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Mérai Z, Graeber K, Xu F, Donà M, Lalatović K, Wilhelmsson PKI, Fernandez-Pozo N, Rensing SA, Leubner-Metzger G, Mittelsten Scheid O, Dolan L. Long days induce adaptive secondary dormancy in the seeds of the Mediterranean plant Aethionema arabicum. Curr Biol 2024; 34:2893-2906.e3. [PMID: 38876102 DOI: 10.1016/j.cub.2024.05.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 03/18/2024] [Accepted: 05/22/2024] [Indexed: 06/16/2024]
Abstract
Secondary dormancy is an adaptive trait that increases reproductive success by aligning seed germination with permissive conditions for seedling establishment. Aethionema arabicum is an annual plant and member of the Brassicaceae that grows in environments characterized by hot and dry summers. Aethionema arabicum seeds may germinate in early spring when seedling establishment is permissible. We demonstrate that long-day light regimes induce secondary dormancy in the seeds of Aethionema arabicum (CYP accession), repressing germination in summer when seedling establishment is riskier. Characterization of mutants screened for defective secondary dormancy demonstrated that RGL2 mediates repression of genes involved in gibberellin (GA) signaling. Exposure to high temperature alleviates secondary dormancy, restoring germination potential. These data are consistent with the hypothesis that long-day-induced secondary dormancy and its alleviation by high temperatures may be part of an adaptive response limiting germination to conditions permissive for seedling establishment in spring and autumn.
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Affiliation(s)
- Zsuzsanna Mérai
- Gregor Mendel Institute of Molecular Plant Biology (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), 1030 Vienna, Austria.
| | - Kai Graeber
- Department of Biological Sciences, Royal Holloway University of London, Egham, SRY TW20 0EX, UK
| | - Fei Xu
- Gregor Mendel Institute of Molecular Plant Biology (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Mattia Donà
- Gregor Mendel Institute of Molecular Plant Biology (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Katarina Lalatović
- Gregor Mendel Institute of Molecular Plant Biology (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Per K I Wilhelmsson
- Plant Cell Biology, Faculty of Biology, University of Marburg, 35043 Marburg, Germany
| | - Noe Fernandez-Pozo
- Plant Cell Biology, Faculty of Biology, University of Marburg, 35043 Marburg, Germany; Institute for Mediterranean and Subtropical Horticulture "La Mayora" (IHSM-CSIC-UMA), 29010 Málaga, Spain
| | - Stefan A Rensing
- Plant Cell Biology, Faculty of Biology, University of Marburg, 35043 Marburg, Germany; Centre for Biological Signalling Studies (BIOSS), University of Freiburg, 79104 Freiburg, Germany
| | - Gerhard Leubner-Metzger
- Department of Biological Sciences, Royal Holloway University of London, Egham, SRY TW20 0EX, UK; Laboratory of Growth Regulators, Faculty of Science, Palacký University and Institute of Experimental Botany, Czech Academy of Sciences, 78371 Olomouc, Czech Republic
| | - Ortrun Mittelsten Scheid
- Gregor Mendel Institute of Molecular Plant Biology (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), 1030 Vienna, Austria
| | - Liam Dolan
- Gregor Mendel Institute of Molecular Plant Biology (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), 1030 Vienna, Austria
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Hao J, Tan J, Zhang Y, Gu X, Zhu G, Wang S, Li J. Sewage sludge-derived nutrients and biostimulants stimulate rice leaf photosynthesis and root metabolism to enhance carbohydrate, nitrogen and antioxidants accumulation. CHEMOSPHERE 2024; 352:141335. [PMID: 38301837 DOI: 10.1016/j.chemosphere.2024.141335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 02/03/2024]
Abstract
The production of high quality liquid nitrogen fertilizer with both nutrient comprehensive and biostimulant properties by alkaline thermal hydrolysis of sewage sludge has shown great potential in agricultural production. However, little is known about the effects of sewage sludge-derived nutrients, and biostimulants (SS-NB) on leaf photosynthesis and root growth in rice. Phenotypic, metabolic and microbial analyses were used to reveal the mechanism of SS-NB on rice. Compared to NF treatment, phenotypic parameters (fresh/dry weight, soluble sugar, amino acid, protein) were increased by SS-NB in rice. SS-NB can enhance the photosynthesis of rice leaves by improving the photoconversion efficiency, chlorophyll content, ATP synthase activity, Rubisco and NADPH production. Meanwhile, SS-NB also increased antioxidant capacity (SOD, POD, CAT and proline) in rice leaf and root tissues. Metabolomics revealed that SS-NB application increased the expression levels of metabolites in root and leaf tissues, including carbohydrate, nitrogen and sulfur metabolism, amino acid metabolism, antioxidants, and phytohormone. Most importantly, the regulation of metabolites in rice root tissues is more sensitive than in leaf tissues, especially to the higher levels of antioxidants and phytohormones (IAA and GA) in rice root tissues. Furthermore, SS-NB increased the abundance of photosynthetic autotrophic, organic acids-degrading and denitrifying functional bacteria in rice roots and recruited plant growth-promoting bacteria (Azospirillum and norank_f_JG30-KF-CM45), while the NF treatment group resulted in an imbalance of the microbial community, leading to the dominance of pathogenic bacteria. The results showed that SS-NB had great application potential in crop growth and stress resistance improvement.
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Affiliation(s)
- Jiahou Hao
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Ecology, Jiangnan University, Wuxi, 214122, China
| | - Jiayi Tan
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Ecology, Jiangnan University, Wuxi, 214122, China
| | - Yue Zhang
- China Civil Engineering Society Water Industry Association, Beijing, 100082, China
| | - Xuejia Gu
- Heilongjiang Academy of Black Soil Conservation and Utilization, Harbin, 150086, China
| | - Ge Zhu
- Wuxi Huilian Green Ecological Technology Co., LTD, Wuxi, 214100, China
| | - Shuo Wang
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Ecology, Jiangnan University, Wuxi, 214122, China; Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou, 215009, China.
| | - Ji Li
- Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environment and Ecology, Jiangnan University, Wuxi, 214122, China; Jiangsu College of Water Treatment Technology and Material Collaborative Innovation Center, Suzhou, 215009, China.
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Yang C, Li H, Liang H, Huang B, Sun Y, Yang W, Wu Y, Cui Y, Hai J, Dong Z. Stereoselectivity of paclobutrazol enantiomers to oxidative stress in wheat. Chirality 2024; 36:e23638. [PMID: 38384151 DOI: 10.1002/chir.23638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Revised: 12/11/2023] [Accepted: 12/19/2023] [Indexed: 02/23/2024]
Abstract
Chiral pesticides have the special chiral structures, so enantioselective biological effects are usually observed in living organisms. Current study used paclobutrazol as a case study and explored the enantioselective degradation and oxidative stress effect on wheat. The results demonstrated that the degradation of R-paclobutrazol was faster than S-paclobutrazol significantly and improved the content of MDA and O2 - in wheat plants, which proved that the R-paclobutrazol induced oxidative damage in wheat, showing selective biological effects, and S-paclobutrazol was friendly to wheat. This study provided a theoretical basis for the selective activity of chiral pesticides and the development of chiral pesticide monomers.
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Affiliation(s)
- Chao Yang
- College of Agronomy, Northwest A&F University, Xianyang, Shaanxi Province, People's Republic of China
| | - Hao Li
- College of Agronomy, Northwest A&F University, Xianyang, Shaanxi Province, People's Republic of China
| | - Huajun Liang
- Maanshan Agricultural and Rural Bureau, Xianyang, Shaanxi Province, People's Republic of China
| | - Bo Huang
- College of Agronomy, Northwest A&F University, Xianyang, Shaanxi Province, People's Republic of China
| | - Yitao Sun
- College of Agronomy, Northwest A&F University, Xianyang, Shaanxi Province, People's Republic of China
| | - Wenlong Yang
- College of Agronomy, Northwest A&F University, Xianyang, Shaanxi Province, People's Republic of China
| | - Yilun Wu
- College of Agronomy, Northwest A&F University, Xianyang, Shaanxi Province, People's Republic of China
| | - Youhe Cui
- College of Agronomy, Northwest A&F University, Xianyang, Shaanxi Province, People's Republic of China
| | - Jiangbo Hai
- College of Agronomy, Northwest A&F University, Xianyang, Shaanxi Province, People's Republic of China
| | - Zhoujia Dong
- Qinghai Tongren City Agriculture and Animal Husbandry Comprehensive Service Center, Xianyang, Shaanxi Province, People's Republic of China
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Fofana B, Soto-Cerda B, Zaidi M, Main D, Fillmore S. Genome-wide genetic architecture for plant maturity and drought tolerance in diploid potatoes. Front Genet 2024; 14:1306519. [PMID: 38357658 PMCID: PMC10864671 DOI: 10.3389/fgene.2023.1306519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 12/18/2023] [Indexed: 02/16/2024] Open
Abstract
Cultivated potato (Solanum tuberosum) is known to be highly susceptible to drought. With climate change and its frequent episodes of drought, potato growers will face increased challenges to achieving their yield goals. Currently, a high proportion of untapped potato germplasm remains within the diploid potato relatives, and the genetic architecture of the drought tolerance and maturity traits of diploid potatoes is still unknown. As such, a panel of 384 ethyl methanesulfonate-mutagenized diploid potato clones were evaluated for drought tolerance and plant maturity under field conditions. Genome-wide association studies (GWAS) were conducted to dissect the genetic architecture of the traits. The results obtained from the genetic structure analysis of the panel showed five main groups and seven subgroups. Using the Genome Association and Prediction Integrated Tool-mixed linear model GWAS statistical model, 34 and 17 significant quantitative trait nucleotides (QTNs) were found associated with maturity and drought traits, respectively. Chromosome 5 carried most of the QTNs, some of which were also detected by using the restricted two-stage multi-locus multi-allele-GWAS haploblock-based model, and two QTNs were found to be pleiotropic for both maturity and drought traits. Using the non-parametric U-test, one and three QTNs, with 5.13%-7.4% phenotypic variations explained, showed favorable allelic effects that increase the maturity and drought trait values. The quantitaive trait loci (QTLs)/QTNs associated with maturity and drought trait were found co-located in narrow (0.5-1 kb) genomic regions with 56 candidate genes playing roles in plant development and senescence and in abiotic stress responses. A total of 127 potato clones were found to be late maturing and tolerant to drought, while nine were early to moderate-late maturing and tolerant to drought. Taken together, the data show that the studied germplasm panel and the identified candidate genes are prime genetic resources for breeders and biologists in conventional breeding and targeted gene editing as climate adaptation tools.
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Affiliation(s)
- Bourlaye Fofana
- Charlottetown Research and Development Centre, Agriculture and Agri-Food Canada, Charlottetown, PE, Canada
| | - Braulio Soto-Cerda
- Departamento de Ciencias Agropecuarias y Acuícolas, Universidad Católica de Temuco, Temuco, Chile
- Núcleo de Investigación en Producción Alimentaria, Facultad de Recursos Naturales, Universidad Católica de Temuco, Temuco, Chile
| | - Moshin Zaidi
- Charlottetown Research and Development Centre, Agriculture and Agri-Food Canada, Charlottetown, PE, Canada
| | - David Main
- Charlottetown Research and Development Centre, Agriculture and Agri-Food Canada, Charlottetown, PE, Canada
| | - Sherry Fillmore
- Kentville Research and Development Centre, Agriculture and Agri-Food Canada, Kentville, NS, Canada
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Kępczyński J, Wójcik A, Dziurka M. NO-mediated dormancy release of Avena fatua caryopses is associated with decrease in abscisic acid sensitivity, content and ABA/GA s ratios. PLANTA 2023; 257:101. [PMID: 37087501 PMCID: PMC10122620 DOI: 10.1007/s00425-023-04117-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 03/07/2023] [Indexed: 05/03/2023]
Abstract
MAIN CONCLUSION NO releases caryopsis dormancy in Avena fatua, the effect being dependent on the level of dormancy. The NO effect involves also the reduction of caryopsis sensitivity to ABA and to a decrease in the ABA to GAs ratio due to a decrease in ABA levels and the lack of effect on GAs levels before germination is completed. Nitric oxide (NO) from various donors (i.e. SNP, GSNO and acidified KNO2), applied to dry caryopses or during initial germination, released primary dormancy in caryopses. Dormancy in caryopses was gradually lost during dry storage (after-ripening) at 25 °C, enabling germination at 20 °C in the dark. The after-ripening effect is associated with a decrease in NO required for germination. In addition, NO decreased the sensitivity of dormant caryopses to exogenous abscisic acid (ABA) and decreased the embryos' ABA content before germination was completed. However, NO did not affect the content of bioactive gibberellins (GAs) from non-13-hydroxylation (GA4, GA7) and 13-hydroxylation (GA1, GA3, GA6.) pathways. Paclobutrazol (PAC), commonly regarded as a GAs biosynthesis inhibitor, counteracted the dormancy-releasing effect of NO and did not affect the GAs level; however, it increased the ABA content in embryos before germination was completed. Ascorbic acid, sodium benzoate and tiron, scavengers of reactive oxygen species (ROS), reduced the stimulatory effect of NO on caryopsis germination. This work provides new insight on the participation of NO in releasing A. fatua caryopses dormancy and on the relationship of NO with endogenous ABA and GAs.
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Affiliation(s)
- Jan Kępczyński
- Institute of Biology, University of Szczecin, Wąska 13, 71-415, Szczecin, Poland.
| | - Agata Wójcik
- Institute of Biology, University of Szczecin, Wąska 13, 71-415, Szczecin, Poland
| | - Michał Dziurka
- Institute of Plant Physiology, Polish Academy of Sciences, Niezapominajek 21, 20-239, Krakow, Poland
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Khan AH, Min L, Ma Y, Zeeshan M, Jin S, Zhang X. High-temperature stress in crops: male sterility, yield loss and potential remedy approaches. PLANT BIOTECHNOLOGY JOURNAL 2023; 21:680-697. [PMID: 36221230 PMCID: PMC10037161 DOI: 10.1111/pbi.13946] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 10/06/2022] [Accepted: 10/10/2022] [Indexed: 05/16/2023]
Abstract
Global food security is one of the utmost essential challenges in the 21st century in providing enough food for the growing population while coping with the already stressed environment. High temperature (HT) is one of the main factors affecting plant growth, development and reproduction and causes male sterility in plants. In male reproductive tissues, metabolic changes induced by HT involve carbohydrates, lipids, hormones, epigenetics and reactive oxygen species, leading to male sterility and ultimately reducing yield. Understanding the mechanism and genes involved in these pathways during the HT stress response will provide a new path to improve crops by using molecular breeding and biotechnological approaches. Moreover, this review provides insight into male sterility and integrates this with suggested strategies to enhance crop tolerance under HT stress conditions at the reproductive stage.
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Affiliation(s)
- Aamir Hamid Khan
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanChina
| | - Ling Min
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanChina
| | - Yizan Ma
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanChina
| | - Muhammad Zeeshan
- Guangxi Key Laboratory for Agro‐Environment and Agro‐Product Safety, Guangxi Colleges and Universities Key Laboratory of Crop Cultivation and Tillage, College of AgricultureGuanxi UniversityNanningChina
| | - Shuangxia Jin
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanChina
| | - Xianlong Zhang
- National Key Laboratory of Crop Genetic Improvement & Hubei Hongshan LaboratoryHuazhong Agricultural UniversityWuhanChina
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Swain R, Sahoo S, Behera M, Rout GR. Instigating prevalent abiotic stress resilience in crop by exogenous application of phytohormones and nutrient. FRONTIERS IN PLANT SCIENCE 2023; 14:1104874. [PMID: 36844040 PMCID: PMC9947512 DOI: 10.3389/fpls.2023.1104874] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 01/12/2023] [Indexed: 05/29/2023]
Abstract
In recent times, the demand for food and feed for the ever-increasing population has achieved unparalleled importance, which cannot afford crop yield loss. Now-a-days, the unpleasant situation of abiotic stress triggers crop improvement by affecting the different metabolic pathways of yield and quality advances worldwide. Abiotic stress like drought, salinity, cold, heat, flood, etc. in plants diverts the energy required for growth to prevent the plant from shock and maintain regular homeostasis. Hence, the plant yield is drastically reduced as the energy is utilized for overcoming the stress in plants. The application of phytohormones like the classical auxins, cytokinins, ethylene, and gibberellins, as well as more recent members including brassinosteroids, jasmonic acids, etc., along with both macro and micronutrients, have enhanced significant attention in creating key benefits such as reduction of ionic toxicity, improving oxidative stress, maintaining water-related balance, and gaseous exchange modification during abiotic stress conditions. Majority of phytohormones maintain homeostasis inside the cell by detoxifying the ROS and enhancing the antioxidant enzyme activities which can enhance tolerance in plants. At the molecular level, phytohormones activate stress signaling pathways or genes regulated by abscisic acid (ABA), salicylic acid (SA), Jasmonic acid (JA), and ethylene. The various stresses primarily cause nutrient deficiency and reduce the nutrient uptake of plants. The application of plant nutrients like N, K, Ca, and Mg are also involved in ROS scavenging activities through elevating antioxidants properties and finally decreasing cell membrane leakage and increasing the photosynthetic ability by resynthesizing the chlorophyll pigment. This present review highlighted the alteration of metabolic activities caused by abiotic stress in various crops, the changes of vital functions through the application of exogenous phytohormones and nutrition, as well as their interaction.
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Affiliation(s)
- Rinny Swain
- Department of Agricultural Biotechnology, Crop Improvement Division, School of Agriculture, Gandhi University of Engineering and Technology (GIET) University, Rayagada, Odisha, India
| | - Smrutishree Sahoo
- Department of Genetics and Plant Breeding, Crop Improvement Division, School of Agriculture, GIET University, Rayagada, Odisha, India
| | - Mamata Behera
- Department of Genetics and Plant Breeding, Crop Improvement Division, School of Agriculture, GIET University, Rayagada, Odisha, India
| | - Gyana Ranjan Rout
- Department of Agricultural Biotechnology, College of Agriculture, Odisha University of Agriculture and Technology, Bhubaneswar, Odisha, India
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Islam MS, Hasan MK, Islam MR, Chowdhury MK, Pramanik MH, Iqbal MA, Rajendran K, Iqbal R, Soufan W, Kamran C, Liyun L, El Sabagh A. Water relations and yield characteristics of mungbean as influenced by foliar application of gibberellic acid (GA3). Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1048768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Optimizing the dose and foliar application frequency of growth regulators such as gibberellic acid (GA3) may play an important role in ensuring food security under changing climate scenarios by boosting grain yield of food legumes such as mungbean. A trial was conducted to evaluate the growth promoting effect of foliage applied gibberellic acid (GA3) at various spraying frequencies for mungbean crop. The employed treatments included four gibberellic acid levels (0, 100, 200, and 300 ppm) and two application frequencies (single spray at 30 days after sowing DAS, and two sprays at 30 and 40 DAS). Water relations, yield contributing characteristics and mungbean grain yield were among the response variables investigated. The research findings revealed that GA3 (200 ppm applied twice at pre-flowering and post-flowering stages) significantly improved the water relations, morphological and yield attributes of mungbean. This treatment combination remained unmatched by producing the highest relative water content in the stem (85.52), water retention capacity in the stem (17.24), and water uptake capacity in the stem and leaf (2.35). Furthermore, the same treatment combination resulted in the maximum plant height (50.04 cm), pods per plant (11.07), pod length (6.62 cm), grains number per pod (11.00), 100-grains weight (3.78 g), grain yield per plant (4.57 g), and a minimum water saturation deficit. Thus, GA3 foliage application at 200 ppm at 30 and 60 DAS has the potential to stimulate growth and increase the yield attributes and grain yield of mungbean. However, additional in-depth field trials with various doses of GA3 sprayed at a higher frequency may be required before recommending GA3 for general adoption to mungbean growers.
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Paclobutrazol Ameliorates Low-Light-Induced Damage by Improving Photosynthesis, Antioxidant Defense System, and Regulating Hormone Levels in Tall Fescue. Int J Mol Sci 2022; 23:ijms23179966. [PMID: 36077362 PMCID: PMC9456200 DOI: 10.3390/ijms23179966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 08/25/2022] [Accepted: 08/30/2022] [Indexed: 11/17/2022] Open
Abstract
Paclobutrazol (PBZ) is a plant-growth regulator (PGR) in the triazole family that enhances plant tolerance to environmental stresses. Low-light (LL) intensity is a critical factor adversely affecting the growth of tall fescue (Festuca arundinacea Schreb.). Therefore, in this study, tall fescue seedlings were treated with PBZ under control and LL conditions to investigate the effects of PBZ on enhancing LL stress resistance by regulating the growth, photosynthesis, oxidative defense, and hormone levels. Our results reveal that LL stress reduced the total biomass, chlorophyll (Chl) content, photosynthetic capacity, and photochemical efficiency of photosystem II (PSII) but increased the membrane lipid peroxidation level and reactive oxygen species (ROS) generation. However, the application of PBZ increased the photosynthetic pigment contents, net photosynthetic rate (Pn), maximum quantum yield of PSII photochemistry (Fv/Fm), ribulose-1,5-bisphosphate carboxylase (RuBisCO) activity, and starch content. In addition, PBZ treatment activated the antioxidant enzyme activities, antioxidants contents, ascorbate acid-glutathione (AsA-GSH) cycle, and related gene expression, lessening the ROS burst (H2O2 and O2∙−). However, the gibberellic acid (GA) anabolism was remarkably decreased by PBZ treatment under LL stress, downregulating the transcript levels of kaurene oxidase (KO), kaurenoic acid oxidase (KAO), and GA 20-oxidases (GA20ox). At the same time, PBZ treatment up-regulated 9-cis-epoxycarotenoid dioxygenase (NCED) gene expression, significantly increasing the endogenous abscisic acid (ABA) concentration under LL stress. Thus, our study revealed that PBZ improves the antioxidation and photosynthetic capacity, meanwhile increasing the ABA concentration and decreasing GA concentration, which ultimately enhances the LL stress tolerance in tall fescue.
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