-containing proteins are a kind of zinc finger (ZF) transcript protein that contains 1 otherwise 2 B-box domains even, in some cases, an additional CCT motif that is crucial for plant growth development and controlling biotic and abiotic stress. There has yet to be a comprehensive identification of the BBX genes in sugarcane by using bioinformatics tools/softwares. ResultsConsidered in the present research work, 21 Sugarcane genes were discovered by comprehensive bioinformatics analysis viz the phylogeny relationships, structures of genes, locations of chromosomes, gene duplication, subcellular localization, homology and codon analysis were analysed. Relying on phylogeny as well as domain constitution analysis, the identified genes must be divided into five clades. Eight out of ten Sugarcane chromosomes had an uneven distribution of Shbbxs. The significant proportion of sugarcane BBX proteins are expected to be found in nuclei and extracellular spaces. ConclusionOur findings will serve as a foundation for subsequent functional findings of the BBX gene family, highlighting its roles in sugarcane. The findings will aid our understanding in the B-box gene family's complexity towards the abiotic stress responses, as well as provide suggestions for the imminent functional annotation of specific genes in sugarcane.

Genome-wide Identification of the Upland Cotton (Gossypium hirsutum L.) B-BOX gene Family and its Expression After Drought Stress

Genome-wide Identification of the Upland Cotton (Gossypium hirsutum L.) B-BOX gene Family and its Expression After Drought Stress

Genome-Wide Analysis of the BBX Genes in Platanus × acerifolia and Their Relationship with Flowering and/or Dormancy.

The B-BOX (BBX) gene family is widely distributed in animals and plants and is involved in the regulation of their growth and development. In plants, BBX genes play important roles in hormone signaling, biotic and abiotic stress, light-regulated photomorphogenesis, flowering, shade response, and pigment accumulation. However, there has been no systematic analysis of the BBX family in Platanus × acerifolia. In this study, we identified 39 BBX genes from the P. × acerifolia genome, and used TBtools, MEGA, MEME, NCBI CCD, PLANTCARE and other tools for gene collinearity analysis, phylogenetic analysis, gene structure, conserved domain analysis, and promoter cis-element analysis, and used the qRT-PCR and transcriptome data for analyzing expression pattern of the PaBBX genes. Collinearity analysis indicated segmental duplication was the main driver of the BBX family in P. × acerifolia, and phylogenetic analysis showed that the PaBBX family was divided into five subfamilies: I, II, III, IV and V. Gene structure analysis showed that some PaBBX genes contained super-long introns that may regulate their own expression. Moreover, the promoter of PaBBX genes contained a significant number of cis-acting elements that are associated with plant growth and development, as well as hormone and stress responses. The qRT-PCR results and transcriptome data indicated that certain PaBBX genes exhibited tissue-specific and stage-specific expression patterns, suggesting that these genes may have distinct regulatory roles in P. × acerifolia growth and development. In addition, some PaBBX genes were regularly expressed during the annual growth of P. × acerifolia, corresponding to different stages of flower transition, dormancy, and bud break, indicating that these genes may be involved in the regulation of flowering and/or dormancy of P. × acerifolia. This article provided new ideas for the study of dormancy regulation and annual growth patterns in perennial deciduous plants.

Genome-wide characterization of B-box gene family in Artemisia annua L. and its potential role in the regulation of artemisinin biosynthesis

Artemisinin is a sesquiterpene lactone synthesized by the Chinese medicinal plant Artemisia annua L., and is the principal component used for the treatment of malaria. Recent studies have demonstrated the potential role of B-box (BBX) transcription factors in regulating plant secondary metabolism. However, the roles and functions of BBX members in the biosynthesis of artemisinin in A. annua have not been reported yet. In this study, a total of 27 BBX members (AaBBXs) were identified and classified into five sub-groups (I-V). The AaBBXs in each sub-group shared similar gene structures, conserved domains and motifs. Additionally, multiple cis-acting elements which are responsible for light, hormones, and stress signals were found in the promoter regions of AaBBX members. Based on transcriptome data, 27 AaBBXs showed constitutive expression in different organs/tissues, while several BBX genes exhibited higher expression levels in glandular secretory trichomes (GSTs), the site of artemisinin biosynthesis. To explore the roles of AaBBX members in regulating the artemisinin biosynthesis, 7 AaBBXs (AaBBX5/6/8/15/22/23/24) were selected for further investigation. The expressions of all 7 selected AaBBXs were strongly induced by MeJA and ABA, and they were all found to be nuclear localized. Additionally, all seven proteins were found to have the ability to physically interact with AaJAZ8 in vitro. Dual-luciferase assays revealed that AaBBX5/6/8/15/22/23 can activate the promoter activity of the artemisinin biosynthetic pathway genes such as AaADS, AaCYP71AV1, AaDBR2 and AaALDH1 at different degrees. AaBBX22 showed highest expression level in A. annua GSTs, and can significantly activate the promoters of all four artemisinin biosynthetic pathway genes. Furthermore, transgenic assay results indicated that AaBBX22 acted as a positive regulator for the biosynthesis of artemisinin in A. annua. Taken together, this study provided a comprehensive genome-wide characterization of the BBX family and identified several significant BBX genes, including AaBBX22, which paves the way for further investigation into the regulatory role of the BBX gene family in artemisinin biosynthesis.

Characterization of the B-BOX gene family in pepper and the role of CaBBX14 in defense response against Phytophthora capsici infection

The B-box (BBX) transcription factors are widely implicated in plant growth, development, and response to various biotic and abiotic stresses. However, their roles in the response of pepper to Phytophthora capsici infection (PCI) remain largely unexplored. Here, we report a total of 25 CaBBX genes with an uneven distribution were identified in pepper genome, and their characteristics, phylogenetic relationships, gene structures, conserved domains, and expression profiles were validated. CaBBXs were classified into five major clades (I to V) based on their phylogenetic relationships and conserved domains (presence of one or two B­box domains and a CCT domain). Gene duplication analysis demonstrated that there are two segmental duplication events but no tandem duplication event within pepper genome. Conserved motif and gene structure analysis revealed that the CaBBXs in the same clade have relatively similar motif arrangements and exon-intron patterns. Expression analysis revealed that the CaBBX genes have different expression levels in various tissues, and some of which were significantly induced during PCI and exogenous salicylic acid (SA) treatment. Among them, CaBBX14 displayed remarkable changed expression during PCI and SA treatment. The silencing of CaBBX14 increases pepper susceptibility to PCI, and also decreases in SA content and expression of pathogenesis-related (PR) and SA-related genes compared with control plants. Together, these findings advance our knowledge base on biological functions of CaBBXs in pepper during PCI through the SA signaling pathway, and we provide an example demonstrating that the potential of CaBBX14 to improve pepper resistance to PCI.

Two B-box proteins, PavBBX6/9, positively regulate light-induced anthocyanin accumulation in sweet cherry.

Anthocyanin production in bicolored sweet cherry (Prunus avium cv. Rainier) fruit is induced by light exposure, leading to red coloration. The phytohormone abscisic acid (ABA) is essential for this process, but the regulatory relationships that link light and ABA with anthocyanin-associated coloration are currently unclear. In this study, we determined that light treatment of bicolored sweet cherry fruit increased anthocyanin accumulation and induced ABA production and that ABA participates in light-modulated anthocyanin accumulation in bicolored sweet cherry. Two B-box (BBX) genes, PavBBX6/9, were highly induced by light and ABA treatments, as was anthocyanin accumulation. The ectopic expression of PavBBX6 or PavBBX9 in Arabidopsis (Arabidopsis thaliana) increased anthocyanin biosynthesis and ABA accumulation. Overexpressing PavBBX6 or PavBBX9 in sweet cherry calli also enhanced light-induced anthocyanin biosynthesis and ABA accumulation. Additionally, transient overexpression of PavBBX6 or PavBBX9 in sweet cherry peel increased anthocyanin and ABA contents, whereas silencing either gene had the opposite effects. PavBBX6 and PavBBX9 directly bound to the G-box elements in the promoter of UDP glucose-flavonoid-3-O-glycosyltransferase (PavUFGT), a key gene for anthocyanin biosynthesis, and 9-cis-epoxycarotenoid dioxygenase 1 (PavNCED1), a key gene for ABA biosynthesis, and enhanced their activities. These results suggest that PavBBX6 and PavBBX9 positively regulate light-induced anthocyanin and ABA biosynthesis by promoting PavUFGT and PavNCED1 expression, respectively. Our study provides insights into the relationship between the light-induced ABA biosynthetic pathway and anthocyanin accumulation in bicolored sweet cherry fruit.

Characterization and expression profiles of the B-box gene family during plant growth and under low-nitrogen stress in Saccharum

BackgroundB-box (BBX) zinc-finger transcription factors play crucial roles in plant growth, development, and abiotic stress responses. Nevertheless, little information is available on sugarcane (Saccharum spp.) BBX genes and their expression profiles.ResultsIn the present study, we characterized 25 SsBBX genes in the Saccharum spontaneum genome database. The phylogenetic relationships, gene structures, and expression patterns of these genes during plant growth and under low-nitrogen conditions were systematically analyzed. The SsBBXs were divided into five groups based on phylogenetic analysis. The evolutionary analysis further revealed that whole-genome duplications or segmental duplications were the main driving force for the expansion of the SsBBX gene family. The expression data suggested that many BBX genes (e.g., SsBBX1 and SsBBX13) may be helpful in both plant growth and low-nitrogen stress tolerance.ConclusionsThe results of this study offer new evolutionary insight into the BBX family members in how sugarcane grows and responds to stress, which will facilitate their utilization in cultivated sugarcane breeding.

PpZAT5 suppresses the expression of a B-box gene PpBBX18 to inhibit anthocyanin biosynthesis in the fruit peel of red pear.

BBX (B-box) proteins play a vital role in light-induced anthocyanin biosynthesis. PpBBX18 was an indispensable regulator for the induction of anthocyanin biosynthesis in the peel of red pear fruit (Pyrus pyrifolia Nakai.). However, the upstream regulation of BBX genes has not been well characterized. In this study, PpZAT5, a cysteine2/histidine2-type transcription factor, was discovered as the upstream negative regulator of PpBBX18. The results showed that PpZAT5 functions as a transcriptional repressor and directly binds to the CAAT motif of PpBBX18 and inhibits its expression. PpZAT5 expression was inhibited by light, which is converse to the expression pattern of anthocyanin-related structural genes. In addition, less anthocyanin accumulated in the PpZAT5-overexpressing pear calli than in the wild-type pear calli; on the contrary, more anthocyanin accumulated in PpZAT5-RNAi pear calli. Moreover, the crucial genes involved in light-induced anthocyanin biosynthesis were markedly down-regulated in the transcriptome of PpZAT5 overexpression pear calli compared to wild-type. In conclusion, our study indicates that PpBBX18 is negatively regulated by a C2H2-type transcriptional repressor, PpZAT5, which reduces anthocyanin content in pear. The present results demonstrate an upstream molecular mechanism of PpBBX18 and provide insights into light-induced anthocyanin biosynthesis.

RETRACTED: Genome-wide analysis of the B-box gene family in the sweetpotato wild ancestor Ipomoea trifida and determination of the function of IbBBX28 in the regulation of flowering time of Arabidopsis

B-box (BBX) proteins constitute a class of transcription factors that play vital roles in the regulation of photoperiod flowering, photomorphogenesis, and the response to biotic and abiotic stresses. In this paper, a total of 32 BBX genes were identified in Ipomoea trifida, a wild ancestor of sweetpotato. Chromosome localization analysis showed that these 32 ItfBBX genes were distributed unevenly across 12 chromosomes. The ItfBBX gene family members were classified into five groups according to their phylogenetic relationships and structural features. Predictions of cis-elements revealed that the promoter sequences of the ItfBBX genes contain light response, stress response, hormone response and other elements. Synteny analysis revealed evidence of 26 segmental duplication events and only one tandem duplication event. Tissue-specific and abiotic stress-response expression profiles were analysed, and the results were confirmed via RT-qPCR. Overall, ItfBBX genes may play vital roles in the stress response. We chose IbBBX28 for further study and revealed that IbBBX28 negatively regulates the flowering time of IbBBX28-overexpressing Arabidopsis under long-day conditions. Our study provides references for characterizing the function of BBX genes in sweetpotato.

Genome-Wide Identification of the B-Box Gene Family and Expression Analysis Suggests Their Potential Role in Photoperiod-Mediated β-Carotene Accumulation in the Endocarp of Cucumber (Cucumis sativus L.) Fruit.

Carotenoids are indispensable to plants and essential for human nutrition and health. Carotenoid contents are strongly influenced by light through light-responsive genes such as B-Box (BBX) genes. BBX proteins, a class of zinc-finger transcription factors, mediate many light-signaling pathways, leading to the biosynthesis of important metabolites in plants. However, the identification of the BBX gene family and expression analysis in response to photoperiod-mediated carotenoid accumulation in cucumber remains unexplored. We performed a genome-wide study and determined the expression of cucumber BBX genes (hereafter referred to as CsaBBXs genes) in the endocarp of Xishuangbanna cucumber fruit (a special type of cucumber accumulating a high level of β-carotene in the endocarp) using an RNA-seq analysis of plants previously subjected to two photoperiodic conditions. Here, 26 BBX family genes were identified in the cucumber genome and named serially CsaBBX1 through CsaBBX26. We characterized CsaBBX genes in terms of their phylogenetic relationships, exon-intron structures, cis-acting elements, and syntenic relationships with Arabidopsis thaliana (L.) Heynh. RNA-seq analysis revealed a varied expression of CsaBBX genes under photoperiod treatment. The analysis of CsaBBXs genes revealed a strong positive correlation between CsaBBX17 and carotenoid biosynthetic pathway genes (phytoene synthase, ζ-carotene desaturase, lycopene ε-cyclase, β-carotene hydroxylase-1), thus suggesting its involvement in β-carotene biosynthesis. Additionally, nine CsaBBX genes (CsaBBX 4,5,7,9,11, 13,15,17 and 22) showed a significant positive correlation with β-carotene content. The selected CsaBBX genes were verified by qRT-PCR and confirmed the validity of RNA-seq data. The results of this study established the genome-wide analysis of the cucumber BBX family and provide a framework for understanding their biological role in carotenoid accumulation and photoperiodic responses. Further investigations of CsaBBX genes are vital since they are promising candidate genes for the functional analysis of carotenoid biosynthesis and can provide genetic tools for the molecular breeding of carotenoids in plants.

Genome-Wide Characterization and Anthocyanin-Related Expression Analysis of the B-BOX Gene Family in Capsicum annuum L.

The transcription factors, B-box (BBX), belong to a subfamily of the zinc finger family of proteins and exhibit multiple biological functions in plant growth, development, and abiotic stress response pathways. In this study, a total of 23 CaBBX members were identified using the pepper reference genome database. According to the gene structure, conserved domains, and the phylogenetic tree, 23 CaBBX genes were divided into four groups, wherein the analysis of the promoter region indicated the presence of cis-acting elements related to plant development, hormones, and stress response. Interspecies collinearity analysis showed that the CaBBXs had three duplicated gene pairs, and the highest gene density was found on chromosomes 2 and 7. Transcriptome RNA-seq data and quantitative polymerase chain reaction (qRT-PCR) analysis of pepper plants spanning the entire period showed that more than half of the CaBBX genes were widely expressed in diversity tissues of pepper. Co-expression network analysis indicated that the CaBBXs and the anthocyanin structural genes had a close co-expression relationship. Thus, it was reasonably speculated that the CaBBX genes may be involved in the regulation of anthocyanin biosynthesis. Overall, this study involved the genome-wide characterization of the CaBBX family and may serve as a solid foundation for further investigations on CaBBX genes involved in the anthocyanin synthesis mechanisms and development in pepper.

Genome-wide and expression analysis of B-box gene family in pepper

BackgroundBBX transcription factors are a kind of zinc finger transcription factors with one or two B-box domains, which partilant in plant growth, development and response to abiotic or biotic stress. The BBX family has been identified in Arabidopsis, rice, tomato and some other model plant genomes.ResultsHere, 24 CaBBX genes were identified in pepper (Capsicum annuum L.), and the phylogenic analysis, structures, chromosomal location, gene expression patterns and subcellular localizations were also carried out to understand the evolution and function of CaBBX genes. All these CaBBXs were divided into five classes, and 20 of them distributed in 11 of 12 pepper chromosomes unevenly. Most duplication events occurred in subgroup I. Quantitative RT-PCR indicated that several CaBBX genes were induced by abiotic stress and hormones, some had tissue-specific expression profiles or differentially expressed at developmental stages. Most of CaBBX members were predicated to be nucleus-localized in consistent with the transient expression assay by onion inner epidermis of the three tested CaBBX members (CaBBX5, 6 and 20).ConclusionSeveral CaBBX genes were induced by abiotic stress and exogenous phytohormones, some expressed tissue-specific and variously at different developmental stage. The detected CaBBXs act as nucleus-localized transcription factors. Our data might be a foundation in the identification of CaBBX genes, and a further understanding of their biological function in future studies.

Genome-Wide Identification, Evolution, and Comparative Analysis of B-Box Genes in Brassica rapa, B. oleracea, and B. napus and Their Expression Profiling in B. rapa in Response to Multiple Hormones and Abiotic Stresses.

The B-box zinc-finger transcription factors are important for plant growth, development, and various physiological processes such as photomorphogenesis, light signaling, and flowering, as well as for several biotic and abiotic stress responses. However, there is relatively little information available regarding Brassica B-box genes and their expression. In this study, we identified 51, 52, and 101 non-redundant genes encoding B-box proteins in Brassica rapa (BrBBX genes), B. oleracea (BoBBX genes), and B. napus (BnBBX genes), respectively. A whole-genome identification, characterization, and evolutionary analysis (synteny and orthology) of the B-box gene families in the diploid species B. rapa (A genome) and B. oleracea (C genome) and in the allotetraploid species B. napus (AC genome) revealed segmental duplications were the major contributors to the expansion of the Brassica BBX gene families. The Brassica BBX genes were classified into five subgroups according to phylogenetic relationships, gene structures, and conserved domains. Light-responsive cis-regulatory elements were detected in many of the BBX gene promoters. Additionally, BrBBX expression profiles in different tissues and in response to various abiotic stresses (heat, cold, salt, and drought) or hormones (abscisic acid, methyl jasmonate, and gibberellic acid) were analyzed by qRT-PCR. The data indicated that many B-box genes (e.g., BrBBX13, BrBBX15, and BrBBX17) may contribute to plant development and growth as well as abiotic stress tolerance. Overall, the identified BBX genes may be useful as functional genetic markers for multiple stress responses and plant developmental processes.

Overexpression of Ginkgo BBX25 enhances salt tolerance in Transgenic Populus

B-box (BBX) genes play important roles in plant growth, light morphogenesis, and environmental stress responses. Ginkgo (Ginkgo biloba L.) is known as a living fossil species that has a strong ability to adapt to environmental changes and tolerate harsh conditions. In this study, we chose this species to investigate the function of the GbBBX25 gene. We isolated the BBX gene from ginkgo and named it GbBBX25; this gene consists of an 819 bp open reading frame (ORF) that encodes 273 amino acids with two B-box domains but no CCT domain. GbBBX25 was localized in only the nucleus. The expression of GbBBX25 transcripts was observed in the leaves and was significantly enhanced under salt stress conditions. To further verify its function, we overexpressed the GbBBX25 gene in Populus davidiana × Populus bolleana and found that the transgenic Populus had greater soluble sugar levels and higher peroxidase (POD) activity in response to salt stress than nontransgenic (NT) Populus. Five genes related to salt stress were induced in transgenic plants with significantly higher expression levels than those in NT plants. This finding suggests that GbBBX25 improves the salt adaptation abilities of transgenic Populus and provides a scientific basis for related research.