NAC Genes Research Articles

Overexpression of a novel NAC-type tomato transcription factor, SlNAM1, enhances the chilling stress tolerance of transgenic tobacco

The NAC proteins are the largest transcription factors in plants. The functions of NACs are various and we focus on their roles in response to abiotic stress here. In our study, a typical NAC gene (SlNAM1) is isolated from tomato and its product is located in the nucleus. It also has a transcriptional activity region situated in C-terminal. The expression levels of SlNAM1 in tomato were induced by 4°C, PEG, NaCl, abscisic acid (ABA) and methyl jasmonate (MeJA) treatments. The function of SlNAM1 in response to chilling stress has been investigated. SlNAM1 overexpression in tobacco exhibited higher germination rates, minor wilting, and higher photosynthetic rates (Pn) under chilling stress. Meanwhile, overexpression of SlNAM1 improved the osmolytes contents and reduced the H2O2 and O2⿢⿿ contents under low temperature, which contribute to alleviating the oxidative damage of cell membrane after chilling stress. Moreover, the transcripts of NtDREB1, NtP5CS, and NtERD10s were higher in transgenic tobacco, and those increased expressions may confer higher chilling tolerance of transgenic plants. These results indicated that overexpression of SlNAM1 could improve chilling stress tolerance of transgenic tobacco.

Mutation of Rice Early Flowering3.1 (OsELF3.1) delays leaf senescence in rice.

In Arabidopsis, EARLY FLOWERING3 (ELF3) has pivotal roles in controlling circadian rhythm and photoperiodic flowering. In addition, ELF3 negatively regulates leaf senescence by repressing the transcription of PHYTOCHROME-INTERACTING FACTOR4 (PIF4) and PHYTOCHROME-INTERACTING FACTOR5 (PIF5); elf3 mutants senesce earlier and ELF3-overexpressing (ELF3-OX) plants senesce later than wild type (WT). Here, we show that in contrast to Arabidopsis ELF3, which represses senescence, the rice homolog OsELF3.1 promotes leaf senescence; oself3.1 mutants showed delayed senescence and OsELF3.1-OX plants senesced earlier under both dark-induced and natural senescence conditions. Microarray analysis revealed that in the senescing leaves, a number of senescence-associated genes, phytohormone-related genes, and NAC and WRKY family genes (OsNAP, ONAC106, and OsWRKY42) were differentially expressed in oself3.1 mutants compared with WT. Interestingly, we found that Arabidopsis plants overexpressing OsELF3.1 show delayed leaf senescence, produce short petioles, and flower late in long days, just like Arabidopsis ELF3-OX plants. This demonstrates that the regulatory functions of ELF3 and OsELF3.1 are conserved between Arabidopsis and rice, but the downstream regulatory cascades have opposite effects.

A stress-associated NAC transcription factor (SlNAC35) from tomato plays a positive role in biotic and abiotic stresses.

The NAC transcription factor family participates in responses to various kinds of environmental stimuli in plants. Responses of NAC genes to abiotic stresses have been widely studied, but their functions in response to biotic stress are little reported in plants, especially in crops. In the present study, we examined the functions of a novel tomato (Solanum lycopersicum) NAC protein (SlNAC35) in abiotic and biotic stress resistance by using transgenic tobacco. Expression analysis found that SlNAC35 expression was induced by drought stress, salt stress, bacterial pathogen, and signaling molecules, suggesting its involvement in plant responses to biotic and abiotic stimuli. Moreover, transgenic lines exhibited a greater number of lateral roots and longer root length compared with Vec lines (empty vector lines) after drought and salt treatment. These results indicate that overexpression of SlNAC35 promoted root growth and development under drought and salt stresses. Higher expressions of NtARF1, NtARF2 and NtARF8 were observed under drought and salt stresses in transgenic lines, suggesting that overexpression of SlNAC35 promoted growth and development of roots in transgenic lines possibly by involving auxin signaling and by regulating NtARF expression. In addition, SlNAC35 overexpression improved resistance to bacterial pathogen in transgenic tobacco, and reactive oxygen species may be in the upstream of salicylic acid (SA) signaling in transgenic tobacco during defense response.

Identification of an NAC Transcription Factor Family by Deep Transcriptome Sequencing in Onion (Allium cepa L.).

Although onion has been used extensively in the past for cytogenetic studies, molecular analysis has been lacking because the availability of genetic resources is limited. NAM, ATAF, and CUC (NAC) transcription factors (TFs) are plant-specific proteins, and they play key roles in plant growth, development, and stress tolerance. However, none of the onion NAC (CepNAC) genes had been identified thus far. In this study, the transcriptome of onion leaves was analyzed by Illumina paired-end sequencing. Approximately 102.9 million clean sequence reads were produced and used for de novo assembly, which generated 117,189 non-redundant transcripts. Of these transcripts, 39,472 were annotated for their function. In order to mine the CepNAC TFs, CepNAC genes were searched from the transcripts assembled, resulting in the identification of all 39 CepNAC genes. These 39 CepNAC proteins were subjected to phylogenetic analysis together with 47 NAC proteins of known function that were previously identified in other species. The results showed that they can be divided into five groups (NAC-I–V). Interestingly, the NAC-IV and -V groups were found to be likely related to the processes of secondary wall synthesis and stress response, respectively. The transcriptome analysis generated a substantial amount of transcripts, which will aid immensely in identifying important genes and accelerating our understanding of onion growth and development. Moreover, the discovery of 39 CepNAC TFs and the identification of the sequence conservation between them and NAC proteins published will provide a basis for further characterization and validation of their functions in the future.

Functional characterization of NAC55 transcription factor from oilseed rape (Brassica napus L.) as a novel transcriptional activator modulating reactive oxygen species accumulation and cell death.

NAC transcription factors (TFs) are plant-specific and play important roles in development, responses to biotic and abiotic cues and hormone signaling. So far, only a few NAC genes have been reported to regulate cell death. In this study, we identified and characterized a NAC55 gene isolated from oilseed rape (Brassica napus L.). BnaNAC55 responds to multiple stresses, including cold, heat, abscisic acid (ABA), jasmonic acid (JA) and a necrotrophic fungal pathogen Sclerotinia sclerotiorum. BnaNAC55 has transactivation activity and is located in the nucleus. BnaNAC55 is able to form homodimers in planta. Unlike ANAC055, full-length BnaNAC55, but not either the N-terminal NAC domain or C-terminal regulatory domain, induces ROS accumulation and hypersensitive response (HR)-like cell death when expressed both in oilseed rape protoplasts and Nicotiana benthamiana. Furthermore, BnaNAC55 expression causes obvious nuclear DNA fragmentation. Moreover, quantitative reverse transcription PCR (qRT-PCR) analysis identified that the expression levels of multiple genes regulating ROS production and scavenging, defense response as well as senescence are significantly induced. Using a dual luciferase reporter assay, we further confirm that BnaNAC55 could activate the expression of a few ROS and defense-related gene expression. Taken together, our work has identified a novel NAC TF from oilseed rape that modulates ROS accumulation and cell death.

English

GhNAC18 is a novel NAC gene that was isolated from cotton (Gossypium hirsutum L.). The full-length cDNA was 1511 bp including an open reading frame of 1260 bp in length and encodes a protein of 419 amino acids. With qRT-PCR analysis, GhNAC18 was downregulated during natural and dark-induced senescence, implicating this gene as anti-aging gene in cotton. Analysis of its promoter revealed a group of putative cis-acting elements especially, the light and stress responsive elements, indicating that it may have a potential role in leaf development. Additionally, GhNAC18 was found to have transcriptional activation activities on its C-terminal region and by bioinformatics analysis, GhNAC18 was localized in the nucleus. Tissue specific expression analysis indicated that GhNAC18 is constitutively expressed in roots, stems, earlier stages of senescing leaves, fibers and flower parts with high expression levels registered in the young leaves and cotyledon leaves. GhNAC18 was up-regulated by exogenous application of various phytohormones including salicylic acid (SA), methyl Jasmonate (MeJA) and ethylene (ET) but downregulated with abscisic acid (ABA).  Moreover, the gene was induced by drought (PEG6000), H2O2, cold (4°C) and wounding but was inhibited by high salinity. These results indicated that GhNAC18 is a transcriptional activator that is involved in leaf development, especially inhibition of leaf senescence and plant stress responses in cotton. This study provides fundamental information on understanding the function of GhNAC18 gene in cotton leaf senescence and stress tolerance and thereafter its manipulation for breeding of  late-aging and  stress-tolerant cultivars. Key words: GhNAC18, stress response, senescence, Gossypium hirsutum L. NAC.

Identification and characterization of a novel NAC-like gene in chrysanthemum (Dendranthema lavandulifolium).

A NAC -like gene named DlNAC1 was identified in chrysanthemum and characterized; it may be involved in regulation of response to abiotic stressors, especially in tolerance to drought and salinity. NAC transcription factors in plants play crucial roles in tolerance to abiotic stressors, and overexpression of the NAC gene in Arabidopsis has been demonstrated to lead to improved drought tolerance. Functions of the NAC genes in chrysanthemum, however, remain poorly understood. In this study, a NAC-like gene named DlNAC1 was identified in chrysanthemum (Dendranthema lavandulifolium) and characterized. Phylogenetic analysis indicated that DlNAC1 contains a typical NAC domain and belongs to the ONAC022 subgroup. According to the subcellular localization and yeast one-hybrid assay, the DlNAC1 protein is localized to nuclei and has a transcription activation ability. Moreover, quantitative real-time PCR analyses showed that DlNAC1 was induced by low-temperature, high-salinity, and drought conditions (separately), but not by abscisic acid (ABA) and heat shock. In these experiments, the downstream genes of NAC transcription factors were found to be up-regulated, including stress-responsive genes KIN1 and AMY1. To further explore the effects of DlNAC1 in response to abiotic stressors, DlNAC1 was overexpressed in tobacco, and these transgenic plants showed significantly enhanced tolerance to drought and salinity. This study suggests that in chrysanthemum, the DlNAC1 gene is involved in regulation of the response to abiotic stressors, especially in tolerance to drought and salinity.

Genome-wide investigation of the NAC transcription factor family in melon (Cucumis melo L.) and their expression analysis under salt stress.

82 melon NAC (CmNAC) genes were identified in melon. We putatively identified the function of CmNAC gene in melon under salt stress. NAC transcription factor proteins play important roles in many biological processes, including plant development and stress responses. To date, few full-length melon NAC proteins have been identified. In this study, 82 melon NAC (CmNAC) genes were identified in the Cucumis melo L. genome. By interrogating our cDNA libraries and transcriptome data from melon under salt stress, and comparison of their phylogenetic relationship with Arabidopsis NAC salt stress-related genes, we putatively identified that the fourth clade of CmNAC genes were involved in the salt stress response, especially the second clade of the group IV of the phylogenetic tree. Expression analysis confirmed that eleven of the twelve CmNAC genes from the group IV were induced in melon seedling roots by salt stress; the other gene was down regulated by salt stress. The expression of CmNAC14 continually increased in 12h under salt stress, and was selected for transformation into Arabidopsis for functional verification. Overexpression of CmNAC14 increased the sensitivity of transgenic Arabidopsis lines to salt stress, which were simultaneously demonstrated by reduced expression of abiotic stress-response genes and variation in several physiological indices. This study increases our knowledge and may enable further characterization of the roles of CmNAC family in the response to salt stress.

Identification and functional characterization of the NAC gene promoter from Populus euphratica.

The PeNAC1 promoter is a non-tissue-specific and stress-inducible promoter containing a GA-responsive element and a MYB recognition sequence that are responsible for induced expression patterns. NAC transcription factors play vital roles in complex signaling networks during plant stress responses. Promoters as crucial molecular switches are involved in the transcriptional regulation of gene activities dynamic network controlling a variety of biological processes, such as developmental processes, responses to hormone and abiotic stress. In this study, a 1217-bp flanking fragment of the stress-responsive NAC gene PeNAC1 was isolated from Populus euphratica. In transgenic Arabidopsis, this promoter fragment was found to have a higher activity than the cauliflower mosaic virus 35S promoter and remained active throughout the plant life cycle, particularly in the spiral vessels and cortical cells of vascular tissues of various organs. We identified a gibberellic acid-responsive element, required for response to gibberellic acid and involved in the salt-stress signaling pathway, and a MYB recognition sequence, which has an important role in promoter response to drought stress, in the PeNAC1 promoter. These results suggest that the PeNAC1 promoter is more effective, non-tissue-specific, and inducible. In addition, the presence of a putative NAC protein-binding motif in the PeNAC1 promoter indicates that PeNAC1 is either regulated by other NAC transcription factors or is self-regulated. Our research will help reveal the regulatory mechanism of the upstream region of the PeNAC1 gene and provide a foundation for the use of the PeNAC1 promoter in molecular breeding.

ZmNAC55, a maize stress-responsive NAC transcription factor, confers drought resistance in transgenic Arabidopsis

Abiotic stress has been shown to significantly limit the growth and productivity of crops. NAC transcription factors play essential roles in response to various abiotic stresses. However, only little information regarding stress-related NAC genes is available in maize. Here, we cloned a maize NAC transcription factor ZmNAC55 and identified its function in drought stress. Transient expression and transactivation assay demonstrated that ZmNAC55 was localized in the nucleus and had transactivation activity. Expression analysis of ZmNAC55 in maize showed that this gene was induced by drought, high salinity and cold stresses and by abscisic acid (ABA). Promoter analysis demonstrated that multiple stress-related cis-acting elements exist in promoter region of ZmNAC55. Overexpression of ZmNAC55 in Arabidopsis led to hypersensitivity to ABA at the germination stage, but enhanced drought resistence compared to wild-type seedlings. Transcriptome analysis identified a number of differentially expressed genes between 35S::ZmNAC55 transgenic and wild-type plants, and many of which are involved in stress response, including twelve qRT–PCR confirmed well-known drought-responsive genes. These results highlight the important role of ZmNAC55 in positive regulates of drought resistence, and may have potential applications in transgenic breeding of drought-tolerant crops.

Genome-wide analysis, expression dynamics and varietal comparison of NAC gene family at various developmental stages in Morus notabilis

NAC genes are important transcription factors and forms a large family in plants. They have shown to play an important role in growth and development and have also been shown to involve in regulation of stress-responsive genes. In the present study, a repertoire of NAC genes in recently published mulberry genome has been identified which consists of a total of 79 members. Structural analysis revealed that most of the NAC genes in mulberry contain two introns. The proteins encoded by them show a wide range of isoelectric points suggestive of their varied roles in varying microcellular environment. Phylogenetic and conserved motif analysis elucidate the presence of 15 sub-groups of these genes along with two novel sub-groups having distinct conserved motifs which are not present in Arabidopsis. Gene ontology term enrichment analysis and cis-element identification from their putative 1K upstream regulatory region indicates their possible role in important biological processes like organ formation, meristem establishment, senescence, and various biotic and abiotic stresses. Expression analysis across various developmental stages led to identification of their preferential expression in diverse tissues. Taken together, this work provides a solid background information related to structure, function, expression and evolution of NAC gene family in mulberry.

Biofuel Potential of Plants Transformed Genetically with NAC Family Genes.

NAC genes contribute to enhance survivability of plants under conditions of environmental stress and in secondary growth of the plants, thereby building biomass. Thus, genetic transformation of plants using NAC genes provides a possibility to tailor biofuel plants. Over-expression studies have indicated that NAC family genes can provide tolerance to various biotic and abiotic stresses, either by physiological or biochemical changes at the cellular level, or by affecting visible morphological and anatomical changes, for example, by development of lateral roots in a number of plants. Over-expression of these genes also work as triggers for development of secondary cell walls. In our laboratory, we have observed a NAC gene from Lepidium latifolium contributing to both enhanced biomass as well as cold stress tolerance of model plants tobacco. Thus, we have reviewed all the developments of genetic engineering using NAC genes which could enhance the traits required for biofuel plants, either by enhancing the stress tolerance or by enhancing the biomass of the plants.

Comprehensive analysis of NAC transcription factors in diploid Gossypium: sequence conservation and expression analysis uncover their roles during fiber development.

Determining how function evolves following gene duplication is necessary for understanding gene expansion. Transcription factors (TFs) are a class of proteins that regulate gene expression by binding to specific cis-acting elements in the promoters of target genes, subsequently activating or repressing their transcription. In the present study, we systematically examined the functional diversification of the NAC transcription factor (NAC-TFs) family by analyzing their chromosomal location, structure, phylogeny, and expression pattern in Gossypium raimondii (Gr) and G. arboreum (Ga). The 145 and 141 NAC genes identified in the Gr and Ga genomes, respectively, were annotated and divided into 18 subfamilies, which showed distinct divergence in gene structure and expression patterns during fiber development. In addition, when the functional parameters were examined, clear divergence was observed within tandem clusters, which suggested that subfunctionalization had occurred among duplicate genes. The expression patterns of homologous gene pairs also changed, suggestive of the diversification of gene function during the evolution of diploid cotton. These findings provide insights into the mechanisms underlying the functional differentiation of duplicated NAC-TFs genes in two diploid cotton species.

Overexpression of a Stress-Responsive NAC Transcription Factor Gene ONAC022 Improves Drought and Salt Tolerance in Rice.

The NAC transcription factors play critical roles in regulating stress responses in plants. However, the functions for many of the NAC family members in rice are yet to be identified. In the present study, a novel stress-responsive rice NAC gene, ONAC022, was identified. Expression of ONAC022 was induced by drought, high salinity, and abscisic acid (ABA). The ONAC022 protein was found to bind specifically to a canonical NAC recognition cis-element sequence and showed transactivation activity at its C-terminus in yeast. The ONAC022 protein was localized to nucleus when transiently expressed in Nicotiana benthamiana. Three independent transgenic rice lines with overexpression of ONAC022 were generated and used to explore the function of ONAC022 in drought and salt stress tolerance. Under drought stress condition in greenhouse, soil-grown ONAC022-overexpressing (N22oe) transgenic rice plants showed an increased drought tolerance, leading to higher survival ratios and better growth than wild-type (WT) plants. When grown hydroponically in Hogland solution supplemented with 150 mM NaCl, the N22oe plants displayed an enhanced salt tolerance and accumulated less Na+ in roots and shoots as compared to WT plants. Under drought stress condition, the N22oe plants exhibited decreased rates of water loss and transpiration, reduced percentage of open stomata and increased contents of proline and soluble sugars. However, the N22oe lines showed increased sensitivity to exogenous ABA at seed germination and seedling growth stages but contained higher level of endogenous ABA. Expression of some ABA biosynthetic genes (OsNCEDs and OsPSY), signaling and regulatory genes (OsPP2C02, OsPP2C49, OsPP2C68, OsbZIP23, OsAP37, OsDREB2a, and OsMYB2), and late stress-responsive genes (OsRAB21, OsLEA3, and OsP5CS1) was upregulated in N22oe plants. Our data demonstrate that ONAC022 functions as a stress-responsive NAC with transcriptional activator activity and plays a positive role in drought and salt stress tolerance through modulating an ABA-mediated pathway.

Identification, Expression and Variation Analysis of Salt Tolerance Related GmNAC Genes in Soybean

NAC genes play an important role in plant stress tolerance. In this study, bioinformatic method was used to identify the stress related GmNAC gene in soybean. The expression of candidated GmNAC genes in root and leaf was analyzed in soybean with NaCl treatment by Real-time PCR. Reverse transcription PCR was performed to clone genes with significant difference in expression. The results showed that there were 175 genes in soybean GmNAC gene family. There were 11 GmNAC proteins with highly conserved NAC located on the same evolutionary branch with the stress related NAC proteins in rice and Arabidopsis. The expression of 11 GmNAC genes in soybean root was higher than that in leaf. The GmNAC genes were all induced by NaCl stress, but part of the GmNAC genes showed different expression levels between root and leaf in soybean varieties with different salt tolerances. There were three synonymous mutations and one non-synonymous mutation on the CDS region of Glyma06g11970.1 and one synonymous mutation on the CDS region of Glyma06g16440.2 in Qihuang 34, Xudou 10, and Fendou 95.

Transcriptomic analysis suggests a key role for SQUAMOSA PROMOTER BINDING PROTEIN LIKE, NAC and YUCCA genes in the heteroblastic development of the temperate rainforest tree Gevuina avellana (Proteaceae).

Heteroblasty, the temporal development of the meristem, can produce diverse leaf shapes within a plant. Gevuina avellana, a tree from the South American temperate rainforest shows strong heteroblasty affecting leaf shape, transitioning from juvenile simple leaves to highly pinnate adult leaves. Light availability within the forest canopy also modulates its leaf size and complexity. Here we studied how the interaction between the light environment and the heteroblastic progression of leaves is coordinated in this species. We used RNA-seq on the Illumina platform to compare the range of transcriptional responses in leaf primordia of G.avellana at different heteroblastic stages and growing under different light environments. We found a steady up-regulation of SQUAMOSA PROMOTER BINDING PROTEIN LIKE (SPL), NAC, YUCCA and AGAMOUS-LIKE genes associated with increases in age, leaf complexity, and light availability. In contrast, expression of TCP, TPR and KNOTTED1 homeobox genes showed a sustained down-regulation. Additionally, genes involved in auxin synthesis/transport and jasmonate activity were differentially expressed, indicating an active regulation of processes controlled by these hormones. Our large-scale transcriptional analysis of the leaf primordia of G.avellana sheds light on the integration of internal and external cues during heteroblastic development in this species.

ZmCIPK8, a CBL-interacting protein kinase, regulates maize response to drought stress

Plant CBL-interacting protein kinases (CIPKs) play an important role in stress signaling transduction and enhancing plant stress tolerance. However, the functions of most CIPKs in crop plants such as maize have not been studied. Here, a novel CIPK gene, ZmCIPK8, was cloned and characterized from maize (Zea mays). The ZmCIPK8 gene has 14 introns and its encoded protein shares high homology to Arabidopsis and rice CIPKs. Yeast two-hybrid and bimolecular fluorescence complementation assay demonstrated that ZmCIPK8 interacted with ZmCBL1, ZmCBL4 and ZmCBL9. Quantitative RT-PCR analysis revealed that the mRNA accumulation of ZmCIPK8 in maize leaves and roots was promoted by drought stress. GUS gene expression driven by the ZmCIPK8 promoter was in an organ-dependent pattern and induced in Arabidopsis seedlings under drought stress. Over-expression of ZmCIPK8 in tobacco induced the expression of the NAC, CBF, and Rd29A genes and enhanced drought tolerance of transgenic tobacco seedlings. Thus, ZmCIPK8 perhaps is involved in plant response to drought and other abiotic stress through regulating stress-related genes.

NAC transcription factors in plant multiple abiotic stress responses: progress and prospects.

Abiotic stresses adversely affect plant growth and agricultural productivity. According to the current climate prediction models, crop plants will face a greater number of environmental stresses, which are likely to occur simultaneously in the future. So it is very urgent to breed broad-spectrum tolerant crops in order to meet an increasing demand for food productivity due to global population increase. As one of the largest families of transcription factors (TFs) in plants, NAC TFs play vital roles in regulating plant growth and development processes including abiotic stress responses. Lots of studies indicated that many stress-responsive NAC TFs had been used to improve stress tolerance in crop plants by genetic engineering. In this review, the recent progress in NAC TFs was summarized, and the potential utilization of NAC TFs in breeding abiotic stress tolerant transgenic crops was also be discussed. In view of the complexity of field conditions and the specificity in multiple stress responses, we suggest that the NAC TFs commonly induced by multiple stresses should be promising candidates to produce plants with enhanced multiple stress tolerance. Furthermore, the field evaluation of transgenic crops harboring NAC genes, as well as the suitable promoters for minimizing the negative effects caused by over-expressing some NAC genes, should be considered.

The NAC transcription factor family in maritime pine (Pinus Pinaster): molecular regulation of two genes involved in stress responses.

BackgroundNAC transcription factors comprise a large plant-specific gene family involved in the regulation of diverse biological processes. Despite the growing number of studies on NAC transcription factors in various species, little information is available about this family in conifers. The goal of this study was to identify the NAC transcription family in maritime pine (Pinus pinaster), to characterize ATAF-like genes in response to various stresses and to study their molecular regulation.MethodsWe have isolated two maritime pine NAC genes and using a transient expression assay in N. benthamiana leaves estudied the promoter jasmonate response.ResultsIn this study, we identified 37 NAC genes from maritime pine and classified them into six main subfamilies. The largest group includes 12 sequences corresponding to stress-related genes. Two of these NAC genes, PpNAC2 and PpNAC3, were isolated and their expression profiles were examined at various developmental stages and in response to various types of stress. The expression of both genes was strongly induced by methyl jasmonate (MeJA), mechanical wounding, and high salinity. The promoter regions of these genes were shown to contain cis-elements involved in the stress response and plant hormonal regulation, including E-boxes, which are commonly found in the promoters of genes that respond to jasmonate, and binding sites for bHLH proteins. Using a transient expression assay in N. benthamiana leaves, we found that the promoter of PpNAC3 was rapidly induced upon MeJA treatment, while this response disappeared in plants in which the transcription factor NbbHLH2 was silenced.ConclusionOur results suggest that PpNAC2 and PpNAC3 encode stress-responsive NAC transcription factors involved in the jasmonate response in pine. Furthermore, these data also suggest that the jasmonate signaling pathway is conserved between angiosperms and gymnosperms. These findings may be useful for engineering stress tolerance in pine via biotechnological approaches.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0640-0) contains supplementary material, which is available to authorized users.

A chickpea stress-responsive NAC transcription factor, CarNAC5, confers enhanced tolerance to drought stress in transgenic Arabidopsis

Environmental stresses such as drought, salinity, and cold are major factors that significantly limit agricultural productivity. NAC is a plant-specific transcription factor family, which plays essential roles in response to various abiotic stresses. We have identified a novel NAC gene CarNAC5 from chickpea in a previous study, which was induced by drought stress. In the present study, the promoter region of CarNAC5 was isolated. In silico analysis indicated that many basic cis-acting elements, which respond to environmental stresses and plant hormones, were harbored in CarNAC5 promoter region. EMSA and Yeast hybrid assays revealed that CarNAC5 could bind to the core DNA sequence CGT[G/A]. Overexpression of CarNAC5 enhanced drought tolerance in transgenic Arabidopsis plants, which was simultaneously demonstrated by the enhanced expression of abiotic stress-responsive genes and changes of several physiological indices. Our results indicated that CarNAC5 has potential for utilization in transgenic breeding to improve abiotic stress tolerances in crops.