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The calmodulin-binding transcription activator (CAMTA) family contributes to stress responses in many plant species. The Oryza sativa ssp. japonica genome harbors seven CAMTA genes; however, intraspecific variation and functional roles of this gene family have not been determined. Here, we comprehensively evaluated the structure and characteristics of the CAMTA genes in japonica rice using bioinformatics approaches and RT-qPCR. Within the CAMTA gene and promoter sequences, 527 single nucleotide polymorphisms were retrieved from 3,024 rice accessions. The CAMTA genes could be subdivided into 5–14 haplotypes. Association analyses between haplotypes and phenotypic traits, such as grain weight and salt stress parameters, identified phenotypic differences between rice subpopulations harboring different CAMTA haplotypes. Co-expression analyses and the identification of CAMTA-specific binding motifs revealed candidate genes regulated by CAMTA. A Gene Ontology functional enrichment analysis of 690 co-expressed genes revealed that CAMTA genes have key roles in defense responses. An interaction analysis identified 30 putative CAMTA interactors. Three genes were identified in co-expression and interaction network analyses, suggesting that they are potentially regulated by CAMTAs. Based on all information obtained together with the phenotypes of the CRISPR-Cas9 knockout mutant lines of three OskCAMTA genes generated, CAMTA1 likely plays important roles in the response to salt stress in rice. Overall, our findings suggest that the CAMTA gene family is involved in development and the salt stress response and reveal candidate target genes, providing a basis for further functional characterization. [ABSTRACT FROM AUTHOR]

The calmodulin-binding transcriptional activator (CAMTA) is a small, conserved gene family in plants that plays a crucial role in regulating growth, development, and responses to various abiotic stress. Given the significance of the CAMTA gene family, various studies have been dedicated to uncovering its functional characteristics. In this study, genome-wide identification and bioinformatics analysis were conducted to explore CAMTAs in Phoebe bournei. A total of 17 CAMTA genes, each containing at least one domain from CG-1, TIG, ANK, or IQ, were identified in the P. bournei genome. The diversity of PbCAMTAs could be varied depending on their subcellular localization. An analysis of protein motifs, domains, and gene structure revealed that members within the same subgroup exhibited similar organization, supporting the results of the phylogenetic analysis. Gene duplications occurred among members of the PbCAMTA gene family. According to the cis-regulatory element prediction and protein–protein interaction network analysis, eight genes were subjected to qRT-PCR under drought, heat, and light stresses. The expression profiles indicated that PbCAMTAs, particularly PbCAMTA2, PbCAMTA12, and PbCAMTA16, were induced by abiotic stress. This study provides profound insights into the functions of CAMTAs in P. bournei. [ABSTRACT FROM AUTHOR]

Abstract The calmodulin-binding transcription activator (CAMTA) family contributes to stress responses in many plant species. The Oryza sativa ssp. japonica genome harbors seven CAMTA genes; however, intraspecific variation and functional roles of this gene family have not been determined. Here, we comprehensively evaluated the structure and characteristics of the CAMTA genes in japonica rice using bioinformatics approaches and RT-qPCR. Within the CAMTA gene and promoter sequences, 527 single nucleotide polymorphisms were retrieved from 3,024 rice accessions. The CAMTA genes could be subdivided into 5–14 haplotypes. Association analyses between haplotypes and phenotypic traits, such as grain weight and salt stress parameters, identified phenotypic differences between rice subpopulations harboring different CAMTA haplotypes. Co-expression analyses and the identification of CAMTA-specific binding motifs revealed candidate genes regulated by CAMTA. A Gene Ontology functional enrichment analysis of 690 co-expressed genes revealed that CAMTA genes have key roles in defense responses. An interaction analysis identified 30 putative CAMTA interactors. Three genes were identified in co-expression and interaction network analyses, suggesting that they are potentially regulated by CAMTAs. Based on all information obtained together with the phenotypes of the CRISPR-Cas9 knockout mutant lines of three OskCAMTA genes generated, CAMTA1 likely plays important roles in the response to salt stress in rice. Overall, our findings suggest that the CAMTA gene family is involved in development and the salt stress response and reveal candidate target genes, providing a basis for further functional characterization.

Calmodulin-binding transcription activator (CAMTA) is an important calmodulin-binding protein with a conserved structure in eukaryotes which is widely involved in plant stress response, growth and development, hormone signal transduction, and other biological processes. Although CAMTA genes have been identified and characterized in many plant species, a systematic and comprehensive analysis of CAMTA genes in the Solanaceae genome is performed for the first time in this study. A total of 28 CAMTA genes were identified using bioinformatics tools, and the biochemical/physicochemical properties of these proteins were investigated. CAMTA genes were categorized into three major groups according to phylogenetic analysis. Tissue-expression profiles indicated divergent spatiotemporal expression patterns of SmCAMTAs. Furthermore, transcriptome analysis of SmCAMTA genes showed that exposure to cold induced differential expression of many eggplant CAMTA genes. Yeast two-hybrid and bimolecular fluorescent complementary assays suggested an interaction between SmCAMTA2 and SmERF1, promoting the transcription of the cold key factor SmCBF2, which may be an important mechanism for plant cold resistance. In summary, our results provide essential information for further functional research on Solanaceae family genes, and possibly other plant families, in the determination of the development of plants. [ABSTRACT FROM AUTHOR]

The calmodulin-binding transcriptional activator (CAMTA) is a small, conserved gene family in plants that plays a crucial role in regulating growth, development, and responses to various abiotic stress. Given the significance of the CAMTA gene family, various studies have been dedicated to uncovering its functional characteristics. In this study, genome-wide identification and bioinformatics analysis were conducted to explore CAMTAs in Phoebe bournei. A total of 17 CAMTA genes, each containing at least one domain from CG-1, TIG, ANK, or IQ, were identified in the P. bournei genome. The diversity of PbCAMTAs could be varied depending on their subcellular localization. An analysis of protein motifs, domains, and gene structure revealed that members within the same subgroup exhibited similar organization, supporting the results of the phylogenetic analysis. Gene duplications occurred among members of the PbCAMTA gene family. According to the cis-regulatory element prediction and protein–protein interaction network analysis, eight genes were subjected to qRT-PCR under drought, heat, and light stresses. The expression profiles indicated that PbCAMTAs, particularly PbCAMTA2, PbCAMTA12, and PbCAMTA16, were induced by abiotic stress. This study provides profound insights into the functions of CAMTAs in P. bournei.

Calmodulin-binding transcription activator (CAMTA) is an important calmodulin-binding protein with a conserved structure in eukaryotes which is widely involved in plant stress response, growth and development, hormone signal transduction, and other biological processes. Although CAMTA genes have been identified and characterized in many plant species, a systematic and comprehensive analysis of CAMTA genes in the Solanaceae genome is performed for the first time in this study. A total of 28 CAMTA genes were identified using bioinformatics tools, and the biochemical/physicochemical properties of these proteins were investigated. CAMTA genes were categorized into three major groups according to phylogenetic analysis. Tissue-expression profiles indicated divergent spatiotemporal expression patterns of SmCAMTAs. Furthermore, transcriptome analysis of SmCAMTA genes showed that exposure to cold induced differential expression of many eggplant CAMTA genes. Yeast two-hybrid and bimolecular fluorescent complementary assays suggested an interaction between SmCAMTA2 and SmERF1, promoting the transcription of the cold key factor SmCBF2, which may be an important mechanism for plant cold resistance. In summary, our results provide essential information for further functional research on Solanaceae family genes, and possibly other plant families, in the determination of the development of plants.

CAMTA are calcium-modulating binding transcription factors that contribute to plant development. We identified 46 CAMTA genes from eight Rosaceae species and divided them into five subgroups based on a phylogenetic tree. Our analysis indicated that CAMTA is a highly conserved family among Rosaceae species, with a conserved DNA-binding domain (CG-1) and a conserved transcription factor immunoglobulin domain (TIG). Following a recent whole-genome duplication event, the genomes of Chinese white pear, European pear, and apple experienced significant expansion, resulting in the number of CAMTA genes being twice that of the other species. Cis-element identification showed that the distribution of the zein metabolism regulation-responsive element was different in the promoters of Chinese white pear (55.56%) and European pear (11.11%) CAMTA gene families. The gene expression results showed that PbrCAMTA1, 2, 6, 7 was highly expressed in pear fruit. Among them, PbrCAMTA2 may have a key influence on fruit softening, as observed in transient transformation experiments. In conclusion, our results provide crucial insights into the evolution of the CAMTA gene family in pear and other Rosaceae species and identify a candidate PbrCAMTA gene, which is involved in the dynamic development of pear fruits. [ABSTRACT FROM AUTHOR]

This study investigated the potential regulatory mechanisms influencing chilling injury in peach fruit under various storage temperatures (0 ℃ and 5 ℃) and calcium treatments (calcium chloride (CaCl 2) and trifluoperazine (TFP)). The results showed that 0 ℃ storage and CaCl 2 treatment activated the expression of PpCAMTA5 , while repressed the expression of PpNAC25 , PpPAO , PpRBOHA , PpRBOHC , and PpRBOHD , and reduced hydrogen peroxide (H 2 O 2) content. This concerted regulation effectively suppressed chilling-induced browning in peach fruit during cold storage. However, the opposite effects were presented in TFP-treated fruit. Additionally, the interaction between PpCaM7 and PpCAMTA5 inhibited PpNAC25-mediated transcriptional activation of PpPAO , PpRBOHA , PpRBOHC , and PpRBOHD. Thus, these results suggested that the PpCaM7-PpCAMTA5 complex mitigates chilling injury in peach fruit via inhibiting reactive oxygen species (ROS) production. • 0℃ storage and CaCl 2 treatment mitigate peach browning during chilling injury. • 0℃ storage and CaCl 2 treatment inhibit the ROS metabolism in peach. • PpCAMTA5 and PpCaM7 bound to PpNAC25 promoters to suppress its transcription. • PpNAC25 negatively regulates ROS metabolism. [ABSTRACT FROM AUTHOR]

Calmodulin-binding transcription activator (CAMTA) is a transcription factor family containing calmodulin (CaM) binding sites and is involved in plant development. Although CAMTAs in Arabidopsis have been extensively investigated, the functions of CAMTAs remain largely unclear in peaches. In this study, we identified five peach CAMTAs which contained conserved CG-1 box, ANK repeats, CaM binding domain (CaMBD) and IQ motifs. Overexpression in tobacco showed that PpCAMTA1/2/3 were located in the nucleus, while PpCAMTA4 and PpCAMTA5 were located in the plasma membrane. Increased expression levels were observed for PpCAMTA1 and PpCAMTA3 during peach fruit ripening. Expression of PpCAMTA1 was induced by cold treatment and was inhibited by ultraviolet B irradiation (UV-B). Driven by AtCAMTA3 promoter, PpCAMTA1/2/3 were overexpressed in Arabidopsis mutant. Here, we characterized peach PpCAMTA1, representing an ortholog of AtCAMTA3. PpCAMTA1 expression in Arabidopsis complements the developmental deficiencies of the camta2,3 mutant, and restored the plant size to the wild type level. Moreover, overexpressing PpCAMTA1 in camta2,3 mutant inhibited salicylic acid (SA) biosynthesis and expression of SA-related genes, resulting in a susceptibility phenotype to Pst DC3000. Taken together, our results provide new insights for CAMTAs in peach fruit and indicate that PpCAMTA1 is associated with response to stresses during development. [ABSTRACT FROM AUTHOR]

Abstract Background Fruit ripening is an intricate developmental process driven by a highly coordinated action of complex hormonal networks. Ethylene is considered as the main phytohormone that regulates the ripening of climacteric fruits. Concomitantly, several ethylene-responsive transcription factors (TFs) are pivotal components of the regulatory network underlying fruit ripening. Calmodulin-binding transcription activator (CAMTA) is one such ethylene-induced TF implicated in various stress and plant developmental processes. Results Our comprehensive analysis of the CAMTA gene family in Durio zibethinus (durian, Dz) identified 10 CAMTAs with conserved domains. Phylogenetic analysis of DzCAMTAs, positioned DzCAMTA3 with its tomato ortholog that has already been validated for its role in the fruit ripening process through ethylene-mediated signaling. Furthermore, the transcriptome-wide analysis revealed DzCAMTA3 and DzCAMTA8 as the highest expressing durian CAMTA genes. These two DzCAMTAs possessed a distinct ripening-associated expression pattern during post-harvest ripening in Monthong, a durian cultivar native to Thailand. The expression profiling of DzCAMTA3 and DzCAMTA8 under natural ripening conditions and ethylene-induced/delayed ripening conditions substantiated their roles as ethylene-induced transcriptional activators of ripening. Similarly, auxin-suppressed expression of DzCAMTA3 and DzCAMTA8 confirmed their responsiveness to exogenous auxin treatment in a time-dependent manner. Accordingly, we propose that DzCAMTA3 and DzCAMTA8 synergistically crosstalk with ethylene during durian fruit ripening. In contrast, DzCAMTA3 and DzCAMTA8 antagonistically with auxin could affect the post-harvest ripening process in durian. Furthermore, DzCAMTA3 and DzCAMTA8 interacting genes contain significant CAMTA recognition motifs and regulated several pivotal fruit-ripening-associated pathways. Conclusion Taken together, the present study contributes to an in-depth understanding of the structure and probable function of CAMTA genes in the post-harvest ripening of durian.

Fungalysin metallopeptidase (M36), a hydrolase, catalyzes the hydrolysis of alanine, glycine, etc. Normally, it is considered to play an important role in the progress of fungal infection. However, the function of fungalysin metallopeptidase (M36) in Fusarium graminearum has not been reported. In this study, we explored the biological functions of FgFly1, a fungalysin metallopeptidase (M36) of F. graminearum. We found that ΔFgFly1 did not affect the ability to produce DON toxin, although it inhibited spore germination during asexual reproduction and reduction in pathogenicity compared with PH-1. Therefore, we speculated that FgFly1 affects the pathogenicity of F.graminearum by affecting pathways related to wheat disease resistance. Target protein TaCAMTA (calmodulin-binding transcription activator) was selected by a yeast two-hybrid (Y2H) system. Then, the interaction between FgFly1 and TaCAMTA was verified by bimolecular fluorescent complimentary (BiFC) and luciferase complementation assay (LCA). Furthermore, compared with wild-type Arabidopsis thaliana, the morbidity level of ΔAtCAMTA was increased after infection with F.graminearum, and the expression level of NPR1 was significantly reduced. Based on the above results, we concluded that FgFly1 regulated F. graminearum pathogenicity by interacting with host cell CAMTA protein. [ABSTRACT FROM AUTHOR]

Calmodulin-binding transcription activators (CAMTAs) are evolutionarily conserved transcription factors and have multi-functions in plant development and stress response. However, identification and functional analysis of tea plant (Camellia sinensis) CAMTA genes (CsCAMTAs) are still lacking. Here, five CsCAMTAs were identified from tea plant genomic database. Their gene structures were similar except CsCAMTA2, and protein domains were conserved. Phylogenetic relationship classified the CsCAMTAs into three groups, CsCAMTA2 was in group I, and CsCAMTA1, 3 and CsCAMTA4, 5 were, respectively, in groups II and III. Analysis showed that stress and phytohormone response-related cis-elements were distributed in the promoters of CsCAMTA genes. Expression analysis showed that CsCAMTAs were differentially expressed in different organs and under various stress treatments of tea plants. Three-hundred and four hundred-one positive co-expressed genes of CsCAMTAs were identified under cold and drought, respectively. CsCAMTAs and their co-expressed genes constituted five independent co-expression networks. KEGG enrichment analysis of CsCAMTAs and the co-expressed genes revealed that hormone regulation, transcriptional regulation, and protein processing-related pathways were enriched under cold treatment, while pathways like hormone metabolism, lipid metabolism, and carbon metabolism were enriched under drought treatment. Protein interaction network analysis suggested that CsCAMTAs could bind (G/A/C)CGCG(C/G/T) or (A/C)CGTGT cis element in the target gene promoters, and transcriptional regulation might be the main way of CsCAMTA-mediated functional regulation. The study establishes a foundation for further function studies of CsCAMTA genes in stress response. [ABSTRACT FROM AUTHOR]

Flesh softening is closely related to the quality of postharvest produces. Although the use of calcium chloride (CaCl 2) has been shown to inhibit fruit softening, the underlying molecular mechanisms have remained unclear. In our present investigation, CaCl 2 treatment resulted in an enhancement of cytosolic free Ca2+ and polysaccharide contents, firmness, and the integrity of the cell wall structure, particularly evident in the denser middle lamella of fresh-cut cantaloupe. CaCl 2 treatment also inhibited the cell wall degrading enzyme activities and gene expressions. Moreover, CmCAMTA2 could identify and bind to the CG-box structure of CmCellulase , Cmα-Gal3 , and Cmβ-Glu12 , thereby suppressing their transcription. In conclusion, current findings illustrated that CaCl 2 treatment triggered CmCAMTA2-mediated transcriptional suppression on cell wall degrading genes, inhibited the polysaccharide component degradation, and maintained better structure integrity of the cell wall, thereby delaying the flesh softening of fresh-cut cantaloupe. • CaCl 2 application delayed flesh softening of fresh-cut cantaloupe. • CaCl 2 maintained the structure integrity of cell wall in fresh-cut cantaloupe. • CaCl 2 lessened the polysaccharide component degradation of fresh-cut cantaloupe. • CaCl 2 treatment stimulated Ca2+ accumulation and the expression of CmCAMTA2. • Cell wall degradation was negatively modulated by Ca2+-CAMTA2 signal pathway. [ABSTRACT FROM AUTHOR]

CAMTA are calcium-modulating binding transcription factors that contribute to plant development. We identified 46 CAMTA genes from eight Rosaceae species and divided them into five subgroups based on a phylogenetic tree. Our analysis indicated that CAMTA is a highly conserved family among Rosaceae species, with a conserved DNA-binding domain (CG-1) and a conserved transcription factor immunoglobulin domain (TIG). Following a recent whole-genome duplication event, the genomes of Chinese white pear, European pear, and apple experienced significant expansion, resulting in the number of CAMTA genes being twice that of the other species. Cis-element identification showed that the distribution of the zein metabolism regulation-responsive element was different in the promoters of Chinese white pear (55.56%) and European pear (11.11%) CAMTA gene families. The gene expression results showed that PbrCAMTA1, 2, 6, 7 was highly expressed in pear fruit. Among them, PbrCAMTA2 may have a key influence on fruit softening, as observed in transient transformation experiments. In conclusion, our results provide crucial insights into the evolution of the CAMTA gene family in pear and other Rosaceae species and identify a candidate PbrCAMTA gene, which is involved in the dynamic development of pear fruits.

Exposure of plants to low temperatures adversely affects plant growth, development, and productivity. Plant response to cold stress is an intricate process that involves the orchestration of various physiological, signaling, biochemical, and molecular pathways. Calcium (Ca2+) signaling plays a crucial role in the acquisition of several stress responses, including cold. Upon perception of cold stress, Ca2+ channels and/or Ca2+ pumps are activated, which induces the Ca2+ signatures in plant cells. The Ca2+ signatures spatially and temporally act inside a plant cell and are eventually decoded by specific Ca2+ sensors. This series of events results in the molecular regulation of several transcription factors (TFs), leading to downstream gene expression and withdrawal of an appropriate response by the plant. In this context, calmodulin binding transcription activators (CAMTAs) constitute a group of TFs that regulate plant cold stress responses in a Ca2+ dependent manner. The present review provides a catalog of the recent progress made in comprehending the Ca2+ mediated cold acclimation in plants. [ABSTRACT FROM AUTHOR]

Various abiotic stresses like drought, salinity, high temperature, and chilling adversely affect plant growth and productivity. Terminal drought stress is one of the major concerns which limits the growth and yield of chickpeas. Calmodulin binding transcription activator (CAMTA) plays a vital role in stress tolerance in plants. In this study, the role of the CAMTA gene was assessed by over-expression in chickpea (Cicer arietinum L.) in response to drought and salinity stress. The over-expressing lines of the CAMTA gene have shown enhanced activities of various antioxidant enzymes (ascorbate peroxidase (APX), catalase (CAT), glutathione S-transferase (GST), superoxide dismutase (SOD), monodehydroascorbate reductase (MDHAR)). The reduced stress markers TBARS and H2O2 enhanced the survival of plants against both stresses. The physiological parameters (net photosynthesis; PN, transpiration; E, stomatal conductance; gs, photochemical quenching; qP, non-photochemical quenching; qN, and electron transport rate; ETR) were improved in the transgenics under both the stresses that protected the plants from damage. This investigation verified that the CAMTA gene provides tolerance against drought and salinity by maintaining biochemical, physiological, and morphological performances and could be exploited for genetic engineering strategies to overcome the stresses in other economically important crops. Key message: CAMTA transcription factor modulates drought and salinity stress in chickpea (Cicerarietinum L.). [ABSTRACT FROM AUTHOR]

Exposure of plants to low temperatures adversely affects plant growth, development, and productivity. Plant response to cold stress is an intricate process that involves the orchestration of various physiological, signaling, biochemical, and molecular pathways. Calcium (Ca2+) signaling plays a crucial role in the acquisition of several stress responses, including cold. Upon perception of cold stress, Ca2+ channels and/or Ca2+ pumps are activated, which induces the Ca2+ signatures in plant cells. The Ca2+ signatures spatially and temporally act inside a plant cell and are eventually decoded by specific Ca2+ sensors. This series of events results in the molecular regulation of several transcription factors (TFs), leading to downstream gene expression and withdrawal of an appropriate response by the plant. In this context, calmodulin binding transcription activators (CAMTAs) constitute a group of TFs that regulate plant cold stress responses in a Ca2+ dependent manner. The present review provides a catalog of the recent progress made in comprehending the Ca2+ mediated cold acclimation in plants.

Abstract Background Plant calmodulin-binding transcription activator (CAMTA) proteins play important roles in hormone signal transduction, developmental regulation, and environmental stress tolerance. However, in wheat, the CAMTA gene family has not been systematically characterized. Results In this work, 15 wheat CAMTA genes were identified using a genome-wide search method. Their chromosome location, physicochemical properties, subcellular localization, gene structure, protein domain, and promoter cis-elements were systematically analyzed. Phylogenetic analysis classified the TaCAMTA genes into three groups (groups A, B, and C), numbered 7, 6, and 2, respectively. The results showed that most TaCAMTA genes contained stress-related cis-elements. Finally, to obtain tissue-specific and stress-responsive candidates, the expression profiles of the TaCAMTAs in various tissues and under biotic and abiotic stresses were investigated. Tissue-specific expression analysis showed that all of the 15 TaCAMTA genes were expressed in multiple tissues with different expression levels, as well as under abiotic stress, the expressions of each TaCAMTA gene could respond to at least one abiotic stress. It also found that 584 genes in wheat genome were predicted to be potential target genes by CAMTA, demonstrating that CAMTA can be widely involved in plant development and growth, as well as coping with stresses. Conclusions This work systematically identified the CAMTA gene family in wheat at the whole-genome-wide level, providing important candidates for further functional analysis in developmental regulation and the stress response in wheat.

Background: Fruit ripening is an intricate developmental process driven by a highly coordinated action of complex hormonal networks. Ethylene is considered as the main phytohormone that regulates the ripening of climacteric fruits. Concomitantly, several ethylene-responsive transcription factors (TFs) are pivotal components of the regulatory network underlying fruit ripening. Calmodulin-binding transcription activator (CAMTA) is one such ethylene-induced TF implicated in various stress and plant developmental processes. Results: Our comprehensive analysis of the CAMTA gene family in Durio zibethinus (durian, Dz) identified 10 CAMTAs with conserved domains. Phylogenetic analysis of DzCAMTAs, positioned DzCAMTA3 with its tomato ortholog that has already been validated for its role in the fruit ripening process through ethylene-mediated signaling. Furthermore, the transcriptome-wide analysis revealed DzCAMTA3 and DzCAMTA8 as the highest expressing durian CAMTA genes. These two DzCAMTAs possessed a distinct ripening-associated expression pattern during post-harvest ripening in Monthong, a durian cultivar native to Thailand. The expression profiling of DzCAMTA3 and DzCAMTA8 under natural ripening conditions and ethylene-induced/delayed ripening conditions substantiated their roles as ethylene-induced transcriptional activators of ripening. Similarly, auxin-suppressed expression of DzCAMTA3 and DzCAMTA8 confirmed their responsiveness to exogenous auxin treatment in a time-dependent manner. Accordingly, we propose that DzCAMTA3 and DzCAMTA8 synergistically crosstalk with ethylene during durian fruit ripening. In contrast, DzCAMTA3 and DzCAMTA8 antagonistically with auxin could affect the post-harvest ripening process in durian. Furthermore, DzCAMTA3 and DzCAMTA8 interacting genes contain significant CAMTA recognition motifs and regulated several pivotal fruit-ripening-associated pathways. Conclusion: Taken together, the present study contributes to an in-depth understanding of the structure and probable function of CAMTA genes in the post-harvest ripening of durian. [ABSTRACT FROM AUTHOR]

Calmodulin-binding transcription activator (CAMTA) is a transcription factor family containing calmodulin (CaM) binding sites and is involved in plant development. Although CAMTAs in Arabidopsis have been extensively investigated, the functions of CAMTAs remain largely unclear in peaches. In this study, we identified five peach CAMTAs which contained conserved CG-1 box, ANK repeats, CaM binding domain (CaMBD) and IQ motifs. Overexpression in tobacco showed that PpCAMTA1/2/3 were located in the nucleus, while PpCAMTA4 and PpCAMTA5 were located in the plasma membrane. Increased expression levels were observed for PpCAMTA1 and PpCAMTA3 during peach fruit ripening. Expression of PpCAMTA1 was induced by cold treatment and was inhibited by ultraviolet B irradiation (UV-B). Driven by AtCAMTA3 promoter, PpCAMTA1/2/3 were overexpressed in Arabidopsis mutant. Here, we characterized peach PpCAMTA1, representing an ortholog of AtCAMTA3. PpCAMTA1 expression in Arabidopsis complements the developmental deficiencies of the camta2,3 mutant, and restored the plant size to the wild type level. Moreover, overexpressing PpCAMTA1 in camta2,3 mutant inhibited salicylic acid (SA) biosynthesis and expression of SA-related genes, resulting in a susceptibility phenotype to Pst DC3000. Taken together, our results provide new insights for CAMTAs in peach fruit and indicate that PpCAMTA1 is associated with response to stresses during development.

Cucurbita Linn. vegetables have a long history of cultivation and have been cultivated all over the world. With the increasing area of saline–alkali soil, Cucurbita Linn. is affected by salt stress, and calmodulin-binding transcription activator (CAMTA) is known for its important biological functions. Although the CAMTA gene family has been identified in several species, there is no comprehensive analysis on Cucurbita species. In this study, we analyzed the genome of Cucurbita maxima and Cucurbita moschata. Five C. moschata calmodulin-binding transcription activators (CmoCAMTAs) and six C. maxima calmodulin-binding transcription activators (CmaCAMTAs) were identified, and they were divided into three subfamilies (Subfamilies I, II, and III) based on the sequence identity of amino acids. CAMTAs from the same subfamily usually have similar exon–intron distribution and conserved domains (CG-1, TIG, IQ, and Ank_2). Chromosome localization analysis showed that CmoCAMTAs and CmaCAMTAs were unevenly distributed across four and five out of 21 chromosomes, respectively. There were a total of three duplicate gene pairs, and all of which had experienced segmental duplication events. The transcriptional profiles of CmoCAMTAs and CmaCAMTAs in roots, stems, leaves, and fruits showed that these CAMTAs have tissue specificity. Cis-acting elements analysis showed that most of CmoCAMTAs and CmaCAMTAs responded to salt stress. By analyzing the transcriptional profiles of CmoCAMTAs and CmaCAMTAs under salt stress, it was shown that both C. moschata and C. maxima shared similarities against salt tolerance and that it is likely to contribute to the development of these species. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) further demonstrated the key role of CmoCAMTAs and CmaCAMTAs under salt stress. This study provided a theoretical basis for studying the function and mechanism of CAMTAs in Cucurbita Linn.

Cucurbita Linn. vegetables have a long history of cultivation and have been cultivated all over the world. With the increasing area of saline–alkali soil, Cucurbita Linn. is affected by salt stress, and calmodulin-binding transcription activator (CAMTA) is known for its important biological functions. Although the CAMTA gene family has been identified in several species, there is no comprehensive analysis on Cucurbita species. In this study, we analyzed the genome of Cucurbita maxima and Cucurbita moschata. Five C. moschata calmodulin-binding transcription activators (CmoCAMTAs) and six C. maxima calmodulin-binding transcription activators (CmaCAMTAs) were identified, and they were divided into three subfamilies (Subfamilies I, II, and III) based on the sequence identity of amino acids. CAMTAs from the same subfamily usually have similar exon–intron distribution and conserved domains (CG-1, TIG, IQ, and Ank_2). Chromosome localization analysis showed that CmoCAMTAs and CmaCAMTAs were unevenly distributed across four and five out of 21 chromosomes, respectively. There were a total of three duplicate gene pairs, and all of which had experienced segmental duplication events. The transcriptional profiles of CmoCAMTAs and CmaCAMTAs in roots, stems, leaves, and fruits showed that these CAMTAs have tissue specificity. Cis -acting elements analysis showed that most of CmoCAMTAs and CmaCAMTAs responded to salt stress. By analyzing the transcriptional profiles of CmoCAMTAs and CmaCAMTAs under salt stress, it was shown that both C. moschata and C. maxima shared similarities against salt tolerance and that it is likely to contribute to the development of these species. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) further demonstrated the key role of CmoCAMTAs and CmaCAMTAs under salt stress. This study provided a theoretical basis for studying the function and mechanism of CAMTAs in Cucurbita Linn. [ABSTRACT FROM AUTHOR]

Fungalysin metallopeptidase (M36), a hydrolase, catalyzes the hydrolysis of alanine, glycine, etc. Normally, it is considered to play an important role in the progress of fungal infection. However, the function of fungalysin metallopeptidase (M36) in Fusarium graminearum has not been reported. In this study, we explored the biological functions of FgFly1, a fungalysin metallopeptidase (M36) of F. graminearum. We found that ΔFgFly1 did not affect the ability to produce DON toxin, although it inhibited spore germination during asexual reproduction and reduction in pathogenicity compared with PH-1. Therefore, we speculated that FgFly1 affects the pathogenicity of F.graminearum by affecting pathways related to wheat disease resistance. Target protein TaCAMTA (calmodulin-binding transcription activator) was selected by a yeast two-hybrid (Y2H) system. Then, the interaction between FgFly1 and TaCAMTA was verified by bimolecular fluorescent complimentary (BiFC) and luciferase complementation assay (LCA). Furthermore, compared with wild-type Arabidopsis thaliana, the morbidity level of ΔAtCAMTA was increased after infection with F.graminearum, and the expression level of NPR1 was significantly reduced. Based on the above results, we concluded that FgFly1 regulated F. graminearum pathogenicity by interacting with host cell CAMTA protein.

Calcium (Ca2+) ion is a critical ubiquitous intracellular second messenger, acting as a lead currency for several distinct signal transduction pathways. Transient perturbations in free cytosolic Ca2+ ([Ca2+]cyt) concentrations are indispensable for the translation of signals into adaptive biological responses. The transient increase in [Ca2+]cyt levels is sensed by an array of Ca2+ sensor relay proteins such as calmodulin (CaM), eventually leading to conformational changes and activation of CaM. CaM, in a Ca2+-dependent manner, regulates several transcription factors (TFs) that are implicated in various molecular, physiological, and biochemical functions in cells. CAMTA (calmodulin-binding transcription activator) is one such member of the Ca2+-loaded CaM-dependent family of TFs. The present review focuses on Ca2+ as a second messenger, its interaction with CaM, and Ca2+/CaM-mediated CAMTA transcriptional regulation in plants. The review recapitulates the molecular and physiological functions of CAMTA in model plants and various crops, confirming its probable involvement in stress signaling pathways and overall plant development. Studying Ca2+/CaM-mediated CAMTA TF will help in answering key questions concerning signaling cascades and molecular regulation under stress conditions and plant growth, thus improving our knowledge for crop improvement.

Calcium (Ca2+) ion is a critical ubiquitous intracellular second messenger, acting as a lead currency for several distinct signal transduction pathways. Transient perturbations in free cytosolic Ca2+ ([Ca2+]cyt) concentrations are indispensable for the translation of signals into adaptive biological responses. The transient increase in [Ca2+]cyt levels is sensed by an array of Ca2+ sensor relay proteins such as calmodulin (CaM), eventually leading to conformational changes and activation of CaM. CaM, in a Ca2+-dependent manner, regulates several transcription factors (TFs) that are implicated in various molecular, physiological, and biochemical functions in cells. CAMTA (calmodulin-binding transcription activator) is one such member of the Ca2+-loaded CaM-dependent family of TFs. The present review focuses on Ca2+ as a second messenger, its interaction with CaM, and Ca2+/CaM-mediated CAMTA transcriptional regulation in plants. The review recapitulates the molecular and physiological functions of CAMTA in model plants and various crops, confirming its probable involvement in stress signaling pathways and overall plant development. Studying Ca2+/CaM-mediated CAMTA TF will help in answering key questions concerning signaling cascades and molecular regulation under stress conditions and plant growth, thus improving our knowledge for crop improvement. [ABSTRACT FROM AUTHOR]

The calmodulin-binding transcription activator (CAMTA), as one of the most distinctive families of transcription factors, plays an important role in plant growth and development and in the stress response. However, it is currently unknown whether CAMTA exists in cucumbers and what its function is. In this study, we first identified four CAMTA genes in the cucumber genome using a genome-wide search method. Subsequently, we analyzed their physical and chemical properties, gene structure, protein domains, and phylogenetic relationships. The results show that the structure of CsCAMTAs is similar to that of other plants, and a phylogenetic analysis divides them into three groups. The analysis of cis-acting elements shows that most CsCAMTAs contain a variety of hormones and stress-related elements. The RT-PCR analysis shows that CsCAMTAs have different expression levels in different tissues and can be induced by IAA, ABA, MeJA, NaCl, and PEG. Finally, we analyzed the expression pattern of CsCAMTAs’ alternative spliceosomes under salt and drought stress. The results show that the expression levels of the different spliceosomes are affected by the type of stress and the duration of stress. These data indicate that CsCAMTAs participate in growth and development and in the stress response in cucumbers, a finding which lays the foundation for future CsCAMTAs’ functional research.

Human regulatory CD4+CD25+FOXP3+ T cells (Treg) play important roles in the maintenance of self-tolerance and immune homeostasis in various disease settings and are also involved in the suppression of effective immune responses. These cells are heterogeneous in phenotype and function, and the ability to reliably distinguish between various FOXP3-expressing subpopulations can affect the development of successful therapies. This study demonstrates that hypomethylated CpG sites, present in four regions of the FOXP3 locus, CAMTA1 and FUT7 gene regions, can be used to distinguish several subsets of Treg from conventional CD4+ T lymphocytes (Tcon) in donors of both genders. We describe a previously unreported strand-bias hemimethylation pattern in FOXP3 promoter and TSDR in donors of both genders, with the coding strand being demethylated within promoter and methylated within TSDR in all CD4+ lymphocyte subtypes, whereas the template strand follows the previously described pattern of methylation with both regions being more demethylated in Treg subtypes and mostly methylated in Tcon. This strand-specific approach within the TSDR may prove to be instrumental in correctly defining Treg subsets in health and in disease.

Summary: In plants, the calmodulin‐binding transcription activators (CAMTAs) are required for transcriptional regulation of abiotic and biotic stress responses. Among them, CAMTA3 in Arabidopsis has been intensively studied and shown to function redundantly with CAMTA1 and CAMTA2 to negatively regulate plant immunity. The camta1/2/3 triple mutant accordingly exhibits severe dwarfism due to autoimmunity. Here, through a suppressor screen using camta1/2/3 triple mutant, we found that a mutation in Cyclin‐Dependent Kinase 8 (CDK8) partially suppresses the dwarfism and constitutive resistance phenotypes of camta1/2/3. CDK8 positively regulates steady‐state salicylic acid (SA) levels and systemic required resistance (SAR). The expression of SA biosynthesis genes such as ICS1 and EDS5 is down‐regulated in cdk8 mutants under uninfected conditions, suggesting that CDK8 contributes to the transcriptional regulation of these SA pathway genes. Knocking out another Mediator kinase module member MED12 yielded similar defects including decreased steady‐state SA level and compromised SAR, suggesting that the whole Mediator kinase module contributes to the transcriptional regulation of SA levels and SAR. Significance Statement: Knockout analysis of cdk8 and med12 mutants revealed that both mutants accumulate less defense hormone salicylic acid (SA), revealing the positive contribution of the kinase module of Mediator to the transcriptional regulation of SA accumulation and systemic acquired resistance (SAR). Such mechanisms helps us to better understand the complex regulatory roles of Mediator in plant immunity. [ABSTRACT FROM AUTHOR]

The calmodulin-binding transcriptional activator (CAMTA) family was first observed in tobacco (NtER1) during a screening for the CaM-binding proteins, which are known to be one of the fast response stress proteins. Due to the increased importance of plant transcription factors in recent years; genome-wide identification of CAMTA genes has been performed in several plant species, except for Phaseolus vulgaris. Therefore, our aim was to identify and characterize CAMTA genes in P. vulgaris via in silico genome-wide analysis approach. Our results showed a total of eight CAMTA genes that were identified and observed on five out of 11 chromosomes of P. vulgaris. Four gene couples were found to be segmentally-duplicated and these segmental duplication events were shown to occur from 29.97 to 92.06 MYA. The phylogenetic tree of CAMTA homologs from P. vulgaris, A. thaliana, and G. max. revealed three groups based on their homology and the intron numbers of Pvul-CAMTA genes, ranged from 11 to 12. According to the syteny analysis; CAMTA genes of P. vulgaris and G. max revealed higher similarity, because they have highly similar genomes compared to A. thaliana. All Pvul-CAMTA genes were targeted by miRNAs, which play a role in response mechanism of salt stress. To detect expression levels in different plant tissues, mRNA analysis of Pvul-CAMTA genes were performed using publicly available expression data in Phytozome v12.1. In addition, responses of Pvul-CAMTA genes to salt stress, were also examined via both RNAseq and qRT-PCR analysis. To identify and to obtain insight into biological functions of CAMTA genes in the genome of P. vulgaris, several analyses were conducted using many online and offline bioinformatic tools, genome databases and qRT-PCR analyses. Due to this study being the first in the identification of CAMTA genes in P. vulgaris, this study could be considered as an useful source for future CAMTA genes studies in either P. vulgaris or comparative different plant species. [ABSTRACT FROM AUTHOR]

In plants, CAMTA (Calmodulin-binding transcription activator) proteins have been widely analysed, due to their vital roles in developmental regulation, environmental stress response, and hormone crosstalk. However, in citrus, this gene family, to date, has not been systematically characterised. In this study, 9 CitCAMTA genes have been identified from the citrus (Citrus sinensis and Citrus clementina) genomes. Their phylogenetic relationship, protein domain, exon-intron structure, and so forth were investigated in detail, revealing the divergence in their functions. Tissue-specific expression analysis showed that these CitCAMTA genes - with the exception of CitCAMTA4 - could be expressed in at least 1 tissue, indicating their roles in the development of root, stem, leaf, cotyledon, seed, and fruit peel. Under stress and hormone treatments, the expression patterns of each CitCAMTA remarkably varied, which showed a promising for improving citrus adaptation to stresses. Unexpectedly, the expression level of CitCAMTA4 was undetectable under all treatments. Taken together, our work lays a foundation for further analysis on citrus CAMTA genes, and provides a basic understanding of their roles in stress responses. [ABSTRACT FROM AUTHOR]

Human regulatory CD4+CD25+FOXP3+ T cells (Treg) play important roles in the maintenance of self-tolerance and immune homeostasis in various disease settings and are also involved in the suppression of effective immune responses. These cells are heterogeneous in phenotype and function, and the ability to reliably distinguish between various FOXP3-expressing subpopulations can affect the development of successful therapies. This study demonstrates that hypomethylated CpG sites, present in four regions of the FOXP3 locus, CAMTA1 and FUT7 gene regions, can be used to distinguish several subsets of Treg from conventional CD4+ T lymphocytes (Tcon) in donors of both genders. We describe a previously unreported strand-bias hemimethylation pattern in FOXP3 promoter and TSDR in donors of both genders, with the coding strand being demethylated within promoter and methylated within TSDR in all CD4+ lymphocyte subtypes, whereas the template strand follows the previously described pattern of methylation with both regions being more demethylated in Treg subtypes and mostly methylated in Tcon. This strand-specific approach within the TSDR may prove to be instrumental in correctly defining Treg subsets in health and in disease. [ABSTRACT FROM AUTHOR]

Calmodulin-binding transcription activators (CAMTAs) play important roles in various plant biological processes including disease resistance and abiotic stress tolerance. Oilseed rape (Brassica napus L.) is one of the most important oil-producing crops worldwide. To date, compositon of CAMTAs in genomes of Brassica species and role of CAMTAs in resistance to the devastating necrotrophic fungal pathogen Sclerotinia sclerotiorum are still unknown. In this study, 18 CAMTA genes were identified in oilseed rape genome through bioinformatics analyses, which were inherited from the nine copies each in its progenitors B. rapa and B. oleracea and represented the highest number of CAMTAs in a given plant species identified so far. Gene structure, protein domain organization and phylogentic analyses showed that the oilseed rape CAMTAs were structurally similar and clustered into three major groups as other plant CAMTAs, but had expanded subgroups CAMTA3 and CAMTA4 genes uniquely in rosids species occurring before formation of oilseed rape. A large number of stress response-related cis-elements existed in the 1.5 kb promoter regions of the BnCAMTA genes. BnCAMTA genes were expressed differentially in various organs and in response to treatments with plant hormones and the toxin oxalic acid (OA) secreted by S. sclerotiorum as well as the pathogen inoculation. Remarkably, the expression of BnCAMTA3A1 and BnCAMTA3C1 was drastically induced in early phase of S. sclerotiorum infection, indicating their potential role in the interactions between oilseed rape and S. sclerotiorum. Furthermore, inoculation analyses using Arabidopsis camta mutants demonstrated that Atcamta3 mutant plants exhibited significantly smaller disease lesions than wild-type and other Atcamta mutant plants. In addition, compared with wild-type plants, Atcamta3 plants accumulated obviously more hydrogen peroxide in response to the PAMP chitin and exhibited much higher expression of the CGCG-box-containing genes BAK1 and JIN1, which are essential to the PAMP triggered immunity (PTI) and/or plant resistance to pathogens including S. sclerotiorum. Our results revealed that CAMTA3 negatively regulated PTI probably by directly targeting BAK1 and it also negatively regulated plant defense through suppressing JA signaling pathway probably via directly targeting JIN1.

Calmodulin-binding transcription activator (CAMTA) constitutes one of the most important Ca2+/CaM-regulated transcription factor families in plants. Nevertheless, the phylogeny, protein interaction network and role in nonhost resistance of plant CAMTAs are not well understood. In this study, 200 CAMTA genes were identified from 35 species representing four major plant lineages. The CAMTA genes were conserved in multicellular land plants but absent in unicellular eukaryotes, and were likely to emerge from the fusion of two separate genes encoding a CAMTA-like protein and an IQ/CaM binding motif containing protein, respectively, in the embryophyta lineage ancestor. Approximately one fourth of plant CAMTAs did not contain a TIG domain. This non-TIG class of CAMTAs seems to have newly evolved through mutation of some key amino acids in the TIG domain of flowering land plants after divergence from the non-flowering plants. Phylogenetic analysis classified CAMTA proteins into three major groups and nine distinct subgroups, a result supported by protein domain and motif conservation analyses. Most (59.0% and 21.5%) of the identified CAMTA genes contained 12 or 11 introns, respectively. Gene duplication, intron invasion, enlargement and turnover, as well as exon rearrangements and skipping have apparently occurred during evolution of the CAMTA family. Moreover, 38 potential interactors of six Arabidopsis CAMTAs were predicted and 10 predicted target genes of AtCAMTA3 exhibited changes in expression between Atcamta3 mutants and wild-type plants. The majority of predicted interactors are transcription factors and/or Ca2+/CaM-regulated proteins, suggesting that transcriptional regulation of the target genes might be the dominant functional mechanism of AtCAMTAs, and AtCAMTAs might act together with other Ca2+ signaling components to regulate Ca2+-related biological processes. Furthermore, functional analyses employing Atcamta mutants revealed that AtCAMTA3 negatively regulated the immunity triggered by flg22 and nonhost resistance to Xanthomonas oryzae pv. oryzae via repressing accumulation of reactive oxygen species probably by targeting CBP60G, EDS1 and NDR1 and involving SA pathway.

Calmodulin-binding transcription activators (CAMTAs) play important roles in various plant biological processes including disease resistance and abiotic stress tolerance. Oilseed rape (Brassica napus L.) is one of the most important oil-producing crops worldwide. To date, compositon of CAMTAs in genomes of Brassica species and role of CAMTAs in resistance to the devastating necrotrophic fungal pathogen Sclerotinia sclerotiorum are still unknown. In this study, 18 CAMTA genes were identified in oilseed rape genome through bioinformatics analyses, which were inherited from the nine copies each in its progenitors Brassica rapa and Brassica oleracea and represented the highest number of CAMTAs in a given plant species identified so far. Gene structure, protein domain organization and phylogentic analyses showed that the oilseed rape CAMTAs were structurally similar and clustered into three major groups as other plant CAMTAs, but had expanded subgroups CAMTA3 and CAMTA4 genes uniquely in rosids species occurring before formation of oilseed rape. A large number of stress response-related cis-elements existed in the 1.5 kb promoter regions of the BnCAMTA genes. BnCAMTA genes were expressed differentially in various organs and in response to treatments with plant hormones and the toxin oxalic acid (OA) secreted by S. sclerotiorum as well as the pathogen inoculation. Remarkably, the expression of BnCAMTA3A1 and BnCAMTA3C1 was drastically induced in early phase of S. sclerotiorum infection, indicating their potential role in the interactions between oilseed rape and S. sclerotiorum. Furthermore, inoculation analyses using Arabidopsis camta mutants demonstrated that Atcamta3 mutant plants exhibited significantly smaller disease lesions than wild-type and other Atcamta mutant plants. In addition, compared with wild-type plants, Atcamta3 plants accumulated obviously more hydrogen peroxide in response to the PAMP chitin and exhibited much higher expression of the CGCG-box-containing genes BAK1 and JIN1, which are essential to the PAMP triggered immunity (PTI) and/or plant resistance to pathogens including S. sclerotiorum. Our results revealed that CAMTA3 negatively regulated PTI probably by directly targeting BAK1 and it also negatively regulated plant defense through suppressing JA signaling pathway probably via directly targeting JIN1. [ABSTRACT FROM AUTHOR]

Calmodulin-binding transcription activator (CAMTA) constitutes one of the most important Ca2+/CaM-regulated transcription factor families in plants. Nevertheless, the phylogeny, protein interaction network, and role in nonhost resistance of plant CAMTAs are not well understood. In this study, 200 CAMTA genes were identified from 35 species representing four major plant lineages. The CAMTA genes were conserved in multicellular land plants but absent in unicellular eukaryotes, and were likely to emerge from the fusion of two separate genes encoding a CAMTA-like protein and an IQ/CaM binding motif containing protein, respectively, in the embryophyta lineage ancestor. Approximately one fourth of plant CAMTAs did not contain a TIG domain. This non-TIG class of CAMTAs seems to have newly evolved through mutation of some key amino acids in the TIG domain of flowering land plants after divergence from the non-flowering plants. Phylogenetic analysis classified CAMTA proteins into three major groups and nine distinct subgroups, a result supported by protein domain and motif conservation analyses. Most (59.0 and 21.5%) of the identified CAMTA genes contained 12 or 11 introns, respectively. Gene duplication, intron invasion, enlargement and turnover, as well as exon rearrangements and skipping have apparently occurred during evolution of the CAMTA family. Moreover, 38 potential interactors of six Arabidopsis CAMTAs were predicted and 10 predicted target genes of AtCAMTA3 exhibited changes in expression between Atcamta3 mutants and wild-type plants. The majority of predicted interactors are transcription factors and/or Ca2+/CaM-regulated proteins, suggesting that transcriptional regulation of the target genes might be the dominant functional mechanism of AtCAMTAs, and AtCAMTAs might act together with other Ca2+ signaling components to regulate Ca2+-related biological processes. Furthermore, functional analyses employing Atcamta mutants revealed that AtCAMTA3 negatively regulated the immunity triggered by flg22 and nonhost resistance to Xanthomonas oryzae pv. oryzae via repressing accumulation of reactive oxygen species probably by targeting CBP60G, EDS1, and NDR1 and involving SA pathway. [ABSTRACT FROM AUTHOR]

In recent years, a novel family of calmodulin-binding transcription activators (CAMTAs) has been reported in various species. The CAMTAs share a conserved domain organization, with a CG-1 DNA-binding domain, a transcription factor immunoglobulin domain, several ankyrin repeats, a calmodulin-binding domain, and a varying number of IQ motifs. CAMTAs participate in transcriptional regulation by recognizing and binding to a specific cis-element: (G/A/C) CGCG(C/G/T). Plants suffer from the environmental challenges, including abiotic and biotic stresses. Investigations in various plant species indicate a broad range of CAMTA functions involved in developmental regulation, environmental stress response, and hormone cross talk. In this review, we focus on the expression patterns and biological functions of CAMTAs to explore their probable applications in biotechnology. Furthermore, the identification and phylogenetic analysis of CAMTAs in crops could open new perspectives for enhancing stress tolerance, which could lead to improved crop production. [ABSTRACT FROM AUTHOR]

Flesh lignification is a typical chilling injury (CI) symptom of loquat fruit during cold storage. Calcium chloride (CaCl 2) could enhance chilling tolerance in loquat fruit, but the molecular mechanism is still not illuminated. In this study, CaCl 2 treatment could decrease the activities and genes expression of peroxidase (POD) laccase (LAC), and inhibit the increase in firmness and lignin accumulation, thereby alleviating chilling-induced lignification in loquat fruit. Additionally, CaCl 2 enhanced the calmodulin (CaM) content, free Ca2+ distribution, EjCaM7 , and CaM binding transcription activator 3 (EjCAMTA3) expression in loquat fruit during cold storage, indicating Ca2+/CaM-CAMTA might be played a key role in response to cold stress. Moreover, the EjCAMTA3 and EjCaM7 proteins were identified and characterized from loquat fruit. EjCAMTA3 bound to the CG-box in EjPOD64 and EjLAC12-like promoters to repress their transcription. Further analysis revealed that EjCaM7 interacted with EjCAMTA3 in a Ca2+-dependent manner, and this interaction enhanced the EjCAMTA3-mediated transcriptional repression of EjPOD64 and EjLAC12-like genes. Taken together, these findings suggested that CaCl 2 treatment alleviates chilling-induced lignification in loquat fruit, which probably via the synergistic role of EjCaM7 and EjCAMTA3 in the modulation of EjPOD64 and EjLAC12-like genes expression, leading to the repression of lignin polymerization. • CaCl 2 treatment could alleviate chilling-induced lignification in loquat fruit. • CaCl 2 treatment induced Ca2+ signaling in loquat fruit under cold stress. • EjCAMTA3 bound to EjPOD64 and EjLAC12-like promoters to repress their transcription. • EjCaM7 enhanced EjCAMTA3-mediated repression of lignin polymerization. [ABSTRACT FROM AUTHOR]

Calmodulin-binding transcription activators (CAMTAs) are evolutionarily conserved transcription factors and have multi-functions in plant development and stress response. However, identification and functional analysis of tea plant ( Camellia sinensis ) CAMTA genes ( CsCAMTAs ) are still lacking. Here, five CsCAMTAs were identified from tea plant genomic database. Their gene structures were similar except CsCAMTA2 , and protein domains were conserved. Phylogenetic relationship classified the CsCAMTAs into three groups, CsCAMTA2 was in group I, and CsCAMTA1, 3 and CsCAMTA4, 5 were, respectively, in groups II and III. Analysis showed that stress and phytohormone response-related cis -elements were distributed in the promoters of CsCAMTA genes. Expression analysis showed that CsCAMTAs were differentially expressed in different organs and under various stress treatments of tea plants. Three-hundred and four hundred-one positive co-expressed genes of CsCAMTAs were identified under cold and drought, respectively. CsCAMTAs and their co-expressed genes constituted five independent co-expression networks. KEGG enrichment analysis of CsCAMTAs and the co-expressed genes revealed that hormone regulation, transcriptional regulation, and protein processing-related pathways were enriched under cold treatment, while pathways like hormone metabolism, lipid metabolism, and carbon metabolism were enriched under drought treatment. Protein interaction network analysis suggested that CsCAMTAs could bind (G/A/C)CGCG(C/G/T) or (A/C)CGTGT cis element in the target gene promoters, and transcriptional regulation might be the main way of CsCAMTA -mediated functional regulation. The study establishes a foundation for further function studies of CsCAMTA genes in stress response., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Zhou, Zhao, Xing, Mao, Wang, Dai, Niu and Yuan.)

Auxin is a key plant hormone that regulates various aspects of plant development. However, the mechanisms integrating auxin growth effects with stress responses are not fully understood. In this study, we investigated the possible role of calmodulin-binding transcription activator 1 ( CAMTA1), an Arabidopsis thaliana calcium/calmodulin-binding transcription activator, in auxin signaling and its responses to different stresses. Plants harboring the AtCAMTA1 promoter fused to the GUS reporter gene revealed cell-specific expression patterns reminiscent of auxin responses. The responsiveness of CAMTA1 to auxin was further assessed by chemical disturbances in polar auxin transport, and by RT-PCR analysis of gene expression of dissected leaf sections from plants exposed to the auxin transport inhibitor NPA. Furthermore, the intensity and cell-specific expression patterns of CAMTA1 changed significantly and differentially on exposure to increasing salt concentrations and heat. Transcriptome analysis of a camta1 T-DNA insertion mutant revealed 63 up-regulated genes, of which 17 are associated with auxin signaling. Finally, analysis of hypocotyl elongation in the presence and absence of auxin revealed that camta1 T-DNA insertion mutants and CAMTA1-repressor lines are hyper-responsive to auxin compared to wild-type seedlings. Thus, CAMTA1 participates in auxin signaling and responds to abiotic stresses. [ABSTRACT FROM AUTHOR]

Rapid deactivation of the Drosophila light receptor rhodopsin, through a visual arrestin Arr2 and a pathway that involves a transcription factor dCAMTA, is required for timely termination of light responses in the photoreceptor neuron. Here we report that this process is also critical for maintenance of the photoreceptor sensitivity. In both dCAMTA- and arr2-mutant flies, the endocytosis of the major rhodopsin Rh1 was dramatically increased, which was mediated by a Gq protein that signals downstream of rhodopsin in the visual transduction pathway. Consequently, the Rh1 level was downregulated and the photoreceptor became less sensitive to light. Remarkably, the Gq-stimulated Rh1 endocytosis does not require phospholipase C, a known effector of Gq, but depends on a tetraspanin protein. Our work has identified an arrestin-independent endocytic pathway of G protein-coupled receptor in the fly. This pathway may also function in mammals and mediate an early feedback regulation of receptor signaling. [ABSTRACT FROM AUTHOR]

The calmodulin-binding transcription activator (CAMTA), as one of the most distinctive families of transcription factors, plays an important role in plant growth and development and in the stress response. However, it is currently unknown whether CAMTA exists in cucumbers and what its function is. In this study, we first identified four CAMTA genes in the cucumber genome using a genome-wide search method. Subsequently, we analyzed their physical and chemical properties, gene structure, protein domains, and phylogenetic relationships. The results show that the structure of CsCAMTAs is similar to that of other plants, and a phylogenetic analysis divides them into three groups. The analysis of cis-acting elements shows that most CsCAMTAs contain a variety of hormones and stress-related elements. The RT-PCR analysis shows that CsCAMTAs have different expression levels in different tissues and can be induced by IAA, ABA, MeJA, NaCl, and PEG. Finally, we analyzed the expression pattern of CsCAMTAs' alternative spliceosomes under salt and drought stress. The results show that the expression levels of the different spliceosomes are affected by the type of stress and the duration of stress. These data indicate that CsCAMTAs participate in growth and development and in the stress response in cucumbers, a finding which lays the foundation for future CsCAMTAs' functional research. [ABSTRACT FROM AUTHOR]

Calcium (Ca 2+ ) ion is a critical ubiquitous intracellular second messenger, acting as a lead currency for several distinct signal transduction pathways. Transient perturbations in free cytosolic Ca 2+ ([Ca 2+ ] cyt ) concentrations are indispensable for the translation of signals into adaptive biological responses. The transient increase in [Ca 2+ ] cyt levels is sensed by an array of Ca 2+ sensor relay proteins such as calmodulin (CaM), eventually leading to conformational changes and activation of CaM. CaM, in a Ca 2+ -dependent manner, regulates several transcription factors (TFs) that are implicated in various molecular, physiological, and biochemical functions in cells. CAMTA (calmodulin-binding transcription activator) is one such member of the Ca 2+ -loaded CaM-dependent family of TFs. The present review focuses on Ca 2+ as a second messenger, its interaction with CaM, and Ca 2+ /CaM-mediated CAMTA transcriptional regulation in plants. The review recapitulates the molecular and physiological functions of CAMTA in model plants and various crops, confirming its probable involvement in stress signaling pathways and overall plant development. Studying Ca 2+ /CaM-mediated CAMTA TF will help in answering key questions concerning signaling cascades and molecular regulation under stress conditions and plant growth, thus improving our knowledge for crop improvement., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Iqbal, Shariq Iqbal, Singh and Buaboocha.)