Calcium-dependent Protein Kinases Gene Research Articles

Genome-wide survey and expression analysis of the calcium-dependent protein kinase gene family in cassava.

Calcium-dependent protein kinases (CPKs) play important roles in regulating plant tolerance to abiotic stress and signal transduction; however, no data are currently available regarding the CPK family in cassava. Herein, we identified 27 CPK genes from cassava based on our previous genome sequencing data. Phylogenetic analysis showed that cassava CPKs could be clustered into three groups, which was further supported by gene structure and conserved protein motif analyses. Global expression analysis suggested that MeCPK genes showed distinct expression patterns in different tissues between wild subspecies and cultivated varieties, indicating their involvement in the functional diversity of different varieties. Transcriptomics, interaction networks, and co-expression assays revealed a broad transcriptional response of cassava CPKs and CPK-mediated networks to drought stress and their differential expression profiles in different varieties, implying their contribution to drought stress tolerance in cassava. Expression analysis of eight MeCPK genes suggested a comprehensive response to osmotic stress, salt, cold, abscisic acid, and H2O2, which indicated that cassava CPKs might be convergence points for different signaling pathways. This study provides a basis for crop improvements and understanding of abiotic stress responses and signal transduction mediated by CPKs in cassava.

Uncovering the differential molecular basis of adaptive diversity in three Echinochloa leaf transcriptomes.

Echinochloa is a major weed that grows almost everywhere in farmed land. This high prevalence results from its high adaptability to various water conditions, including upland and paddy fields, and its ability to grow in a wide range of climates, ranging from tropical to temperate regions. Three Echinochloa crus-galli accessions (EC-SNU1, EC-SNU2, and EC-SNU3) collected in Korea have shown diversity in their responses to flooding, with EC-SNU1 exhibiting the greatest growth among three accessions. In the search for molecular components underlying adaptive diversity among the three Echinochloa crus-galli accessions, we performed de novo assembly of leaf transcriptomes and investigated the pattern of differentially expressed genes (DEGs). Although the overall composition of the three leaf transcriptomes was well-conserved, the gene expression patterns of particular gene ontology (GO) categories were notably different among the three accessions. Under non-submergence growing conditions, five protein categories (serine/threonine kinase, leucine-rich repeat kinase, signaling-related, glycoprotein, and glycosidase) were significantly (FDR, q < 0.05) enriched in up-regulated DEGs from EC-SNU1. These up-regulated DEGs include major components of signal transduction pathways, such as receptor-like kinase (RLK) and calcium-dependent protein kinase (CDPK) genes, as well as previously known abiotic stress-responsive genes. Our results therefore suggest that diversified gene expression regulation of upstream signaling components conferred the molecular basis of adaptive diversity in Echinochloa crus-galli.

Genome-wide analysis and expression of the calcium-dependent protein kinase gene family in cucumber.

Calcium-dependent protein kinases (CDPKs) are multi-functional proteins that combine calcium-binding and signaling capabilities within a single gene product. Current studies have shown that the CDPKs regulate numerous growth and developmental processes and biotic and abiotic stress responses. Nonetheless, knowledge concerning the specific expression patterns and evolutionary history of the CDPK family in cucumber (Cucumis sativus L.) remains very limited. We, therefore, investigated the phylogenetic relationships and expression profiles of the 19 CDPK genes identified in the cucumber genome sequence, resolving them into four subfamilies based on a phylogenetic tree and gene structures. Tissue-specific expression profiles suggest that cucumber CDPK genes are involved in cucumber tissue development. An expression analysis based on qRT-PCR indicated that cucumber CDPK genes are extensively involved in abscisic acid, salt, cold, drought, heat, and waterlogging responses, possibly by different mechanisms. The fates of two paralogs after divergence were also investigated, suggesting subfunctionalization and neofunctionalization during evolution. These observations lay an important foundation for functional and evolutionary analyses of the CDPK gene family in cucurbitaceae species.

Genome-wide analysis of the calcium-dependent protein kinase gene family in Gossypium raimondii

Plant calcium-dependent protein kinases (CDPKs) play important roles in diverse physiological processes by regulating the downstream components of calcium signaling. To date, only a few species of the plant CDPK gene family have been functionally identified. In addition, there has been no systematic analysis of the CDPK family in cotton. Here, 41 putative cotton CDPK (GrCDPK) genes were identified via bioinformatics analysis of the entire genome of Gossypium raimondii and were classified into four groups based on evolutionary relatedness. Gene structure analysis indicated that most of these GrCDPK genes share a similar intron-exon structure (7 or 8 exons), strongly supporting their close evolutionary relationships. Chromosomal distributions and phylogenetics analysis showed that 13 pairs of GrCDPK genes arose via segmental duplication events. Furthermore, using microarray data of upland cotton (G. hirsutum L.), comparative profiles analysis of these GhCDPKs indicated that some of the encoding genes might be involved in the responses to multiple abiotic stresses and play important regulatory roles during cotton fiber development. This study is the first genome-wide analysis of the CDPK family in cotton, and it will provide valuable information for the further functional characterization of cotton CDPK genes.

Isolation and functional characterisation of CDPKs gene from Arachis hypogaea under salt stress.

One of salt-induced calcium-dependent protein kinases (CDPKs) gene was isolated from Arachis hypogeae L. by RACE method. The cDNA full length was 2241bp deposited in GenBank (number KF437909), designated as AhCDPK. The coding region sequence of AhCDPK was 1629bp and encoded a protein of 542 amino acids. The molecular weight and the theoretical isoelectric point of AhCDPK was 60.96kDa and 5.61 respectively. Amino acid sequence analysis indicated that AhCDPK has highest similarity and homology with Glycine max L. In addition, the AhCDPK amino acids were predicted to encode a hydrophilic protein which localised in the endoplasmic reticulum. AhCDPK seemed to transcript in all peanut organs, and had the highest expression in seeds. The expression of AhCDPK could be strongly induced by both Ca2+ and NaCl. When exposed to salt stress, overexpressing AhCDPK in tobacco could alleviate PSII photoinhibition by improving physiological states, such as reducing the accumulation of reactive oxygen species (ROS), improving the activity of antioxidant defence system enzymes and improving the accumulation of osmotic regulation substance. These results showed that AhCDPK has the same functions as that of G. max, and it could play an important role for peanut to resist salt stress.

Constitutive expression and silencing of a novel seed specific calcium dependent protein kinase gene in rice reveals its role in grain filling

Ca2+ sensor protein kinases are prevalent in most plant species including rice. They play diverse roles in plant signaling mechanism. Thirty one CDPK genes have been identified in rice and some are functionally characterized. In the present study, the newly identified rice CDPK gene OsCPK31 was functionally validated by overexpression and silencing in Taipei 309 rice cultivar. Spikelets of overexpressing plants showed hard dough stage within 15d after pollination (DAP) with rapid grain filling and early maturation. Scanning electron microscopy of endosperm during starch granule formation confirmed early grain filling. Further, seeds of overexpressing transgenic lines matured early (20–22 DAP) and the average number of maturity days reduced significantly. On the other hand, silencing lines showed more number of unfilled spikelet without any difference in maturity duration. It will be interesting to further decipher the role of OsCPK31 in biological pathways associated with distribution of photosynthetic assimilates during grain filling stage.

ZmCPK1, a calcium-independent kinase member of the Zea mays CDPK gene family, functions as a negative regulator in cold stress signalling.

Calcium-dependent protein kinases (CDPKs) have been shown to play important roles in plant environmental stress signal transduction. We report on the identification of ZmCPK1 as a member of the maize (Zea mays) CDPK gene family involved in the regulation of the maize cold stress response. Based upon in silico analysis of the Z. mays cv. B73 genome, we identified that the maize CDPK gene family consists of 39 members. Two CDPK members were selected whose gene expression was either increased (Zmcpk1) or decreased (Zmcpk25) in response to cold exposure. Biochemical analysis demonstrated that ZmCPK1 displays calcium-independent protein kinase activity. The C-terminal calcium-binding domain of ZmCPK1 was sufficient to mediate calcium independency of a previously calcium-dependent enzyme in chimeric ZmCPK25-CPK1 proteins. Furthermore, co-transfection of maize mesophyll protoplasts with active full-length ZmCPK1 suppressed the expression of a cold-induced marker gene, Zmerf3 (ZmCOI6.21). In accordance, heterologous overexpression of ZmCPK1 in Arabidopsis thaliana yielded plants with altered acclimation-induced frost tolerance. Our results identify ZmCPK1 as a negative regulator of cold stress signalling in maize.

Genome-wide survey and expression analysis of calcium-dependent protein kinase in Gossypium raimondii.

Calcium-dependent protein kinases (CDPKs) are one of the largest protein kinases in plants and participate in different physiological processes through regulating downstream components of calcium signaling pathways. In this study, 41 CDPK genes, from GrCPK1 to GrCPK41, were identified in the genome of the diploid cotton, Gossypium raimondii. The phylogenetic analysis indicated that all these genes were divided into four subgroups and members within the same subgroup shared conserved exon-intron structures. The expansion of GrCPKs family in G. raimondii was due to the segmental duplication events, and the analysis of Ka/Ks ratios implied that the duplicated GrCPKs had mainly undergone strong purifying selection pressure with limited functional divergence. The cold-responsive elements in promoter regions were detected in the majority of GrCPKs. The expression analysis of 11 selected genes showed that GrCPKs exhibited tissue-specific expression patterns and the expression of GrCPKs were induced or repressed by cold treatment. These observations would lay an important foundation for functional and evolutionary analysis of CDPK gene family in Gossypium species.

A rice calcium-dependent protein kinase OsCPK9 positively regulates drought stress tolerance and spikelet fertility.

BackgroundIn plants, calcium-dependent protein kinases (CDPKs) are involved in tolerance to abiotic stresses and in plant seed development. However, the functions of only a few rice CDPKs have been clarified. At present, it is unclear whether CDPKs also play a role in regulating spikelet fertility.ResultsWe cloned and characterized the rice CDPK gene, OsCPK9. OsCPK9 transcription was induced by abscisic acid (ABA), PEG6000, and NaCl treatments. The results of OsCPK9 overexpression (OsCPK9-OX) and OsCPK9 RNA interference (OsCPK9-RNAi) analyses revealed that OsCPK9 plays a positive role in drought stress tolerance and spikelet fertility. Physiological analyses revealed that OsCPK9 improves drought stress tolerance by enhancing stomatal closure and by improving the osmotic adjustment ability of the plant. It also improves pollen viability, thereby increasing spikelet fertility. In OsCPK9-OX plants, shoot and root elongation showed enhanced sensitivity to ABA, compared with that of wild-type. Overexpression and RNA interference of OsCPK9 affected the transcript levels of ABA- and stress-responsive genes.ConclusionsOur results demonstrated that OsCPK9 is a positive regulator of abiotic stress tolerance, spikelet fertility, and ABA sensitivity.

Evaluation of immune responses in mice after DNA immunization with putative Toxoplasma gondii calcium-dependent protein kinase 5.

Toxoplasma gondii can cause serious public health problems and economic losses worldwide. Calcium-dependent protein kinases (CDPKs) are key mediators of T. gondii signaling pathways and are implicated as important virulence factors. In the present study, we cloned a novel T. gondii CDPK gene, named TgCDPK5, and constructed the eukaryotic expression vector pVAX-CDPK5. Then, we evaluated the immune protection induced by pVAX-CDPK5 in Kunming mice. After injection of pVAX-CDPK5 intramuscularly, immune responses, determined with lymphoproliferative assays and cytokine and antibody measurements, were monitored, and mouse survival times and brain cyst formation were evaluated following challenges with the T. gondii RH strain (genotype I) and the PRU strain (genotype II). pVAX-CDPK5 effectively induced immune responses with increased specific antibodies, a predominance of IgG2a production, and a strong lymphocyte proliferative response. The levels of gamma interferon (IFN-γ), interleukin 2 (IL-2), and IL-12(p70) and the percentages of CD3(+) CD4(+) and CD3(+) CD8(+) cells in mice vaccinated with pVAX-CDPK5 were significantly increased. However, IL-4 and IL-10 were not produced in the vaccinated mice. These results demonstrate that pVAX-CDPK5 can elicit strong humoral and cellular Th1 immune responses. The survival time of immunized mice challenged with the T. gondii RH strain (8.67 ± 4.34 days) was slightly, but not significantly, longer than that in the control groups within 7 days (P > 0.05). The numbers of brain cysts in the mice in the pVAX-CDPK5 group were reduced by ∼40% compared with those in the control groups (P < 0.05), which provides a foundation for the further development of effective subunit vaccines against T. gondii.

QTLs for Seed Vigor-Related Traits Identified in Maize Seeds Germinated under Artificial Aging Conditions

High seed vigor is important for agricultural production due to the associated potential for increased growth and productivity. However, a better understanding of the underlying molecular mechanisms is required because the genetic basis for seed vigor remains unknown. We used single-nucleotide polymorphism (SNP) markers to map quantitative trait loci (QTLs) for four seed vigor traits in two connected recombinant inbred line (RIL) maize populations under four treatment conditions during seed germination. Sixty-five QTLs distributed between the two populations were identified and a meta-analysis was used to integrate genetic maps. Sixty-one initially identified QTLs were integrated into 18 meta-QTLs (mQTLs). Initial QTLs with contribution to phenotypic variation values of R2>10% were integrated into mQTLs. Twenty-three candidate genes for association with seed vigor traits coincided with 13 mQTLs. The candidate genes had functions in the glycolytic pathway and in protein metabolism. QTLs with major effects (R2>10%) were identified under at least one treatment condition for mQTL2, mQTL3-2, and mQTL3-4. Candidate genes included a calcium-dependent protein kinase gene (302810918) involved in signal transduction that mapped in the mQTL3-2 interval associated with germination energy (GE) and germination percentage (GP), and an hsp20/alpha crystallin family protein gene (At5g51440) that mapped in the mQTL3-4 interval associated with GE and GP. Two initial QTLs with a major effect under at least two treatment conditions were identified for mQTL5-2. A cucumisin-like Ser protease gene (At5g67360) mapped in the mQTL5-2 interval associated with GP. The chromosome regions for mQTL2, mQTL3-2, mQTL3-4, and mQTL5-2 may be hot spots for QTLs related to seed vigor traits. The mQTLs and candidate genes identified in this study provide valuable information for the identification of additional quantitative trait genes.

Identification, expression and interaction analyses of calcium-dependent protein kinase (CPK) genes in canola (Brassica napus L.).

BackgroundCanola (Brassica napus L.) is one of the most important oil-producing crops in China and worldwide. The yield and quality of canola is frequently threatened by environmental stresses including drought, cold and high salinity. Calcium is a well-known ubiquitous intracellular secondary messenger in plants. Calcium-dependent protein kinases (CPKs) are Ser/Thr protein kinases found only in plants and some protozoans. CPKs are Ca2+ sensors that have both Ca2+ sensing function and kinase activity within a single protein and play crucial roles in plant development and responses to various environmental stresses.ResultsIn this study, we mined the available expressed sequence tags (ESTs) of B. napus and identified a total of 25 CPK genes, among which cDNA sequences of 23 genes were successfully cloned from a double haploid cultivar of canola. Phylogenetic analysis demonstrated that they could be clustered into four subgroups. The subcellular localization of five selected BnaCPKs was determined using green fluorescence protein (GFP) as the reporter. Furthermore, the expression levels of 21 BnaCPK genes in response to salt, drought, cold, heat, abscisic acid (ABA), low potassium (LK) and oxidative stress were studied by quantitative RT-PCR and were found to respond to multiple stimuli, suggesting that canola CPKs may be convergence points of different signaling pathways. We also identified and cloned five and eight Clade A basic leucine zipper (bZIP) and protein phosphatase type 2C (PP2C) genes from canola and, using yeast two-hybrid and bimolecular fluorescence complementation (BiFC), determined the interaction between individual BnaCPKs and BnabZIPs or BnaPP2Cs (Clade A). We identified novel, interesting interaction partners for some of the BnaCPK proteins.ConclusionWe present the sequences and characterization of CPK gene family members in canola for the first time. This work provides a foundation for further crop improvement and improved understanding of signal transduction in plants.

Expression profiles of calcium-dependent protein kinase genes (CDPK1–14) in Agrobacterium rhizogenes pRiA4-transformed calli of Rubia cordifolia under temperature- and salt-induced stresses

Agrobacterium rhizogenes genetically transform plant cells naturally via horizontal gene transfer by the introduction of T-DNA from the Ri plasmid into genomic DNA to create favorable conditions for successful colonization. An intriguing feature of pRiA4-transformed cells is their recently discovered enhanced tolerance to abiotic stress stimuli and activation of antioxidant enzyme expression. The mechanism by which A. rhizogenes modulates the defense responses of transformed cells remains unclear. It has been established that calcium-dependent protein kinase (CDPK) genes mediate crosstalk of signaling pathways in plants, and these genes have been implicated in biotic and abiotic stress signaling. In this study, we identified fourteen CDPK genes from Rubia cordifolia and examined their expression in aerial plant organs as well as in non-transformed and A. rhizogenes A4-transformed calli. Expression of RcCDPK4, RcCDPK5, RcCDPK7, and RcCDPK10 was 1.2- to 3.9-fold higher in pRiA4-transformed cells than in non-transformed cells, whereas expression of RcCDPK1, RcCDPK9, RcCDPK11, and RcCDPK14 was 1.2- to 1.9-fold lower. Agrobacterium transformation substantially modified the transcriptional responses of specific RcCDPK isoforms in pRiA4-transformed cells under conditions of temperature- and salinity-induced stress. On the basis of the results, we suggest that A. rhizogenes T-DNA genes exert their diverse biological functions by altering the expression of various CDPK genes.

VaCPK20 gene overexpression significantly increased resveratrol content and expression of stilbene synthase genes in cell cultures of Vitis amurensis Rupr

Resveratrol, a naturally occurring plant phenol, has been reported to exhibit a wide range of valuable biological and pharmacological properties. In the present investigation, we show that transformation of a Vitis amurensis Rupr. cell suspension with the gene VaCPK20 for a calcium-dependent protein kinase (CDPK) under the control of double CaMV 35S promoter increased resveratrol production in five independently transformed cell lines in 9-68 times compared with control cells. The VaCPK20-transformed calli were capable of producing 0.04-0.42 % dry wt. of resveratrol, while the control calli produced up to 0.008 % dry wt. of resveratrol Also, we characterized expression of stilbene synthase (STS) genes in the five VaCPK20-transgenic cell lines of V. amurensis. In all VaCPK20-transgenic cell lines, expression of VaSTS7 increased; while expression of VaSTS1 decreased. We suggest that transformation of V. amurensis calli with the VaCPK20 gene induced resveratrol accumulation via enhancement of expression of the VaSTS7 gene involved in resveratrol biosynthesis. The obtained data first demonstrate that overexpression of a CDPK gene resulted in increased accumulation of a stilbenoid phytoalexine in transgenic plant cells. We propose that the VaCPK20 gene could play an important role in the regulation of resveratrol biosynthesis in grape cells.

Calcium-Dependent Protein Kinases in Plants: Evolution, Expression and Function

Calcium-dependent protein kinases (CPKs) are plant proteins that directly bind calcium ions before phosphorylating substrates involved in metabolism, osmosis, hormone response and stress signaling pathways. CPKs are a large multigene family of proteins that are present in all plants studied to date, as well as in protists, oomycetes and green algae, but are not found in animals and fungi. Despite the increasing evidence of the importance of CPKs in developmental and stress responses from various plants, a comprehensive genome-wide analysis of CPKs from algae to higher plants has not been undertaken. This paper describes the evolution of CPKs from green algae to plants using a broadly sampled phylogenetic analysis and demonstrates the functional diversification of CPKs based on expression and functional studies in different plant species. Our findings reveal that CPK sequence diversification into four major groups occurred in parallel with the terrestrial transition of plants. Despite significant expansion of the CPK gene family during evolution from green algae to higher plants, there is a high level of sequence conservation among CPKs in all plant species. This sequence conservation results in very little correlation between CPK evolutionary groupings and functional diversity, making the search for CPK functional orthologs a challenge.

Cloning and Expression Analysis of a Calcium-Dependent Protein Kinase Gene SiCDPK1 in Setaria italica

CDPK(calcium-dependent protein kinase) is a kind of essential calcium sensors and calcium responders, which plays important roles in response to various abiotic stresses in plants. In this research, we cloned the abiotic stress response related CDPK gene with RT-PCR in Setaria italica, designated as SiCDPK1(GenBank accession number KC249975.1). We predicted 28 CDPKs in the Setaria italica genome by using the known Arabidopsis CDPK sequences as query sequences. The phylogenetic analysis showed the SiCDPK gene family was divided into four subgroups, in which SiCDPK1 belongs to subgroup II. The ORF of SiCDPK1 contains 1596 bp, which encodes 531 amino acids. The predicted protein molecular weight is 59.5 kD and pI is 5.94. SiCDPK1 has conserved protein domains of CDPK. The regulatory element analysis of promoter in SiCDPK1 showed a lot of cis-acting elements associated with different abiotic stresses. The RT-PCR results showed that SiCDPK1 was induced by PEG, ABA, salinity and drought. The research on SiCDPK1 paves a way for unraveling the mechanism of abiotic stresses in plants.

The Evolutionary History and Diverse Physiological Roles of the Grapevine Calcium-Dependent Protein Kinase Gene Family

Calcium-dependent protein kinases (CDPKs) are molecular switches that bind Ca2+, ATP, and protein substrates, acting as sensor relays and responders that convert Ca2+ signals, created by developmental processes and environmental stresses, into phosphorylation events. The precise functions of the CDPKs in grapevine (Vitis vinifera) are largely unknown. We therefore investigated the phylogenetic relationships and expression profiles of the 17 CDPK genes identified in the 12x grapevine genome sequence, resolving them into four subfamilies based on phylogenetic tree topology and gene structures. The origins of the CDPKs during grapevine evolution were characterized, involving 13 expansion events. Transcriptomic analysis using 54 tissues and developmental stages revealed three types of CDPK gene expression profiles: constitutive (housekeeping CDPKs), partitioned functions, and prevalent in pollen/stamen. We identified two duplicated CDPK genes that had evolved from housekeeping to pollen-prevalent functions and whose origin correlated with that of seed plants, suggesting neofunctionalization with an important role in pollen development and also potential value in the breeding of seedless varieties. We also found that CDPKs were involved in three abiotic stress signaling pathways and could therefore be used to investigate the crosstalk between stress responses.

A novel calcium-dependent protein kinase gene from Populus euphratica, confers both drought and cold stress tolerance

Populus species are the most important timber trees over the Northern hemisphere. Most of them are cold- and drought-sensitive except the Populus euphratica Oliv. Here, a calcium-dependent protein kinase (CDPK) gene cloned from P. euphratica, designated as PeCPK10, was rapidly induced by salt, cold, and drought stresses. The protein encoded by PeCPK10 was localized within the nucleus and cytosol, which may be important for its specific regulation in cellular functions. To elucidate the physiological functions of PeCPK10, we generated transgenic Arabidopsis plants overexpressing PeCPK10. The results showed that PeCPK10-transgenic lines experienced better growth than vector control plants when treated with drought. Stronger abscisic acid-induced promotion of stomatal closing has been showed in transgenic lines. Particularly, overexpression of PeCPK10 showed enhanced freezing tolerance. Constitutive expression of PeCPK10 enhanced the expression of several abscisic acid-responsive genes and multiple abiotic stress-responsive genes such as RD29B and COR15A. Accordingly, a positive regulator responsive to cold and drought stresses in P. euphratica is proposed.

CDPK1 from ginger promotes salinity and drought stress tolerance without yield penalty by improving growth and photosynthesis in Nicotiana tabacum.

In plants, transient changes in calcium concentrations of cytosol have been observed during stress conditions like high salt, drought, extreme temperature and mechanical disturbances. Calcium-dependent protein kinases (CDPKs) play important roles in relaying these calcium signatures into downstream effects. In this study, a stress-responsive CDPK gene, ZoCDPK1 was isolated from a stress cDNA generated from ginger using rapid amplification of cDNA ends (RLM-RACE) – PCR technique and characterized its role in stress tolerance. An important aspect seen during the analysis of the deduced protein is a rare coupling between the presence of a nuclear localization sequence in the junction domain and consensus sequence in the EF-hand loops of calmodulin-like domain. ZoCDPK1 is abundantly expressed in rhizome and is rapidly induced by high-salt stress, drought, and jasmonic acid treatment but not by low temperature stress or abscissic acid treatment. The sub-cellular localization of ZoCDPK1-GFP fusion protein was studied in transgenic tobacco epidermal cells using confocal laser scanning microscopy. Over-expression of ginger CDPK1 gene in tobacco conferred tolerance to salinity and drought stress as reflected by the high percentage of seed germination, higher relative water content, expression of stress responsive genes, higher leaf chlorophyll content, increased photosynthetic efficiency and other photosynthetic parameters. In addition, transgenic tobacco subjected to salinity/drought stress exhibited 50% more growth during stress conditions as compared to wild type plant during normal conditions. T3 transgenic plants are able to grow to maturity, flowers early and set viable seeds under continuous salinity or drought stress without yield penalty. The ZoCDPK1 up-regulated the expression levels of stress-related genes RD21A and ERD1 in tobacco plants. These results suggest that ZoCDPK1 functions in the positive regulation of the signaling pathways that are involved in the response to salinity and drought stress in ginger and it is likely operating in a DRE/CRT independent manner.

TaCPK2-A, a calcium-dependent protein kinase gene that is required for wheat powdery mildew resistance enhances bacterial blight resistance in transgenic rice

Calcium-dependent protein kinases (CPKs) are important Ca2+ signalling components involved in complex immune and stress signalling networks; but the knowledge of CPK gene functions in the hexaploid wheat is limited. Previously, TaCPK2 was shown to be inducible by powdery mildew (Blumeria graminis tritici, Bgt) infection in wheat. Here, its functions in disease resistance are characterized further. This study shows the presence of defence-response and cold-response cis-elements on the promoters of the A subgenome homoeologue (TaCPK2-A) and D subgenome homoeologue (TaCPK2-D), respectively. Their expression patterns were then confirmed by quantitative real-time PCR (qRT-PCR) using genome-specific primers, where TaCPK2-A was induced by Bgt treatment while TaCPK2-D mainly responded to cold treatment. Downregulation of TaCPK2-A by virus-induced gene silencing (VIGS) causes loss of resistance to Bgt in resistant wheat lines, indicating that TaCPK2-A is required for powdery mildew resistance. Furthermore, overexpression of TaCPK2-A in rice enhanced bacterial blight (Xanthomonas oryzae pv. oryzae, Xoo) resistance. qRT-PCR analysis showed that overexpression of TaCPK2-A in rice promoted the expression of OsWRKY45-1, a transcription factor involved in both fungal and bacterial resistance by regulating jasmonic acid and salicylic acid signalling genes. The opposite effect was found in wheat TaCPK2-A VIGS plants, where the homologue of OsWRKY45-1 was significantly repressed. These data suggest that modulation of WRKY45-1 and associated defence-response genes by CPK2 genes may be the common mechanism for multiple disease resistance in grass species, which may have undergone subfunctionalization in promoters before the formation of hexaploid wheat.