scholarly journals Below versus above Ground Plant Sources of Abscisic Acid (ABA) at the Heart of Tropical Forest Response to Warming

2018 ◽  
Vol 19 (7) ◽  
pp. 2023 ◽  
Author(s):  
Israel Sampaio Filho ◽  
Kolby Jardine ◽  
Rosilena de Oliveira ◽  
Bruno Gimenez ◽  
Leticia Cobello ◽  
...  

Warming surface temperatures and increasing frequency and duration of widespread droughts threaten the health of natural forests and agricultural crops. High temperatures (HT) and intense droughts can lead to the excessive plant water loss and the accumulation of reactive oxygen species (ROS) resulting in extensive physical and oxidative damage to sensitive plant components including photosynthetic membranes. ROS signaling is tightly integrated with signaling mechanisms of the potent phytohormone abscisic acid (ABA), which stimulates stomatal closure leading to a reduction in transpiration and net photosynthesis, alters hydraulic conductivities, and activates defense gene expression including antioxidant systems. While generally assumed to be produced in roots and transported to shoots following drought stress, recent evidence suggests that a large fraction of plant ABA is produced in leaves via the isoprenoid pathway. Thus, through stomatal regulation and stress signaling which alters water and carbon fluxes, we highlight the fact that ABA lies at the heart of the Carbon-Water-ROS Nexus of plant response to HT and drought stress. We discuss the current state of knowledge of ABA biosynthesis, transport, and degradation and the role of ABA and other isoprenoids in the oxidative stress response. We discuss potential variations in ABA production and stomatal sensitivity among different plant functional types including isohydric/anisohydric and pioneer/climax tree species. We describe experiments that would demonstrate the possibility of a direct energetic and carbon link between leaf ABA biosynthesis and photosynthesis, and discuss the potential for a positive feedback between leaf warming and enhanced ABA production together with reduced stomatal conductance and transpiration. Finally, we propose a new modeling framework to capture these interactions. We conclude by discussing the importance of ABA in diverse tropical ecosystems through increases in the thermotolerance of photosynthesis to drought and heat stress, and the global importance of these mechanisms to carbon and water cycling under climate change scenarios.

Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1323 ◽  
Author(s):  
Shahid Ali ◽  
Kashif Hayat ◽  
Amjad Iqbal ◽  
Linan Xie

Drought is a severe environmental constraint, which significantly affects plant growth, productivity, and quality. Plants have developed specific mechanisms that perceive the stress signals and respond to external environmental changes via different mitigation strategies. Abscisic acid (ABA), being one of the phytohormones, serves as an important signaling mediator for plants’ adaptive response to a variety of environmental stresses. ABA triggers many physiological processes, including bud dormancy, seed germination, stomatal closure, and transcriptional and post-transcriptional regulation of stress-responsive gene expression. The site of its biosynthesis and action must be clarified to understand the signaling network of ABA. Various studies have documented multiple sites for ABA biosynthesis, their transporter proteins in the plasma membrane, and several components of ABA-dependent signaling pathways, suggesting that the ABA response to external stresses is a complex networking mechanism. Knowing about stress signals and responses will increase our ability to enhance crop stress tolerance through the use of various advanced techniques. This review will elaborate on the ABA biosynthesis, transportation, and signaling pathways at the molecular level in response to drought stress, which will add a new insight for future studies.


2021 ◽  
Author(s):  
Weiwei Gao ◽  
Mingkang Li ◽  
Songguang Yang ◽  
Chunzhi Gao ◽  
Yan Su ◽  
...  

AbstractInduced abscisic acid (ABA) biosynthesis plays an important role in plant tolerance to abiotic stresses, including drought, cold and salinity. However, regulation pathway of the ABA biosynthesis in response to stresses is unclear. Here, we identified a rice miRNA, osa-miR2105 (miR2105), which plays a crucial role in ABA biosynthesis under drought stress. Analysis of expression, transgenic rice and cleavage site showed that OsbZIP86 is a target gene of miR2105. Subcellular localization and luciferase activity assays showed that OsbZIP86 is a nuclear transcription factor. In vivo and in vitro analyses showed that OsbZIP86 directly binds to the promoter of OsNCED3, and interacts with OsSAPK10, resulting in enhanced-expression of OsNCED3. Transgenic rice plants with knock-down of miR2105 or overexpression of OsbZIP86 showed higher ABA content, more tolerance to drought, a lower rate of water loss, more stomatal closure than wild type rice ZH11 under drought stress. These rice plants showed no penalty with respect to agronomic traits under normal conditions. By contrast, transgenic rice plants with miR2105 overexpression, OsbZIP86 downregulation, or OsbZIP86 knockout displayed less tolerance to drought stress and other phenotypes. Collectively, our results show that a regulatory network of ‘miR2105-OsSAPK10/OsbZIP86-OsNCED3’ control ABA biosynthesis in response to drought stress.One-sentence summary‘miR2105-OsbZIP86-OsNCED3’ module plays crucial role in mediating ABA biosynthesis to contribute to drought tolerance with no penalty with respect to agronomic traits under normal conditions.


2013 ◽  
Vol 161 (3) ◽  
pp. 1158-1171 ◽  
Author(s):  
Hilde Van Houtte ◽  
Lies Vandesteene ◽  
Lorena López-Galvis ◽  
Liesbeth Lemmens ◽  
Ewaut Kissel ◽  
...  

2008 ◽  
Vol 148 (4) ◽  
pp. 2121-2133 ◽  
Author(s):  
Yu'e Zhang ◽  
Wenying Xu ◽  
Zhonghui Li ◽  
Xing Wang Deng ◽  
Weihua Wu ◽  
...  

2018 ◽  
Vol 115 (47) ◽  
pp. E11178-E11187 ◽  
Author(s):  
Hikaru Sato ◽  
Hironori Takasaki ◽  
Fuminori Takahashi ◽  
Takamasa Suzuki ◽  
Satoshi Iuchi ◽  
...  

The plant hormone abscisic acid (ABA) is accumulated after drought stress and plays critical roles in the responses to drought stress in plants, such as gene regulation, stomatal closure, seed maturation, and dormancy. Although previous reports revealed detailed molecular roles of ABA in stress responses, the factors that contribute to the drought-stress responses—in particular, regulation of ABA accumulation—remain unclear. The enzyme NINE-CIS-EPOXYCAROTENOID DIOXYGENASE 3 (NCED3) is essential for ABA biosynthesis during drought stress, and the NCED3 gene is highly induced by drought stress. In the present study, we isolated NGATHAs (NGAs) as candidate transcriptional regulators of NCED3 through a screen of a plant library harboring the transcription factors fused to a chimeric repressor domain, SRDX. The NGA proteins were directly bound to a cis-element NGA-binding element (NBE) in the 5′ untranslated region (5′ UTR) of the NCED3 promoter and were suggested to be transcriptional activators of NCED3. Among the single-knockout mutants of four NGA family genes, we found that the NGATHA1 (NGA1) knockout mutant was drought-stress-sensitive with a decreased expression level of NCED3 during dehydration stress. These results suggested that NGA1 essentially functions as a transcriptional activator of NCED3 among the NGA family proteins. Moreover, the NGA1 protein was degraded under nonstressed conditions, and dehydration stress enhanced the accumulation of NGA1 proteins, even in ABA-deficient mutant plants, indicating that there should be ABA-independent posttranslational regulations. These findings emphasize the regulatory mechanisms of ABA biosynthesis during early drought stress.


2021 ◽  
Vol 12 ◽  
Author(s):  
Qian Liu ◽  
Guang-rui Dong ◽  
Yu-qing Ma ◽  
Shu-man Zhao ◽  
Xi Liu ◽  
...  

Drought is one of the most important environmental constraints affecting plant growth and development and ultimately leads to yield loss. Uridine diphosphate (UDP)-dependent glycosyltransferases (UGTs) are believed to play key roles in coping with environmental stresses. In rice, it is estimated that there are more than 200 UGT genes. However, most of them have not been identified as their physiological significance. In this study, we reported the characterization of a putative glycosyltransferase gene UGT85E1 in rice. UGT85E1 gene is significantly upregulated by drought stress and abscisic acid (ABA) treatment. The overexpression of UGT85E1 led to an enhanced tolerance in transgenic rice plants to drought stress, while the ugt85e1 mutants of rice showed a more sensitive phenotype to drought stress. Further studies indicated that UGT85E1 overexpression induced ABA accumulation, stomatal closure, enhanced reactive oxygen species (ROS) scavenging capacity, increased proline and sugar contents, and upregulated expression of stress-related genes under drought stress conditions. Moreover, when UGT85E1 was ectopically overexpressed in Arabidopsis, the transgenic plants showed increased tolerance to drought as well as in rice. Our findings suggest that UGT85E1 plays an important role in mediating plant response to drought and oxidative stresses. This work may provide a promising candidate gene for cultivating drought-tolerant crops both in dicots and monocots.


2021 ◽  
Vol 12 ◽  
Author(s):  
Minchae Kim ◽  
Soongon Jeong ◽  
Chae Woo Lim ◽  
Sung Chul Lee

Protein phosphorylation by kinase is an important mechanism for adapting to drought stress conditions. Here, we isolated the CaDIMK1 (Capsicum annuum drought-induced MAP kinase 1) from dehydrated pepper leaf tissue and functionally characterized it. Subcellular localization analysis revealed that the CaDIMK1 protein was localized in the cytoplasm and nucleus. CaDIMK1-silenced pepper plants exhibited drought-susceptible phenotypes that were characterized by increased transpiration rates, low leaf temperatures, and decreased stomatal closure. In contrast, CaDIMK1-overexpressing (OX) transgenic Arabidopsis plants were hypersensitive to abscisic acid (ABA) from germination to adult growth stages. Furthermore, the CaDIMK1-OX plants were tolerant to drought stress. The transcript levels of several stress-related genes were high in CaDIMK1-OX plants than in wild-type plants. Taken together, our data demonstrate that CaDIMK1 acts as a positive modulator of drought tolerance and ABA signal transduction in pepper plants.


2021 ◽  
Author(s):  
Yansha Han ◽  
Dianqing Gong ◽  
Huilan Yi

Abstract Background and aims Sulfate, the main source of sulfur in natural soil, is critical for plant growth and development, as well as plant responses to environmental stress, including drought. However, our understanding of the detailed mechanisms of sulfate-modulated drought tolerance in crop plants is far from complete. In the present study, by using foxtail millet (Setaria italica L.), an emerging model crop, we investigated the possible mechanisms involved in sulfate-induced crop tolerance to drought stress. Methods A combination of biochemical and molecular approaches, as well as stomatal apertures analyses were applied to determine the effect of sulfate application on sulfur assimilation, ABA biosynthesis, and stomatal movement. Results Upon drought exposure, sulfate (4 mM) pretreatment significantly alleviated the decrease in relative water content in foxtail millet leaves. Exogenous sulfate increased endogenous sulfate content and markedly enhanced the enzyme activity of sulfite reductase (SiR) and O-acetylserine(thiol)lyase (OASTL), as well as levels of their transcripts, leading to an increase in cysteine (Cys) production in drought-stressed leaves. Furthermore, in comparison with drought stress alone, sulfate application significantly upregulated the transcriptional expression of SiABA3 and SiAAO3, which contributed to the increased ABA levels in the leaves of drought-stressed foxtail millet seedlings. Moreover, the addition of sulfate decreased stomatal aperture, thus resulting in reduced leaf water loss in foxtail millet exposed to drought. Conclusion Our data suggest that sulfate application was able to promote drought tolerance of foxtail millet plants, at least partially by increasing ABA biosynthesis and triggering stomatal closure.


2021 ◽  
Vol 12 ◽  
Author(s):  
Liru Cao ◽  
Xiaomin Lu ◽  
Guorui Wang ◽  
Qianjin Zhang ◽  
Xin Zhang ◽  
...  

Analyzing the transcriptome of maize leaves under drought stress and rewatering conditions revealed that transcription factors were involved in this process, among which ZmbZIP33 of the ABSCISIC ACID-INSENSITIVE 5-like protein 5 family was induced to significantly up-regulated. The functional mechanism of ZmbZIP33 in Abscisic acd (ABA) signaling pathway and its response to drought stress and rewatering has not been studied yet. The present study found that ZmbZIP33 contains a DNA-binding and dimerization domain, has transcriptional activation activity, and is highly homologous to SbABI1,SitbZIP68 and OsABA1. The expression of ZmbZIP33 is strongly up-regulated by drought, high salt, high temperature, and ABA treatments. Overexpression of ZmbZIP33 remarkably increased chlorophyll content and root length after drought stress and rewatering, and, moreover, cause an accumulation of ABA content, thereby improving drought resistance and recovery ability in Arabidopsis. However, silencing the expression of ZmbZIP33 (BMV-ZmbZIP33) remarkably decreased chlorophyll content, ABA content, superoxide dismutase and peroxidase activities, and increased stomatal opening and water loss rate compared with BMV (control). It showed that silencing ZmbZIP33 lead to reduced drought resistance and recovery ability of maize. ABA sensitivity analysis found that 0.5 and 1 μmol/L treatments severely inhibited the root development of overexpression ZmbZIP33 transgenic Arabidopsis. However, the root growth of BMV was greatly inhibited for 1 and 5μmol/L ABA treatments, but not for BMV-ZmbZIP33. Subcellular localization, yeast two-hybrid and BIFC further confirmed that the core components of ABA signaling pathways ZmPYL10 and ZmPP2C7 interacted in nucleus, ZmPP2C7 and ZmSRK2E as well as ZmSRK2E and ZmbZIP33 interacted in the plasma membrane. We also found that expression levels of ZmPYL10 and ZmSRK2E in the BMV-ZmbZIP33 mutant were lower than those of BMV, while ZmPP2C7 was the opposite under drought stress and rewatering. However, expression of ZmPYL10 and ZmSRK2E in normal maize leaves were significantly up-regulated by 3–4 folds after drought and ABA treatments for 24 h, while ZmPP2C7 was down-regulated. The NCED and ZEP encoding key enzymes in ABA biosynthesis are up-regulated in overexpression ZmbZIP33 transgenic line under drought stress and rewatering conditions, but down-regulated in BMV-ZmbZIP33 mutants. Together, these findings demonstrate that ZmbZIP33 played roles in ABA biosynthesis and regulation of drought response and rewatering in Arabidopsis and maize thought an ABA-dependent signaling pathway.


HortScience ◽  
2010 ◽  
Vol 45 (3) ◽  
pp. 409-413 ◽  
Author(s):  
Nicole L. Waterland ◽  
Craig A. Campbell ◽  
John J. Finer ◽  
Michelle L. Jones

Drought stress is a major cause of postproduction decline in bedding plants. The plant hormone abscisic acid (ABA) regulates drought stress responses by mediating stomatal closure, thereby reducing transpirational water loss. Exogenous ABA applications delay wilting and allow plants to survive short periods of severe drought. The effectiveness of the ABA biochemical, s-ABA (ConTego™; Valent BioSciences Corp., Libertyville, IL), at delaying wilting and extending shelf life during drought stress was evaluated in six bedding plant species. Spray and drench applications of 0 or 500 mg·L−1 s-ABA were applied to Impatiens walleriana (impatiens), Pelargonium ×hortorum (seed geranium), Petunia ×hybrida (petunia), Tagetes patula (marigold), Salvia splendens (salvia), and Viola ×wittrockiana (pansy). Water was subsequently withheld and wilting symptoms were compared between treated and control plants. s-ABA applications delayed wilting in all crops by 1.7 to 4.3 days. Leaf chlorosis was observed after s-ABA application in drought-stressed seed geraniums, marigolds, and pansies. In seed geraniums and marigolds, the drought stress itself resulted in leaf chlorosis that was equivalent to or more severe than the s-ABA application alone. In pansies, s-ABA applications induced leaf chlorosis that was more severe than the drought treatment. Overall, s-ABA was consistently effective at reducing water loss and extending shelf life for all species treated. Applications of s-ABA to bedding plants before shipping and retailing would allow plants to maintain marketability even under severe drought stress conditions.


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