Abscisic Acid Stress Research Articles

Characterization and Functional Analysis of ZmSWEET15a in Maize.

The sugars will eventually be exported transporters (SWEETs) gene family is a new type of sugar transporters, which plays an important role in plant growth and development, physiological metabolism, and abiotic stress. In this study, we used quantitative real-time PCR to analyze the expression of ZmSWEET15a gene in different organs of maize and under different abiotic stresses. The results showed that ZmSWEET15a was expressed in roots, stems, leaves, and grains, with the highest expression level in leaves, which was highly correlated with leaf development. Under the treatment of polyethylene glycol (PEG), NaCl, H2O2, and abscisic acid stress, the expression of ZmSWEET15a was upregulated, while under the treatment of cold stress, the expression of ZmSWEET15a was inhibited. In sugar-specific experiments, we found that sucrose was the most effective carbon source for maize seed germination. The expression analysis of ZmSWEET15a in different carbon sources suggested that the expression of ZmSWEET15a was more likely to be induced by sucrose. Overexpression of ZmSWEET15a in maize plants could reduce the sucrose content in leaves and increase the sucrose content in grains. The heterologous expression of ZmSWEET15a in the yeast mutant strain SUSY7/ura indicated that ZmSWEET15a is a sucrose transporter and pH independent. This study provides new insight into sugar transport and carbohydrate partitioning in maize and other crops, and provide more genetic information for improving crop quality at the molecular level.

Abscisic acid facilitates phosphate acquisition through the transcription factor ABA INSENSITIVE5 in Arabidopsis

Low phosphate (LP) in soil is a common nutrient stress that severely restricts agricultural production, but the role, if any, of the major stress phytohormone abscisic acid (ABA) in plant phosphate (Pi) starvation responses remains elusive. Here, we report that LP-induced ABA accumulation promotes Pi uptake in an ABA INSENSITIVE5 (ABI5)-dependent manner in Arabidopsis thaliana. LP significantly activated plant ABA biosynthesis, metabolism, and stress responses, suggesting a role of ABA in the plant response to Pi availability. LP-induced ABA accumulation and expression of two major high-affinity phosphate transporter genes PHOSPHATE TRANSPORTER1;1/1;4 (PHT1;1/1;4) were severely impaired in a mutant lacking BETA-GLUCOSIDASE1 (BG1), which converts conjugated ABA to active ABA, and the mutant had shorter roots and less Pi content than wild-type plants under LP conditions. Moreover, a mutant of ABI5, which encodes a central transcription factor in ABA signaling, also exhibited suppressed root elongation and had reduced Pi content under LP conditions. ABI5 facilitated Pi acquisition by activating the expression of PHT1;1 by directly binding to its promoter, while overexpression of PHT1;1 completely rescued its Pi content under LP conditions. Together, our findings illustrate a molecular mechanism by which ABA positively modulates phosphate acquisition through ABI5 in the Arabidopsis response to phosphate deficiency.

Ethylene Suppresses Abscisic Acid, Modulates Antioxidant System to Counteract Arsenic-Inhibited Photosynthetic Performance in the Presence of Selenium in Mustard

Arsenic (As) stress provokes various toxic effects in plants that disturbs its photosynthetic potential and hampers growth. Ethylene and selenium (Se) have shown regulatory interaction in plants for metal tolerance; however, their synergism in As tolerance through modification of the antioxidant enzymes and hormone biosynthesis needs further elaboration. With this in view, we investigated the impact of ethylene and Se in the protection of photosynthetic performance against As stress in mustard (Brassica juncea L.). Supplementation with ethephon (2-chloroethylphosphonic acid; ethylene source) and/or Se allayed the negative impact of As-induced toxicity by limiting As content in leaves, enhancing the antioxidant defense system, and decreasing the accumulation of abscisic acid (ABA). Ethylene plus Se more prominently regulated stomatal behavior, improved photosynthetic capacity, and mitigated As-induced effects. Ethephon in the presence of Se decreased stress ethylene formation and ABA accumulation under As stress, resulting in improved photosynthesis and growth through enhanced reduced glutathione (GSH) synthesis, which in turn reduced the oxidative stress. In both As-stressed and non-stressed plants treated with ethylene action inhibitor, norbornadiene, resulted in increased ABA and oxidative stress with reduced photosynthetic activity by downregulating expression of ascorbate peroxidase and glutathione reductase, suggesting the involvement of ethylene in the reversal of As-induced toxicity. These findings suggest that ethephon and Se induce regulatory interaction between ethylene, ABA accumulation, and GSH metabolism through regulating the activity and expression of antioxidant enzymes. Thus, in an economically important crop (mustard), the severity of As stress could be reduced through the supplementation of both ethylene and Se that coordinate for maximum stress alleviation.

OsABT, a Rice WD40 Domain-Containing Protein, Is Involved in Abiotic Stress Tolerance

Plant growth and crop productivity are severely affected by abiotic stress on a global scale. WD40 repeat-containing proteins play a significant role in the development and environmental adaptation of eukaryotes. In this study, OsABT, a stress response gene, was cloned from rice (Oryza sativa L. cv. Nipponbare). OsABT encodes a protein containing seven WD40 domains. Expression analysis revealed that the OsABT gene was first up-regulated and then down-regulated following treatment with abscisic acid (ABA) and NaCl, but was down-regulated when treated with PEG8000. Subcellular localization results showed that OsABT was located in the cytoplasm and nucleus of Arabidopsis roots. OsABT transgenic Arabidopsis showed significantly increased tolerance to ABA and salt stress during plant seedling development. However, the transgenic lines were more sensitive to drought stress. Moreover, OsABT can interact with OsABI2, a component of ABA signaling pathway. These results showed that OsABT plays a positive regulatory role in response to salt stress and a negative role in response to drought stress in Arabidopsis.

Coordination of plant growth and abiotic stress responses by tryptophan synthase β subunit 1 through modulation of tryptophan and ABA homeostasis in Arabidopsis

To adapt to changing environments, plants have evolved elaborate regulatory mechanisms balancing their growth with stress responses. It is currently unclear whether and how the tryptophan (Trp), the growth-related hormone auxin, and the stress hormone abscisic acid (ABA) are coordinated in this trade-off. Here, we show that tryptophan synthase β subunit 1 (TSB1) is involved in the coordination of Trp and ABA, thereby affecting plant growth and abiotic stress responses. Plants experiencing high salinity or drought display reduced TSB1 expression, resulting in decreased Trp and auxin accumulation and thus reduced growth. In comparison with the wild type, amiR-TSB1 lines and TSB1 mutants exhibited repressed growth under non-stress conditions but had enhanced ABA accumulation and stress tolerance when subjected to salt or drought stress. Furthermore, we found that TSB1 interacts with and inhibits β-glucosidase 1 (BG1), which hydrolyses glucose-conjugated ABA into active ABA. Mutation of BG1 in the amiR-TSB1 lines compromised their increased ABA accumulation and enhanced stress tolerance. Moreover, stress-induced H2O2 disrupted the interaction between TSB1 and BG1 by sulfenylating cysteine-308 of TSB1, relieving the TSB1-mediated inhibition of BG1 activity. Taken together, we revealed that TSB1 serves as a key coordinator of plant growth and stress responses by balancing Trp and ABA homeostasis.

A novel R3H protein, OsDIP1, confers ABA-mediated adaptation to drought and salinity stress in rice

AimsDehydration responsive element-binding factors (DBFs) have recently emerged as essential components of stress tolerance mechanisms in plants. In this work, we investigated the role of OsDIP1 that operate upstream of DBFs as a regulator of drought and salinity tolerance in rice.MethodsExperiments were conducted on rice plants (Oryza sativa) and included combination of physiological (plant phenotyping) and molecular methods. The latter involved real-time PCR (RT-qPCR); yeast two-hybrid, BiFC assay, GST pull-down, CoIP and firefly luciferase (LUC)/ renilla (REN) assays.ResultsOsDIP1 expression was induced by hydrogen peroxide (H2O2), ABA (abscisic acid), drought (polyethylene glycol treatment), and salt stress. Overexpression of OsDIP1 in rice enhanced drought and salinity tolerance while knocking out OsDIP1 by CRISPR-Cas9 editing resulted in drought and salt sensitive phenotype. The activity and gene expression of antioxidant defense enzymes, superoxide dismutase (SOD), catalase (CAT), was increased in OsDIP1-overexpressed transgenic rice plants, while the content of malondialdehyde (MDA) was decreased. In contrast, the content and gene expression of SODCc2 and CatB, decreased, and the content of MDA was increased in knockout of OsDIP1 rice plants, suggesting that overexpression of OsDIP1 enhances the antioxidant capacity of rice plants. The yeast two-hybrid screening test revealed that OsDIP1 interacted with ZFP36, a key zinc finger transcription factor involved in ABA-induced antioxidant defense. Moreover, OsDIP1 could modulate some key ABA-responsive genes via interacting with ZFP36.ConclusionsIn this work, we show that DIP1 plays a central role in modulating drought and salinity stress tolerance in rice.

Regulation of StTCP15 gene expression and tuber dormancy characteristics of potato by gibberellic acid, abscisic acid, and low temperature

Potato (Solanum tuberosum L.) cv. Eshu 10 was used to investigate the effects of exogenous gibberellic acid (GA3), abscisic acid (ABA), and low-temperature stress on changes of hormone content, expression patterns of StTCP15 gene, and tuber dormancy characteristics. Under GA3 treatment and low-temperature stress, tuber dormancy was broken in about one week sooner compared with the control group, but ABA treatment did not significantly promote the breaking of tuber dormancy. The results of hormone determination using liquid chromatography-mass spectrometry (LC-MS/MS) showed that the content of ABA in tubers treated with GA3 or low-temperature stress was lower than in the control group, and it was higher than in the control group under ABA treatment. The GA3 content of tubers was higher than in the control group under GA3 treatment and lower under low-temperature stress. During dormancy, the ABA content continued to increase and GA3 content fluctuated, ABA content rapidly decreased and GA3 content rapidly increased when the dormancy was breaking, and both ABA content and GA3 content increased during germination. The results from the assay of real-time quantitative PCR showed that the expression of the StTCP15 gene was continuously increased during the dormant period in all groups, and the expression of the StTCP15 gene was the highest at the time of dormancy release. The expression of the StTCP15 gene was increased about 15 times on the 7th d under low-temperature stress and was restored at room temperature. Thus, the StTCP15 gene can respond to GA3, ABA, and low-temperature stress and may be involved in the release of potato tuber dormancy.

How long should a kiss last between a kinase and its substrate?

In the presence of abscisic acid or environmental stress, activated SnRK2s transiently phosphorylate Raptor1B, a regulatory component of the TOR complex, to inhibit plant growth. To examine such transient interactions between a kinase and its substrate, comprehensive genetic or biochemistry evidence is more conclusive than a single negative co-immunoprecipitation test.

Effect of exogenous abscisic acid on growth, biochemical changes and antioxidant enzyme activities in black gram [Vigna mungo (L.) Hepper] under drought

Drought stress is a significant limitation to the production and yield of black gram [Vigna mungo (L.) Hepper] and abscisic acid plays a subtle role in the biosynthetic pathway during drought stress. The present study examined the morphology, biochemical, relative water content and antioxidant activities of black gram plants treated with various abscisic acid (ABA) levels under drought conditions. The ABA at 50 ppm concentration showed promising recovery of morphological characters compared to other concentrations. The photosynthetic pigments, biochemical constituents, malondialdehyde and antioxidant enzymes (CAT, POD, SOD and APX) were active at 50 ppm. Infrared Spectroscopic (IR) analysis of black gram leaves in a bandwidth ranging from 400 to 4000 cm-1 revealed a change in metabolites under drought stress and exogenous ABA application. The FTIR spectroscopy results warrant that the expression of functional organic compounds in the drought response of black gram can aid in the discovery of new drought-tolerant traits. As a result, ABA-responsive cultivars can cultivate and produce drought-resistant black gram varieties in arid and semi-arid climates.

CBF4/DREB1D represses XERICO to attenuate ABA, osmotic and drought stress responses in Arabidopsis.

Water stress can severely impact plant growth, productivity and yield. Consequently, plants have evolved various strategies through which they can respond and adapt to their environment. XERICO (XER) is a stress-responsive RING E3 ubiquitin ligase that modulates abscisic acid (ABA) levels and promotes drought tolerance when overexpressed. To better understand the biological role of XER in stress responses, we characterized a xer-1 hypomorphic mutant and a CRISPR/Cas9-induced xer-2 null mutant in Arabidopsis. Both xer mutant alleles exhibited increased drought sensitivity, supporting the results from overexpression studies. Furthermore, we discovered that both xer mutants have greater stomatal indices and that XER is expressed in epidermal cells, indicating that XER functions in the epidermis to repress stomatal development. To explore XER spatiotemporal and stress-dependent regulation, we conducted a yeast one-hybrid screen and found that CBF4/DREB1D associates with the XER 5' untranslated region (5'-UTR). We generated three cbf4 null mutants with CRISPR/Cas9 and showed that CBF4 negatively regulates ABA responses, promotes stomatal development and reduces drought tolerance, in contrast to the roles shown for XER. CBF4 is induced by ABA and osmotic stress, and localizes to the nucleus where it downregulates XER expression via the DRE element in its 5'-UTR. Lastly, genetic interaction studies confirmed that xer is epistatic to cbf4 in stomatal development and in ABA, osmotic and drought stress responses. We propose that the repression of XER by CBF4 functions to attenuate ABA signaling and stress responses to maintain a balance between plant growth and survival under adverse environmental conditions.

Arabidopsis CAMTA3/SR1 is involved in drought stress tolerance and ABA signaling

Calcium/calmodulin signals are important for various cellular and physiological activities in plants. Calmodulin binding transcription activators also named Signal Responsive (SR) proteins belong to an important calcium/calmodulin-dependent transcription factor family that plays critical roles in stress responses. However, the role of SRs in abscisic acid (ABA) regulated plant responses to drought stress is largely unknown. Here, we characterized the role of Arabidopsis SR1 in drought stress tolerance and ABA response by analyzing the phenotypes of SR1 knockout and SR1-overexpression plants. sr1 mutants which accumulate salicylic acid (SA) were found more sensitive to drought stress and showed a higher water loss rate as compared with wild-type. By contrast, SR1-overexpression lines exhibited increased drought tolerance and less water loss than wild-type. Furthermore, sr1 mutants showed reduced ABA response in seed germination, root elongation, and stomatal closure, while SR1-overexpression lines displayed more sensitive to ABA than wild-type. In addition, the drought-sensitive and ABA-insensitive phenotypes of sr1 mutants were recovered by diminishing SA accumulation via knockouts of SA synthesizer ICS1 or activator PAD4, or through expression of SA-degrading enzyme NahG. Some drought/ABA-responsive genes exhibited differentially expressed in sr1 mutants and SR1-overexpression plants. These results suggest that SR1 plays a positive role in drought stress tolerance and ABA response, and drought/ABA responses are antagonized by SA accumulation that is negatively regulated by SR1.

Identification and Analysis of the EIN3/EIL Gene Family in Populus × xiaohei T. S. Hwang et Liang: Expression Profiling during Stress

The ethylene-insensitive 3-like (EIN3/EIL) gene family, as a transcriptional activator in plants, not only plays an important role in the ethylene-signaling pathway in regulating plant growth and development but also participates in the defense against various biotic and abiotic stresses. However, there are few studies on the functions of EIN3/EIL genes in woody plants. Populus × xiaohei is a kind of tree species with strong drought resistance and salt-alkali tolerance and, thus, is an ideal subject for studying abiotic stress mechanisms in trees. Eight EIN3/EIL genes were cloned from Populus × xiaohei. Bioinformatic analysis showed that the PsnEIN3/EIL gene contained a highly conserved EIN3 domain, N-terminal sites rich in proline and glutamine, and other EIN3/EIL family structural characteristics. The results of a multi-species phylogenetic analysis showed that the family EIN3/EIL proteins were divided into three groups (A, B, and C). EIL3 and EIL4 belonged to groups A and B, while EIL2 and EIN3 generally belonged to group C. Analysis of tissue expression characteristics showed that PsnEIN3/EIL was expressed in different tissues and was involved in the development of stem nodes and leaves. The response analysis of the expression of PsnEIN3/EIL under abscisic acid (ABA) and abiotic stresses (salts, heavy metals, alkaline conditions, and drought) showed changes in expression, suggesting that PsnEIN3/EIL may be involved in the processes of plant hormone responses to salts, heavy metals, alkaline conditions, and drought. This study provides a foundation for further elucidation of the functions of EIN3/EIL genes in forest growth and development and abiotic stress responses.

Genome-Wide Identification and Analysis of bZIP Gene Family and Resistance of TaABI5 (TabZIP96) under Freezing Stress in Wheat (Triticum aestivum).

The basic leucine zipper (bZIP) regulates plant growth and responds to stress as a key transcription factor of the Abscisic acid (ABA) signaling pathway. In this study, TabZIP genes were identified in wheat and the gene structure, physicochemical properties, cis-acting elements, and gene collinearity were analyzed. RNA-Seq and qRT-PCR analysis showed that ABA and abiotic stress induced most TabZIP genes expression. The ectopic expression of TaABI5 up-regulated the expression of several cold-responsive genes in Arabidopsis. Physiological indexes of seedlings of different lines under freezing stress showed that TaABI5 enhanced the freezing tolerance of plants. Subcellular localization showed that TaABI5 is localized in the nucleus. Furthermore, TaABI5 physically interacted with cold-resistant transcription factor TaICE1 in yeast two-hybrid system. In conclusion, this study identified and analyzed members of the TabZIP gene family in wheat. It proved for the first time that the gene TaABI5 affected the cold tolerance of transgenic plants and was convenient for us to understand the cold resistance molecular mechanism of TaABI5. These results will provide a new inspiration for further study on improving plant abiotic stress resistance.

Time-Resolved Analysis of Candidate Gene Expression and Ambient Temperature During Bud Dormancy in Apple.

Winter dormancy – a period of low metabolic activity and no visible growth – appears as an adaptation to harsh winter conditions and can be divided into different phases. It is tightly controlled by environmental cues, with ambient temperature playing a major role. During endodormancy, a cultivar-specific amount of cold needs to be perceived, and during ecodormancy, heat hours accumulate before bud burst and anthesis in spring. Expression analysis, performed in several key fruit tree species, proved to be very useful in elucidating the molecular control of onset and release of dormancy. However, the time resolution of these experiments has been limited. Therefore, in this study, dense time-series expression analysis was conducted for 40 candidate genes involved in dormancy control, under the cool-temperate climate conditions in Dresden. Samples were taken from the cultivars ‘Pinova’ and ‘Gala,’ which differ in flowering time. The set of candidate genes included well-established dormancy genes such as DAM genes, MdFLC-like, MdICE1, MdPRE 1, and MdPIF4. Furthermore, we tested genes from dormancy-associated pathways including the brassinosteroid, gibberellic acid, abscisic acid (ABA), cytokinin response, and respiratory stress pathways. The expression patterns of well-established dormancy genes were confirmed and could be associated with specific dormancy phases. In addition, less well-known transcription factors and genes of the ABA signaling pathway showed associations with dormancy progression. The three ABA signaling genes HAB1_chr15, HAI3, and ABF2 showed a local minimum of gene expression in proximity of the endodormancy to ecodormancy transition. The number of sampling points allowed us to correlate expression values with temperature data, which revealed significant correlations of ambient temperature with the expression of the Malus domestica genes MdICE1, MdPIF4, MdFLC-like, HAB1chr15, and the type-B cytokinin response regulator BRR9. Interestingly, the slope of the linear correlation of temperature with the expression of MdPIF4 differed between cultivars. Whether the strength of inducibility of MdPIF4 expression by low temperature differs between the ‘Pinova’ and ‘Gala’ alleles needs to be tested further.

Overexpression of an ABA-inducible homeodomain-leucine zipper I gene MsHB7 confers salt stress sensitivity to alfalfa

Alfalfa (Medicago sativa L.) is the foremost forage legume crop worldwide for diary production and ecological balance. Salinity has become a crucial factor affecting crop productivity. Plant unique homeodomain-leucine zipper (HD-Zip) transcription factors are reported to play significant roles in abiotic stress signaling transduction and regulation. This study was conducted to elucidate the regulatory roles of an alfalfa HD-Zip I transcription factor, Medicago sativa homeobox 7 (MsHB7), on salt stress response. MsHB7 was indicated to be located in nucleus with transactivation activity. Expression pattern analysis revealed that MsHB7 was induced by abscisic acid (ABA) and salt (NaCl) stress. Enhanced salt sensitivity in MsHB7-overexpressing alfalfa was reflected by the morphological and physiological performances. In addition, genes regarding antioxidation (MspxdC and MsCatalase4) and ABA response (MsABI1 and MsSnRK2.6) were down-regulated in MsHB7-overexpressing alfalfa compared with wild type. These data suggested that MsHB7 played a negative role on alfalfa salt stress regulation, which could be through repressing expressions of ABA-responsive genes, MsABI1 and MsSnRK2.6, and antioxidant enzyme coding genes, MspxdC and MsCatalase4. This study could enlarge knowledge of alfalfa HD-Zip I gene regulation mechanism, and provide important strategy for salt-tolerant alfalfa breeding.

Affinity Purification Followed by Liquid Chromatography-Tandem Mass Spectrometry to Identify Proteins Interacting with ABA Signaling Components.

Abscisic acid (ABA) is a key phytohormone involved in plant development, seed germination and responses to osmotic stresses, such as drought and high salinity. SNF1-related protein kinases (SnRK2s) play important roles in ABA-dependent and ABA-independent osmotic stress signaling. SnRK2s phosphorylate transcription factors and ion channels in response to ABA or osmotic stress to induce the expression of stress-responsive genes and stomatal closure, respectively, to confer osmotic stress tolerance. The activity of SnRK2s is directly or indirectly regulated by several protein factors. Identification of downstream substrates or upstream regulators of SnRK2s is very useful for elucidating protein components that regulate ABA and osmotic stress signaling. Here, we describe the use of affinity purification by coimmunoprecipitation and liquid chromatography-tandem mass spectrometry to identify protein complexes involved in ABA and osmotic stress signaling in plants. We previously identified several protein factors that regulate ABA and osmotic stress signaling by using this method.

Silencing of SlMYB55 affects plant flowering and enhances tolerance to drought and salt stress in tomato

The transcription factors of the MYB family are involved in plant growth and development and responses to biotic and abiotic stresses. Here, we isolated the R2R3-MYB transcription factor gene SlMYB55 and found that it is responsive to abscisic acid (ABA), drought, and salt stress. Notably, the expression levels of multiple stress-related and inflorescence and flowering time-related genes were changed in SlMYB55-RNAi plants compared to wild-type plants. Transient tobacco expression experiments indicated that SlMYB55 directly targets the WUS and 4CL genes to regulate the development of inflorescence and flavonoid biosynthesis. Yeast two-hybrid experiments showed that the SlMYB55 protein interacts with the MADS-box family protein MBP21. Based on these results, we concluded that SlMYB55 affects the biosynthesis of ABA, regulates drought and salt responses through ABA-mediated signal transduction pathways, and directly or indirectly affects the expression of genes related to drought and salt response, flowering time, sepal size and inflorescence, thereby regulating stress tolerance and flower development. In summary, this study identified essential roles for SlMYB55 in regulating drought and salt tolerance and flower development.

Genome-Wide Identification and Comparative Analysis of the ASR Gene Family in the Rosaceae and Expression Analysis of PbrASRs During Fruit Development.

The members of the Abscisic Acid (ABA) Stress and Ripening gene family (ASR) encode a class of plant-specific proteins with ABA/WDS domains that play important roles in fruit ripening, abiotic stress tolerance and biotic stress resistance in plants. The ASR gene family has been widely investigated in the monocotyledons and dicotyledons. Although the genome sequence is already available for eight fruit species of the Rosaceae, there is far less information about the evolutionary characteristics and the function of the ASR genes in the Rosaceae than in other plant families. Twenty-seven ASR genes were identified from species in the Rosaceae and divided into four subfamilies (I, II, III, and IV) on the basis of structural characteristics and phylogenetic analysis. Purifying selection was the primary force for ASR family gene evolution in eight Rosaceae species. qPCR experiments showed that the expression pattern of PbrASR genes from Pyrus bretschneideri was organ-specific, being mainly expressed in flower, fruit, leaf, and root. During fruit development, the mRNA abundance levels of different PbrASR genes were either down- or up-regulated, and were also induced by exogenous ABA. Furthermore, subcellular localization results showed that PbrASR proteins were mainly located in the nucleus and cytoplasm. These results provide a theoretical foundation for investigation of the evolution, expression, and functions of the ASR gene family in commercial fruit species of the Rosaceae family.

Genome-Wide Identification, Characterization and Expression Analysis of the CIPK Gene Family in Potato (Solanum tuberosum L.) and the Role of StCIPK10 in Response to Drought and Osmotic Stress.

The potato (Solanum tuberosum L.), one of the most important food crops worldwide, is sensitive to environmental stresses. Sensor–responder complexes comprising calcineurin B-like (CBL) proteins and CBL-interacting protein kinases (CIPKs) not only modulate plant growth and development but also mediate numerous stress responses. Here, using a Hidden Markov Model and BLAST searches, 27 CIPK genes were identified in potato and divided into five groups by phylogenetic analysis and into two clades (intron-poor and intron-rich) by gene structure analysis. Quantitative reverse-transcription PCR (qRT-PCR) assays revealed that StCIPK genes play important roles in plant growth, development and abiotic stress tolerance. Up-regulated expression of StCIPK10 was significantly induced by drought, PEG6000 and ABA. StCIPK10 enhances both the ability of potato to scavenge reactive oxygen species and the content of corresponding osmoregulation substances, thereby strengthening tolerance to drought and osmotic stress. StCIPK10 is located at the intersection between the abscisic acid and abiotic stress signaling pathways, which control both root growth and stomatal closure in potato. In addition, StCIPK10 interacts with StCBL1, StCBL4, StCBL6, StCBL7, StCBL8, StCBL11 and StCBL12, and is specifically recruited to the plasma membrane by StCBL11.

OsVDE, a xanthophyll cycle key enzyme, mediates abscisic acid biosynthesis and negatively regulates salinity tolerance in rice.

OsVDE, a lipocalin-like protein in chloroplasts, negatively regulated the ABA biosynthesis and stomatal closure under salt stress in rice seedlings. Violaxanthin de-epoxidase (VDE) is a key enzyme of xanthophyll cycle. It plays a critical role in abscisic acid (ABA) biosynthesis, growth and stress responses in plants. Although functions of several VDE genes have been characterized, it is largely unknown whether OsVDE regulates the ABA biosynthesis and salt stress tolerance in rice. In this study, we generated the OsVDE overexpressing and CRISPR-Cas9-mediated gene-editing transgenic lines, and identified that the gene-editing mutant lines showed the dwarfism, shorter panicle and lower seed-setting rate than the wild type whereas the overexpression lines did not exhibit the difference from the wild type. In addition, the gene-editing transgenic lines were hypersensitive to exogenous ABA during germination. Under salt stress, the gene-editing transgenic seedlings had a higher ABA level, higher stomatal closure percentage and higher survival rate than the wild type. The qRT-PCR analysis confirmed that OsVDE negatively regulated the OsNECD2/4/5 expressions, ABA biosynthesis and salt stress tolerance in rice seedlings. These results provide new evidence that VDE plays an essential role in ABA biosynthesis and salt stress tolerance in plants.