Cold-regulated Genes Research Articles

Effects of low temperature and low irradiance on the physiological characteristics and related gene expression of different pepper species

Pepper is a thermophilous and heliophilic vegetable. In China, pepper is grown in greenhouse during winter and spring under lower temperature and irradiation. In this study, we investigated the effects of low temperature and low irradiance (LTLI) on the physiological characteristics and the expression of related genes in five pepper species, Capsicum annuum L. (CA), C. baccatum L. (CB), C. chinense Jacquin (CC), C. frutescens L. (CF), and C. pubescens Ruiz & Pavon (CP) in order to screen for greenhouse species that is resistant to such adverse conditions. We observed significant reductions not only in photosynthetic pigments and stomatal conductance but also in proline, total soluble sugar, enzyme activity, and root activity; disordered arrangements of leaf palisade and spongy tissues; and first rising and then falling expression of C-repeat binding factor (CBF3) and cold-regulated genes (CORc410). These results indicate that pepper is not resistant to LTLI. We also found that CP showed significantly higher photosynthetic activity, more proline and total soluble sugar, higher enzyme activity, higher root activity, higher CBF3 and CORc410 expression levels, more tightly packed leaf palisade and spongy tissues, and thicker bundle sheath than the other four species did under LTLI, while CF exhibited the lowest values for these indicators. It demonstrated significant differences in the ability to resist to LTLI among different species, with CP showing the strongest resistance, followed by CB. Therefore, we recommend the introduction of CP and CB to greenhouse cultivation to further screen for low temperature and low light-resistant pepper varieties to increase pepper production by strengthening intervariety hybridization.

Cold acclimation induces distinctive changes in the chromatin state and transcript levels of COR genes in Cannabis sativa varieties with contrasting cold acclimation capacities.

Little is known about the capacity of Cannabis sativa to cold-acclimate and develop freezing tolerance. This study investigates the cold acclimation (CA) capacity of nine C. sativa varieties and the underlying genetic and epigenetic responses. The varieties were divided into three groups based on their contrasting CA capacities by comparing the survival of non-acclimated and cold-acclimated plants in whole-plant freeze tests. In response to the CA treatment, all varieties accumulated soluble sugars but only the varieties with superior capacity for CA could maintain higher levels throughout the treatment. In addition, the varieties that acclimated most efficiently accumulated higher transcript levels of cold-regulated (COR) genes and genes involved in de novo DNA methylation while displaying locus- and variety-specific changes in the levels of H3K9ac, H3K27me3 and methylcytosine (MeC) during CA. Furthermore, these hardy C. sativa varieties displayed significant increases in MeC levels at COR gene loci when deacclimated, suggesting a role for locus-specific DNA methylation in deacclimation. This study uncovers the molecular mechanisms underlying CA in C. sativa and reveals higher levels of complexity regarding how genetic, epigenetic and environmental factors intertwine.

The receptor kinase IMPAIRED OOMYCETE SUSCEPTIBILITY1 attenuates abscisic acid responses in Arabidopsis.

In plants, membrane-bound receptor kinases are essential for developmental processes, immune responses to pathogens and the establishment of symbiosis. We previously identified the Arabidopsis (Arabidopsis thaliana) receptor kinase IMPAIRED OOMYCETE SUSCEPTIBILITY1 (IOS1) as required for successful infection with the downy mildew pathogen Hyaloperonospora arabidopsidis. We report here that IOS1 is also required for full susceptibility of Arabidopsis to unrelated (hemi)biotrophic filamentous oomycete and fungal pathogens. Impaired susceptibility in the absence of IOS1 appeared to be independent of plant defense mechanism. Instead, we found that ios1-1 plants were hypersensitive to the plant hormone abscisic acid (ABA), displaying enhanced ABA-mediated inhibition of seed germination, root elongation, and stomatal opening. These findings suggest that IOS1 negatively regulates ABA signaling in Arabidopsis. The expression of ABA-sensitive COLD REGULATED and RESISTANCE TO DESICCATION genes was diminished in Arabidopsis during infection. This effect on ABA signaling was alleviated in the ios1-1 mutant background. Accordingly, ABA-insensitive and ABA-hypersensitive mutants were more susceptible and resistant to oomycete infection, respectively, showing that the intensity of ABA signaling affects the outcome of downy mildew disease. Taken together, our findings suggest that filamentous (hemi)biotrophs attenuate ABA signaling in Arabidopsis during the infection process and that IOS1 participates in this pathogen-mediated reprogramming of the host.

Over-expression of miR397 improves plant tolerance to cold stress in Arabidopsis thaliana

Cold stress is an environmental factor that limits the geographical distribution and growing season of plants. The plant response to cold involves different metabolic pathways and gene regulation. Although the expression of some miRNAs is significantly altered in cold stress, little is known about the regulatory function of miRNAs in plant resistance to cold. In this study, we generated transgenic Arabidopsis plants which harbor an over-expression construct of 35S::miR397a. Analysis by RNA blotting revealed high levels of miR397a transcripts in the transformed plants. Plant cold tolerance assays demonstrated that over-expression of miR397a improved plant tolerance to chilling and freezing stresses. In addition, this study showed that the freezing tolerance of miR397a-ov plants was improved by cold acclimation at 4°C. Northern blot analysis revealed that overexpression of miR397a affected the expression of coldregulated CBF genes and downstream COR genes. These findings provide evidence demonstrating a regulatory role of miR397 in the cold signaling pathway and plant tolerance to chilling and freezing stresses.

Cold response in Phalaenopsis aphrodite and characterization of PaCBF1 and PaICE1.

Phalaenopsis is a winter-blooming orchid genus commonly cultivated in tropical Asian countries. Because orchids are one of the most economically important flower crops in Taiwan, it is crucial to understand their response to cold and other abiotic stresses. The present study focused on gene regulation of P. aphrodite in response to abiotic stress, mainly cold. Our results demonstrate that P. aphrodite is sensitive to low temperatures, especially in its reproductive stage. We found that after exposure to 4°C, plants in the vegetative stage maintained better membrane integrity and photosynthetic capacity than in the flowering stage. At the molecular level, C-repeat binding factor1 (PaCBF1) and its putative target gene dehydrin1 (PaDHN1) mRNAs were induced by cold, whereas inducer of CBF expression1 (PaICE1) mRNA was constitutively expressed. PaICE1 transactivated MYC motifs in the PaCBF1 promoter, indicating that up-regulation of PaCBF1 may be mediated by the binding of PaICE1 to MYC motifs. Overexpression of PaCBF1 in transgenic Arabidopsis induced AtCOR6.6 and RD29a without cold stimulus and maintained better membrane integrity after cold stress. Herein, we present evidence that cold induction of PaCBF1 transcripts in P. aphrodite may be transactivated by PaICE1 and consequently protect plants from cold damage through up-regulation of cold-regulated (COR) genes, such as DHN. To our knowledge, this study is the first report of the isolation and characterization of CBF, DHN and ICE genes in the Orchidaceae family.

New clues for a cold case: nitric oxide response to low temperature

Low temperature is among the most frequent stresses met by plants during their lifespan, and a plant's ability to cold-acclimate is a determinant for further growth and development. Although intensive research has provided a good picture of the molecular and metabolic changes triggered by cold, the underlying regulatory mechanisms remain elusive and are thus being actively sought. Recent studies have shed light on the importance of nitric oxide (NO), a ubiquitous signalling molecule in eukaryotes, for plant tolerance to chilling and freezing. Indeed, NO formation following cold exposure has been reported in a range of plant species, and a series of proteins targeted by NO-based post-translational modifications have been identified. Moreover, key cold-regulated genes have been characterized as NO-dependent, suggesting the crucial importance of NO signalling for cold-responsive gene expression. This review provides a picture of our current understanding of the function of NO in the context of plant response to cold. Particular attention is dedicated to the open questions left by the fragmented data currently available concerning NO formation, transduction and biological significance for plant adaptation to low temperature.

The expression of CBF genes at Fr-2 locus is associated with the level of frost tolerance in Bulgarian winter wheat cultivars

The regulation of the majority of cold-regulated genes in plants is mediated by CBF (C-repeat binding factors) transcription factor family. Natural differences in frost tolerance (FT) of wheat have been mapped to the Fr-2 (Frost Resistance-2) locus on chromosome group 5 and are associated with variation in threshold induction temperatures and/or transcript levels of CBF genes.

Copy number and haplotype variation at the VRN-A1 and central FR-A2 loci are associated with frost tolerance in hexaploid wheat.

The interaction between VRN - A1 and FR - A2 largely affect the frost tolerance of hexaploid wheat. Frost tolerance is critical for wheat survival during cold winters. Natural variation for this trait is mainly associated with allelic differences at the VERNALIZATION 1 (VRN1) and FROST RESISTANCE 2 (FR2) loci. VRN1 regulates the transition between vegetative and reproductive stages and FR2, a locus including several tandemly duplicated C-REPEAT BINDING FACTOR (CBF) transcription factors, regulates the expression of Cold-regulated genes. We identified sequence and copy number variation at these two loci among winter and spring wheat varieties and characterized their association with frost tolerance. We identified two FR-A2 haplotypes-'FR-A2-S' and 'FR-A2-T'-distinguished by two insertion/deletions and ten single nucleotide polymorphisms within the CBF-A12 and CBF-A15 genes. Increased copy number of CBF-A14 was frequently associated with the FR-A2-T haplotype and with higher CBF14 transcript levels in response to cold. Factorial ANOVAs revealed significant interactions between VRN1 and FR-A2 for frost tolerance in both winter and spring panels suggesting a crosstalk between vernalization and cold acclimation pathways. The model including these two loci and their interaction explained 32.0 and 20.7 % of the variation in frost tolerance in the winter and spring panels, respectively. The interaction was validated in a winter wheat F 4:5 population segregating for both genes. Increased VRN-A1 copy number was associated with improved frost tolerance among varieties carrying the FR-A2-T allele but not among those carrying the FR-A2-S allele. These results suggest that selection of varieties carrying the FR-A2-T allele and three copies of the recessive vrn-A1 allele would be a good strategy to improve frost tolerance in wheat.

Genomics of Cold Hardiness in Woody Plants

The term cold hardiness or freezing tolerance is used to represent, in a general sense, the ability of plants to adapt to and withstand freezing temperatures. It is a complex, multigenic trait that is too often viewed as a single entity when in fact it is composed of many aspects, all of which can be to some extent viewed as genetically distinct. Advances in molecular biology and genomics have provided significant advances in understanding how plants respond to low temperature and acquire freezing tolerance. Among the most important discoveries has been the identification of the CBF/DREB transcription factor. This transcription factor, along with its regulators such as ICE transcription factors, play a major role in sensing low temperature, initiating the process of cold acclimation, and inducing the expression of a large set of cold-regulated genes. These latter genes are presumed to ameliorate injury to plant cells as a result of freeze-induced desiccation and the presence of extracellular ice. The present review provides a comprehensive overview of CBF and ICE genes in a number of woody plants whose genomes have been sequenced and provides information on the attempts to identify genetic markers for use in marker-assisted selection (MAS) or to improve cold hardiness using genetic transformation technologies. Functional studies of CBF genes in woody plants have indicated that their regulation and impact on abiotic stress resistance are more complex than in herbaceous plants. In particular, the possible relationship of CBF to dormancy is highlighted. Cold hardiness is a complex trait and the challenge in the future will be to use the molecular and genetic tools that are being developed, as well as new developments in bioinformatics, to integrate complex sets of data into a systems view of plant biology. This approach holds the best promise for developing the ability to significantly improve cold hardiness in economically important crops while still maintaining high levels of plant productivity and yield.

Comparative analysis of alternative splicing, alternative polyadenylation and the expression of the two KIN genes from cytoplasmic male sterility cabbage (Brassica oleracea L. var. capitata L.)

The KIN genes are crucial members of the cold-regulated gene family. They play exclusive roles during the developmental processes of many organs and respond to various abiotic stresses in plants. However, little is known about the regulation of KIN gene expression in cytoplasmic male sterility (CMS) cabbages (Brassica oleracea L. var. capitata L.). We carried out a genome-wide analysis to identify the KIN genes in the CMS cabbage. Two non-redundant KIN genes, named BoKIN1 (Bol021262) and BoKIN2 (Bol030498), were identified. Reverse transcriptase PCR detected alternative splicing (AS) products of BoKIN1 (four AS products) and BoKIN2 (three AS products). In addition, alternative polyadenylation (APA) was observed for BoKIN1 and BoKIN2 in the CMS cabbage, resulting in variable 3'UTRs in their transcripts. Furthermore, the transcription levels of BoKIN1-0 and BoKIN2-0, the introns of which were spliced completely, were analyzed in various organs and young leaves treated by abiotic stresses. Our data indicated that BoKIN1-0 is highly expressed in various organs, whereas BoKIN2-0 is expressed exclusively in the stamen. Our study also suggested that BoKIN1-0 was upregulated significantly in young leaves of plants exposed to abscisic acid treatment, and cold and heat stress. BoKIN1 and BoKIN2 had differential AS and APA patterns in pre-mRNA processing, and showed differences in their expression patterns and transcript levels. BoKIN1 participates widely in organ development and responds to diverse abiotic stresses, whereas BoKIN2 plays a main role in stamen development in the CMS cabbage.

Molecular and functional characterization of cold-responsive C-repeat binding factors from Brachypodium distachyon

BackgroundAdverse environmental conditions severely influence various aspects of plant growth and developmental processes, causing worldwide reduction of crop yields. The C-repeat binding factors (CBFs) are critical transcription factors constituting the gene regulatory network that mediates the acclimation process to low temperatures. They regulate a large number of cold-responsive genes, including COLD-REGULATED (COR) genes, via the CBF-COR regulon. Recent studies have shown that the CBF transcription factors also play a role in plant responses to drought and salt stresses. Putative CBF gene homologues and their downstream genes are also present in the genome of Brachypodium distachyon, which is perceived as a monocot model in recent years. However, they have not been functionally characterized at the molecular level.ResultsThree CBF genes that are responsive to cold were identified from Brachypodium, designated BdCBF1, BdCBF2, and BdCBF3, and they were functionally characterized by molecular biological and transgenic approaches in Brachypodium and Arabidopsis thaliana. Our results demonstrate that the BdCBF genes contribute to the tolerance response of Brachypodium to cold, drought, and salt stresses by regulating downstream targets, such as DEHYDRIN5.1 (Dhn5.1) and COR genes. The BdCBF genes are induced under the environmental stress conditions. The BdCBF proteins possess transcriptional activation activity and bind directly to the promoters of the target genes. Transgenic Brachypodium plants overexpressing the BdCBF genes exhibited enhanced resistance to drought and salt stresses as well as low temperatures, and accordingly endogenous contents of proline and soluble sugars were significantly elevated in the transgenic plants. The BdCBF transcription factors are also functional in the heterologous system Arabidopsis. Transgenic Arabidopsis plants overexpressing the BdCBF genes were also tolerant to freezing, drought, and salt stresses, and a set of stress-responsive genes was upregulated in the transgenic Arabidopsis plants.ConclusionsTaken together, our results strongly support that the BdCBF transcription factors are key regulators of cold stress responses in Brachypodium and the CBF-mediated cold stress signaling pathway is conserved in this plant species. We believe that this study would confer great impact on stress biology in monocot species and could be applied to engineer abiotic stress tolerance of bioenergy grass species.

The Arabidopsis Mediator Complex Subunits MED16, MED14, and MED2 Regulate Mediator and RNA Polymerase II Recruitment to CBF-Responsive Cold-Regulated Genes

The Mediator16 (MED16; formerly termed SENSITIVE TO FREEZING6 [SFR6]) subunit of the plant Mediator transcriptional coactivator complex regulates cold-responsive gene expression in Arabidopsis thaliana, acting downstream of the C-repeat binding factor (CBF) transcription factors to recruit the core Mediator complex to cold-regulated genes. Here, we use loss-of-function mutants to show that RNA polymerase II recruitment to CBF-responsive cold-regulated genes requires MED16, MED2, and MED14 subunits. Transcription of genes known to be regulated via CBFs binding to the C-repeat motif/drought-responsive element promoter motif requires all three Mediator subunits, as does cold acclimation-induced freezing tolerance. In addition, these three subunits are required for low temperature-induced expression of some other, but not all, cold-responsive genes, including genes that are not known targets of CBFs. Genes inducible by darkness also required MED16 but required a different combination of Mediator subunits for their expression than the genes induced by cold. Together, our data illustrate that plants control transcription of specific genes through the action of subsets of Mediator subunits; the specific combination defined by the nature of the stimulus but also by the identity of the gene induced.

COR-Like Gene Is Involved in Induced-Expression Response to Multiple Abiotic Stresses in Grape Vine (<i>Vitis amurensis</i>) Tissues

Cold stress, which causes dehydration damage to plants, is one of the most common abiotic stresses that limit plant distributions and affect crop growth and development. To improve their cold tolerance, plants often upregulate the expression of some cold-related genes. In this study, a cold-regulated (COR) gene was isolated from Vitis amurensis and designated as VaCOR. RT-PCR analysis demonstrated that VaCOR was expressed at high levels in the roots, stems, leaves, and petioles under low temperature, but it was not detected under normal temperatures. Further analysis revealed that salinity and the application of exogenous abscisic acid and salicylic acid significantly induced VaCOR transcription, with apparent differences in its expression in different organs. The data also showed that COR gene expression was higher in cold-resistant wild V. amurensis than in cold-sensitive Vitis vinifera “Manicure Finger” under low temperature. These results suggest that the VaCOR gene in V. amurensis grapes is involved in multiple stresses and plays a central role in stress-induced and stress-tolerance.

Nonsense-mediated decay of sucrose synthase 1 mRNA with induced premature chain termination codon during cold acclimation in winter wheat

Cold acclimation induces the expression of cold-regulated genes needed to protect plants against freezing damage. Fourteen candidate genes were identified as being differentially expressed (presence/absence) between cold acclimated and nonacclimated crown and leaf tissues of 2 winter wheat lines using the cDNA-AFLP method. Two TILLING populations originating from the 2 winter wheat lines were further developed in order to create mutant forms of the candidate genes to verify their role in freezing-tolerance formation. Exon 8 of the identified differentially expressed sucrose synthase 1 (Ss1) gene was chosen for mutation detection by high-resolution melting analysis. A total of 75.68 kb of DNA was screened and 2 novel alleles of the Ss1 gene were identified, of which 1 was silent and 1 was a nonsense (premature stop codon) mutation. qRT-PCR analysis showed that premature stop codon mutation has a strong negative effect on Ss1 gene expression in nonacclimated leaves as well as in crowns and leaves collected at 2, 4, and 6 weeks of cold acclimation compared with the wild-type winter wheat line. Further work will reveal the effect of the mutation on cold tolerance of winter wheat and will enable the assessment of the role of Ss1 in the cold acclimation process.

Strength comparison between cold-inducible promoters of Arabidopsis cor15a and cor15b genes in potato and tobacco

The cold-inducible promoter is ideal for regulating ectopic gene expression in plants to cope with the cold stress. The promoters of two cold-regulated genes, cor15a and cor15b, were cloned from Arabidopsis thaliana and their strengths were assayed in potato and tobacco. Although the cis-element composition and cold-inducible property were similar between the two promoters, the cor15b promoter showed significantly higher activity than the cor15a promoter in both potato and tobacco. In order to elucidate the factors determining this discrepancy, cor15a and cor15b promoters were separately truncated from 5'-end to construct short promoters with similar size containing a single C-repeat/dehydration-responsive element (CRT/DRE). Subsequently, two synthetic promoters were constructed by swapping the flanking sequences of CRT/DRE in the truncated promoters. The promoter strength comparison demonstrated that the flanking sequence could affect the promoter strength. These findings provide a potential regulatory mechanism to control the promoter strength without impact on other properties.

Role of CBFs as Integrators of Chloroplast Redox, Phytochrome and Plant Hormone Signaling during Cold Acclimation

Cold acclimation of winter cereals and other winter hardy species is a prerequisite to increase subsequent freezing tolerance. Low temperatures upregulate the expression of C-repeat/dehydration-responsive element binding transcription factors (CBF/DREB1) which in turn induce the expression of COLD-REGULATED (COR) genes. We summarize evidence which indicates that the integration of these interactions is responsible for the dwarf phenotype and enhanced photosynthetic performance associated with cold-acclimated and CBF-overexpressing plants. Plants overexpressing CBFs but grown at warm temperatures mimic the cold-tolerant, dwarf, compact phenotype; increased photosynthetic performance; and biomass accumulation typically associated with cold-acclimated plants. In this review, we propose a model whereby the cold acclimation signal is perceived by plants through an integration of low temperature and changes in light intensity, as well as changes in light quality. Such integration leads to the activation of the CBF-regulon and subsequent upregulation of COR gene and GA 2-oxidase (GA2ox) expression which results in a dwarf phenotype coupled with increased freezing tolerance and enhanced photosynthetic performance. We conclude that, due to their photoautotrophic nature, plants do not rely on a single low temperature sensor, but integrate changes in light intensity, light quality, and membrane viscosity in order to establish the cold-acclimated state. CBFs appear to act as master regulators of these interconnecting sensing/signaling pathways.

Natural variation of C‐repeat‐binding factor (CBFs) genes is a major cause of divergence in freezing tolerance among a group of Arabidopsis thaliana populations along the Yangtze River in China

We used a monophyletic group of four natural populations of Arabidopsis thaliana expanded from a single ancestor along the Yangtze River c. 90,000 yr ago to study the molecular mechanism of the divergence in their freezing tolerance, in order to gain an insight into the genetic basis of their local adaption to low temperatures. Freezing tolerance assays, measurements of metabolites in the raffinose biosynthesis pathway and transactivation-activity assays of variation in forms of cold-responsive transcription factors were conducted on the four populations. Quantitative trait locus mapping was adopted with F₂ populations of the most- and least freezing-tolerant populations. The degree of freezing tolerance among the four populations was negatively correlated with the lowest monthly average temperature of January in their native habitats, and positively correlated to the expression level of some cold-regulated genes. We identified a major locus harboring three cold-responsive transcription factor genes CBF1-3, and found a nucleotide insertion in CBF2 in all populations except SXcgx, which generated a dysfunctional CBF2 protein. The CBF2 in SXcgx experienced a stronger natural selection in the cooler environment after CBF3 lost its response to low temperature, which possibly reflects a local adaptation of these populations during the expansion from a common ancestor.

Molecular switch for cold acclimation — anatomy of the cold-inducible promoter in plants

In plants, a promoter is essential to drive the transcription and expression of genes under stress conditions. The cold-regulated promoter is an important molecular switch involved in transcriptional regulation of a dynamic network of genes associated with cold acclimation processes. However, the structure and functions of the cold-regulated promoter are ambiguous. In this review, we first describe the common type and structures of the cold-regulated promoter, such as the core promoter and transcription factor binding sites, and then discuss the synergistic actions of promoter elements and cold-regulated genes. We also describe the transcriptional responses and cross-talk among cold-regulated genes in the ICE-CBF-COR cold-response pathway. Many stress-inducible genes are known to be regulated by endogenous abscisic acid (ABA), which accumulates during osmotic and cold stress. We discuss the regulation of promoters of cold-inducible genes in ABA-dependent and ABA-independent regulatory systems. We also describe the cross-talk among gene networks regulated by different cis-acting regulatory elements. Finally, we propose potential further research on, and practical applications of, the cold-regulated promoter.

Wheat CBF gene family: identification of polymorphisms in the CBF coding sequence

Expression of cold-regulated genes needed for protection against freezing stress is mediated, in part, by the CBF transcription factor family. Previous studies with temperate cereals suggested that the CBF gene family in wheat was large, and that CBF genes were at the base of an important low temperature tolerance trait. Therefore, the goal of our study was to identify the CBF repertoire in the freezing-tolerant hexaploid wheat cultivar Norstar, and then to examine if the coding region of CBF genes in two spring cultivars contain polymorphisms that could affect the protein sequence and structure. Our analyses reveal that hexaploid wheat contains a complex CBF family consisting of at least 65 CBF genes of which 60 are known to be expressed in the cultivar Norstar. They represent 27 paralogous genes with 1-3 homeologous copies for the A, B, and D genomes. The cultivar Norstar contains two pseudogenes and at least 24 additional proteins having sequences and (or) structures that deviate from the consensus in the conserved AP2 DNA-binding and (or) C-terminal activation-domains. This suggests that in cultivars such as Norstar, low temperature tolerance may be increased through breeding of additional optimal alleles. The examination of the CBF repertoire present in the two spring cultivars, Chinese Spring and Manitou, reveals that they have additional polymorphisms affecting conserved positions in these domains. Understanding the effects of these polymorphisms will provide additional information for the selection of optimum CBF alleles in Triticeae breeding programs.

Characterization of the variable 3′ UTR and expression of the two intron-containing KIN transcripts from Capsella bursa-pastoris

KIN genes are crucial members of the cold-regulated (COR) gene family, and are exclusively involved in normal developmental processes in many organs and respond to a variety of abiotic stresses in plants. Here, we cloned and sequenced not only two completely-spliced KIN transcripts (CbKIN1-S and CbKIN2-S), but also two intron-containing KIN transcripts (CbKIN1-U and CbKIN2-U), from Capsella bursa-pastoris, a widespread plant of the Brassicaceae family. The CbKIN1-U and CbKIN2-U transcripts each contained one additional intron in the coding region compared to the corresponding CbKIN1-S and CbKIN2-S transcripts. In addition, the two intron-containing KIN transcripts were found by rapid amplification of cDNA 3′ ends (3′ RACE) analysis with specific primers to have variable 3′ untranslated regions (3′ UTRs). We also analyzed CbKIN1-U and CbKIN2-U levels in different organs and embryonic stages by quantitative polymerase chain reaction (qPCR). They were found to be expressed in middle-stage embryos and flowers. After abscisic acid (ABA) treatment, CbKIN1-U and CbKIN2-U showed strong responses in young leaves and weak responses in flowers. Levels of the two intron-containing KIN transcripts were markedly increased in young leaves when plants were exposed to cold and heat stress. Both of them showed stronger responses to ABA treatment and cold stress than that to heat stress. CbKIN1-U and CbKIN2-U share similar gene expression profiles in development and in response to exposure to different stresses, suggesting that they probably play similar biological roles in C. bursa-pastoris.