Abscisic Acid Research Articles

Roles of Ethylene and Abscisic Acid Produced by Alternaria alternata and Fusarium fujikuroi in Postharvest Disease of Blueberries.

Blueberries are susceptible to postharvest fungal decay. This study identified Alternaria alternata and Fusarium fujikuroi isolated from infected blueberries using morphological, molecular, and phylogenetic analyses. Both fungi simultaneously produced abscisic acid (ABA) and ethylene, with ethylene levels in infected fruit reaching 35-53-fold higher than in healthy fruit. High ABA and ethylene accumulation at infection sites promoted lesion expansion. Exogenous β-carotene did not affect fungal growth but significantly upregulated fungal ABA synthesis, indicating dual ABA biosynthesis pathways (microbial- and plant-derived). Infected cells exhibited 270-525-fold higher ABA levels than controls, driven by fungal utilization of host β-carotene. Exogenous β-carotene and ABA accelerated lesion expansion by suppressing host resistance. Conversely, deferoxamine mesylate reduced lesion areas and hormone levels, enhancing disease resistance. These findings demonstrated that the production of ABA and ethylene by A. alternata and F. fujikuroi might be involved in the pathogenic mechanism of blueberry rot.

Stomatal CO2 Sensing in Plants: Control of Gas Exchange and Interactions with Environmental Stimuli.

Stomatal pores in land plants rapidly and reversibly open and close in response to diurnal changes in leaf carbon dioxide (CO2) concentration. Studies have suggested that CO2 is sensed by guard cells with relevant amplifying contributions from mesophyll tissue. CO2 concentration changes trigger rapid signal transduction events involving protein phosphorylation in guard cells. Moreover, molecular crosstalk and physiological interactions of the stomatal CO2 response with other environmental conditions and stimuli, including light, temperature, drought and abscisic acid, are reviewed here. Genetic studies have revealed several key genes and provided important insights into the stomatal CO2 sensors and signal transduction mechanisms. The primary CO2/HCO3- sensor in Arabidopsis guard cells was recently identified. QTL analyses have shown that early guard cell CO2 signal transduction components regulate water use efficiency (WUE). In this review, we describe the molecular details of stomatal CO2 sensing by CO2/HCO3--induced interaction of two protein kinases, the HT1 Raf-like kinase and the MPK4/MPK12 MAP kinases. The evolutionary emergence of, physiological relevance of, and potential for improvement of WUE of plants via the stomatal CO2 response and open questions in this research field are discussed.

CRISPR/Cas9-Mediated Knockout of OsbZIP76 Reveals Its Role in ABA-Associated Immune Signaling in Rice

The basic leucine zipper (bZIP) transcription factors are involved in a wide range of physiological processes in plants, including hormone signaling, stress responses, and growth and development regulation. They play a key role in abscisic acid (ABA)-mediated immune regulation. However, the immune-related function of OsbZIP76 in rice remains poorly understood. In this study, we generated OsbZIP76 knockout (KO) lines using CRISPR/Cas9-mediated genome editing and examined their phenotypic responses to the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo) and the fungal pathogen Magnaporthe oryzae. The KO lines showed increased susceptibility to both pathogens compared to wild-type (WT) plants. Furthermore, qRT-PCR analysis revealed that, upon pathogen infection, the expression of pathogenesis-related genes such as PR1a, PR5, and NPR1 was significantly suppressed in the KO lines. ABA treatment experiments showed that KO lines were hypersensitive to exogenous ABA, indicating a role for OsbZIP76 in ABA perception and signaling. Notably, the expression of the OsbZIP76 gene itself was strongly induced by both ABA treatment and pathogen infection, supporting its role as a positive regulator in ABA-associated immune signaling. Overall, this study demonstrates that OsbZIP76 functions as an important immune regulator by integrating defense gene expression with ABA signaling, providing new insights into the molecular crosstalk between hormonal signaling and pathogen defense mechanisms.

Genomic and Functional Insights Into Bacillus cereus SH-10 for Mitigating Lead Stress in Soybean.

Beneficial microbes serve as powerful biological tools for enhancing stress tolerance in crops. This study aimed to isolate stress-tolerant, plant growth-promoting bacterium, characterise it using high-throughput next-generation sequencing and expression profiling and assess its potential in improving soybean (Glycine max (L.) Merr.) growth and development under lead (Pb) stress. We identified Bacillus cereus SH-10 as a metal-resistant rhizobacterium capable of tolerating Pb concentrations exceeding 75 mg/kg. When inoculated into soybean plants under Pb stress, SH-10 significantly improved phosphorus and calcium uptake and reduced Pb accumulation. This reduction was associated with increased expression of the stress signalling protein GmCYP82A3. SH-10 also modulated the phytohormone balance by lowering abscisic acid (ABA) levels in shoots and enhancing salicylic acid (SA) biosynthesis. These hormonal shifts corresponded with the downregulation of ABA biosynthesis-related genes (GmNCED1, NCED3, GmbZIP) and the upregulation of the SA biosynthesis gene GmPAL1. Furthermore, SH-10 significantly mitigated oxidative stress in Pb-exposed plants, while enhancing antioxidant activities. The study also identified two phytohormone biosynthesis pathways in rhizobacteria: (1) Terpenes → β-carotene → Xanthoxin → ABA, and (2) Terpenes → Geranylgeranyl diphosphate → gibberellic acid. These findings highlight Bacillus cereus SH-10 as a promising biofertiliser that alleviates Pb toxicity in crops.

ETHYLENE INSENSITIVE2-like protein mediates submergence and drought responses in Physcomitrium patens.

ETHYLENE INSENSITIVE 2 (EIN2) is an Nramp family transmembrane protein recognized as an essential component of ethylene signaling in angiosperms. However, its functions in other plant systems are not fully understood. Here, we demonstrate that ppein2ab mutants of the moss Physcomitrium patens, in which both EIN2-like genes have been disrupted, do not show a typical ethylene-mediated escape response following submergence. Interestingly, ppein2ab mutants showed reduced sensitivity to abscisic acid (ABA), a phytohormone that mediates drought stress responses. The ppein2ab plants were sensitive to hyperosmosis and freezing stress and exhibited reduced late embryogenesis abundant protein accumulation. Furthermore, ppein2ab mutants showed reduced activation of both SNF1-related protein kinase2 (SnRK2), the central activator of ABA and osmostress signaling, and the B3-RAF kinase ARK/PpCTR1L, a positive regulator of SnRK2. These results indicate that EIN2 is a dual function signaling component mediating both submergence and drought signaling in bryophytes. The diminished ABA responses in ppein2ab were restored by introduction of Arabidopsis EIN2 and the EIN2 orthologs of the Charophyceaen alga Chara braunii, suggesting functional conservation of EIN2 orthologs in Phragmoplastophyta.

A Novel Phospholipase A1 Gene from Tritipyrum Improves Wheat Early Ripening and Salt Tolerance.

It is important to breed salt-tolerant and early ripening wheat cultivars. Using preliminary transcriptomic data, a phospholipase A1 gene, TtPLA1-1, was screened from salt-tolerant Tritipyrum "Y1805". The TtPLA1-1 expression level in roots was significantly higher than those in stems and leaves under salt stress. TtPLA1-1 overexpression (OE) wheat lines showed strong salt tolerance levels and early ripening. The PLA, lysophospholipid, free fatty acid, proline, and soluble sugar contents, as well as root vitality and catalase and peroxidase activities, in OE lines were significantly higher than those in the WT plants under normal and salt-stress conditions. However, the malondialdehyde content decreased. Conversely, TtPLA1-1 downregulation in "Y1805" using a virus-induced gene silencing system decreased the salt tolerance. According to both transcriptome and yeast two-hybrid analyses, the salt stress-, plant growth-, and flowering-related terms "response to water deprivation", "response to abscisic acid", "removal of superoxide radicals", "carbohydrate metabolic process", "intracellular signal transduction", "l-asparagine biosynthetic process", "positive regulation of growth", and "regulation of photoperiodism, flowering" were enriched. An interaction between TtPLA1-1 and TtRFI2L (RED AND FAR-RED INSENSITIVE 2-like) was revealed. Additionally, TtRFI2L silencing reduced the salt tolerance. In summary, TtPLA1-1 improved wheat salt tolerance and promoted early maturation, making it a valuable gene for wheat breeding and cultivation.

Cloning and function analysis of ZmICE1a, a contributor to the melioration of maize kernel traits

ABSTRACT Kernel traits are important factors in determining maize yield. Gene mining and clarification of relevant gene functions associated with kernel traits is beneficial for breeding high-yield maize varieties. In our previous research, a critical quantitative trait locus (QTL), qKWEI3.1, associated with kernel weight was mapped using a maize F2:3 population derived from the parental lines SCML0849 and ZNC442. In the present study, qKWEI3.1 was fine-mapped, the ZmICE1a gene was cloned, and the relevant functions of ZmICE1a were dissected. The results showed that plants overexpressing ZmICE1a exhibited a shorter reproductive period, increased plant height, greater stem diameter, higher photosynthetic efficiency, and meliorated kernel traits. Transcriptome analysis revealed that ZmICE1a overexpression mediated differentially expressed genes (DEGs) such as SNRK2–10, the E3 ubiquitin-protein ligase AIP2, Pho1, and Pho2. Gene ontology and KEGG pathway enrichment analyses revealed that the DEGs were involved in the abscisic acid signaling pathway, starch, and sucrose metabolism. These results suggest that ZmICE1a is a critical, positive regulator promoting plant growth and meliorating kernel traits. The findings of this study have important implications for the improvement of grain yield through the application of genetic engineering in maize breeding.

Physiological and biochemical responses of pepper (Capsicum annuum) to cadmium stress: The mitigating effects of exogenous abscisic acid.

Physiological and biochemical responses of pepper (Capsicum annuum) to cadmium stress: The mitigating effects of exogenous abscisic acid.

Strigolactone (GR24) regulates fruit ripening in yft3 tomatoes by altering ABA biosynthesis.

Strigolactone (GR24) regulates fruit ripening in yft3 tomatoes by altering ABA biosynthesis.

Star of biochemical traits of heat-tolerant and heat-sensitive Phaseolus genotypes in coping with heat stress

Abstract Heat stress due to climate change irreparably affects all physiological and biochemical processes of plants, such as photosynthesis, respiration, and hormonal metabolism, decreasing growth and development and reducing yield and quality traits. It is, therefore, imperative to be acquainted with stress-related physiological responses of plants to cope with heat stress, which is predicted to continue to increase due to climate change. The goals of this study were to compare abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) contents and chlorophyll content (SPAD) and maximum quantum efficiency of PSII (F v /F m) values in Phaseolus species under heat-stress and non-stress conditions. Eight heat-tolerant and two heat-sensitive bean genotypes, including common bean (P. vulgaris L.), tepary bean (P. acutifolius A. Gray), runner bean (P. coccineus L.), and lima bean (P. lunatus L.), were grown in the greenhouse. ABA, JA, and SA significantly varied among Phaseolus species and between heat-tolerant and heat-sensitive bean genotypes. ABA, JA, and SA contents were higher under heat-stress conditions than under non-stress conditions, suggesting that these stress-related hormones played a crucial role in survival strategy. In contrast, chlorophyll content and maximum quantum efficiency of PSII values were higher under non-stress conditions. Under non-stress conditions, the heat-tolerant genotypes commonly had lower JA and SA contents than the heat-sensitive genotypes, indicating that the heat-tolerant genotypes had a superior stress threshold. The lower JA and SA contents might be evaluated as selection criteria to discriminate heat-tolerant and heat-sensitive genotypes without exposure to heat stress. Additionally, path analysis was conducted to determine the direct and indirect effects of biochemical and physiological traits on chlorophyll content. The analysis revealed that the fold change in SA had the most significant positive direct effect on chlorophyll content, while the fold change in total phytohormones exhibited a strong negative direct effect. Indirect effects highlighted the complex interactions among phytohormones, particularly the antagonistic influence of ABA over SA. Besides, heat-tolerant genotypes had acquired unique adaptive characteristics to cope with heat stress, probably during the evolutionary process before domestication.

Cost-effective Phytohormone Extraction of Sargassum swartzii from the Persian Gulf Using Magnetic Ionic Liquid.

Algae extracts are utilized as biofertilizers instead of chemical ferti-lizers in agriculture. Further, algae are known to possess a high content of plant hormones, such as gibberellin, salicylic acid, abscisic acid, and brassinosteroids. The main objective of this study was to increase the extraction yield and simulta-neously extract hormones required for plant growth from Sargassum swartzii using Magnetic recoverable ionic liquid (IL). In this study, extraction was performed by acidic digestion with acetic acid and then alkaline digestion with potassium hydroxide. The results showed the ionic liquid effect in extraction yield by 266 percent. The extracted phytohormones were analyzed using high-performance liquid chromatography (HPLC) methods. High levels of gibberellin, salicylic acid, abscisic acid, and brassinosteroids in improved algae extraction showed that seaweed extract could be used as environmentally friendly liquid bio-fertilizers to replace chemical fertilizers and could play a crucial role in organic farming for sustainable agriculture. Additionally, the recoverability of ionic liquid eight times with negligible leaching proved the introduced procedure to be cost-effective. The reported procedure for algae extraction improved by using an acidic/primary ionic liquid environment. This procedure is economical because of the simple reusability of ionic liquid due to its magnetic features.

GATA8-Mediated Antiviral Defence Is Countered by Tomato Chlorosis Virus-Encoded Pathogenicity Protein p27.

Tomato chlorosis virus (ToCV), a phloem-restricted RNA virus within the genus Crinivirus of the family Closteroviridae, exhibits a broad host range and severely impacts the yield and quality of multiple crops. Viral infection directly alters endogenous phytohormone levels, which are intricately associated with viral mobility, replication, symptom development and defence mechanisms. Previous studies have demonstrated that GATA transcription factors regulate several hormone signalling pathways in plants. In this study, we explored the interaction between ToCV p27 and SlGATA8/NbGATA11. Results indicated that ToCV p27 interacts with an 18-amino-acid at the C-terminus of SlGATA8 and NbGATA11 proteins. Silencing and overexpressing of SlGATA8 revealed its positive role in regulating tomato defence against ToCV infection. Additionally, the interaction redirected SlGATA8's subcellular localisation to plasmodesmata.Furthermore, SlGATA8 promoted the transcriptional expression of SlSnRK2 to regulate the abscisic acid (ABA) signalling pathway. In conclusion, this study confirmed that ToCV p27 impaired the transcriptional activation activity of SlGATA8 through direct interaction, thereby inhibiting the ABA pathway and ultimately facilitating viral infection. This study established a link among virus, GATA family transcription factors and phytohormones, elucidating the molecular mechanism by which ToCV-encoded p27 protein interacts with SlGATA8 to disrupt ABA balance and promote virus infection.

Rice B2 and B3 subgroup RAF kinases play central roles in both ABA and osmotic stress signaling.

Rice B2 and B3 subgroup RAF kinases play central roles in both ABA and osmotic stress signaling.

Genome-wide identification of the HIPPs gene family and functional validation of MsHIPP12 in enhancing cadmium tolerance in Medicago sativa.

Genome-wide identification of the HIPPs gene family and functional validation of MsHIPP12 in enhancing cadmium tolerance in Medicago sativa.

Glandular trichome heads confer cadmium tolerance in Nicotiana tabacum L. via the co-regulation of JA and ABA signaling.

Glandular trichome heads confer cadmium tolerance in Nicotiana tabacum L. via the co-regulation of JA and ABA signaling.

Organic fertilizer mitigated the oxidative stress of tomato induced by nanoplastics through affecting rhizosphere soil microorganisms and bacteriophage functions.

Organic fertilizer mitigated the oxidative stress of tomato induced by nanoplastics through affecting rhizosphere soil microorganisms and bacteriophage functions.

Study on the mechanism of exogenous CaCl2 regulating cell growth and development to alleviate salt tolerance of alfalfa (Medicago sativa)

Salt stress affects the growth and development of alfalfa. Calcium Chloride (CaCl2) plays a role in signal transduction and stabilizing cell membrane system in plant response to salt stress. However, the regulatory effect of CaCl2 on the growth and development of alfalfa cells under Sodium Chloride (NaCl) stress is not clear. This study analyzed the response and mitigation mechanism of adding 1mM CaCl2 to alfalfa seedlings under 120 mM NaCl stress. The results showed that the addition of CaCl2 increased the germination rate, vigor index and root length of alfalfa under salt stress. Secondly, the addition of CaCl2 reduced the activity of peroxidase, which led to the decrease of hydrogen peroxide (H2O2) and Malondialdehyde (MDA) content and catalase (CAT) activity. From the perspective of anatomical structure, the addition of CaCl2 under salt stress did not promote the elongation growth of alfalfa, which mainly reduced the area of root and leaf cells. Transcription sequencing showed that phenylpropanoid biosynthesis, Mitogen-Activated Protein Kinase (MAPK) signal transduction and photosynthesis pathways played a key role in alleviating NaCl stress when CaCl2 was added under salt stress. The up-regulation of genes including peroxidase (POD), chitinase (ChiB) and Light-Harvesting Complex (LHC) could regulate lignin accumulation and ethylene, abscisic acid and H2O2 transfer to defend against salt stress. In conclusion, CaCl2 can regulate the morphological physiology and antioxidant system of alfalfa, effectively alleviate the adverse effects of salt stress, and provide a basis for exploring the regulation of salt tolerance and the mitigation of salt stress

Auxin and abscisic acid are involved in the regulation of soil moisture on thidiazuron-induced defoliation in cotton

Auxin and abscisic acid are involved in the regulation of soil moisture on thidiazuron-induced defoliation in cotton

Lead alters the tolerance of dominant woody plants in subtropical coastal zones to flash drought.

Lead alters the tolerance of dominant woody plants in subtropical coastal zones to flash drought.

Deciphering salt stress adaptation in octoploid broomcorn millet (Panicum miliaceum L.): For sustainable agricultural development in saline-alkaline soils.

Deciphering salt stress adaptation in octoploid broomcorn millet (Panicum miliaceum L.): For sustainable agricultural development in saline-alkaline soils.