Browsing by Author "Li, Weiqiang"
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Item Cytokinin and MAX2 signaling pathways act antagonistically in drought adaptation of Arabidopsis thaliana(2024) Nguyen, Kien Huu; Li, Zihan; Wang, Chengliang; Van Ha, Chien (TTU); Tran, Cuong Duy; Abdelrahman, Mostafa (TTU); Pham, Xuan Hoi; Trung, Khuat Huu; Khanh, Tran Dang; Chu, Ha Duc; Mostofa, Mohammad Golam; Watanabe, Yasuko; Wang, Yaping; Miao, Yuchen; Mochida, Keiichi; Pal, Sikander; Li, Weiqiang; Tran, Lam Son Phan (TTU)Understanding the mechanisms, especially those associated with phytohormones, of plant drought adaptation is crucial for sustaining agricultural production in the era of climate change. Arabidopsis histidine kinases (AHKs), an integral part of the cytokinin signaling pathway, and more axillary growth 2 (MAX2), a key component of the strigolactone and karrikin signaling pathways are reported to act as negative and positive regulators, respectively, in plant adaption to drought. However, the potential interaction between these singaling pathways in plant drought adaptation is not fully understood. To address this query, we assessed drought tolerance levels and associated phenotypic and physiological traits of the max2 single mutant, ahk2 ahk3 double mutant, ahk2 ahk3 max2 triple mutant, and wild-type (WT) Arabidopsis thaliana plants. Our findings revealed a distinct hierarchy in drought tolerance among these genotypes, as indicated by the differences in plant growth and stress survival rates. Specifically, the max2 mutant displayed the lowest drought tolerance level, followed by WT, ahk2 ahk3 max2, and ahk2 ahk3 plants. Additionally, the observed changes in leaf relative water content, leaf surface temperature, and cuticle formation were coherently aligned with the observed hierarchy of drought tolerance levels. Under drought conditions, the max2 mutant exhibited higher oxidative stress and membrane damage, as evidenced by increased levels of reactive oxygen species (ROS), malondialdehyde, and electrolyte leakage. In contrast, the ahk2 ahk3 and ahk2 ahk3 max2 mutants showed low and intermediate levels, respectively, for these parameters. The max2 mutant displayed reduced sensitivity, whereas ahk2 ahk3 and ahk2 ahk3 max2 mutants demonstrated high and intermediate sensitivities, respectively, to exogenous abscisic acid (ABA) treatments. Additionally, the expression analysis of several genes associated with the investigated drought tolerance-related traits showed a positive correlation between the transcript levels and corresponding trait(s) in both mutant and WT plants under drought conditions. Our results collectively indicate the presence of an antagonistic interaction between AHK and MAX2 signaling pathways in plant drought adaptation, impacting ABA responsiveness, leaf water retention, cuticle development, and ROS homestasis. The findings of this study provide a valuable foundation for developing agricultural methods to improve plant drought resilience.Item Defective cytokinin signaling reprograms lipid and flavonoid gene-to-metabolite networks to mitigate high salinity in Arabidopsis(2021) Abdelrahman, Mostafa; Nishiyama, Rie; Tran, Cuong Duy; Kusano, Miyako; Nakabayashi, Ryo; Okazaki, Yozo; Matsuda, Fumio; Chávez Montes, Ricardo A. (TTU); Mostofa, Mohammad Golam (TTU); Li, Weiqiang; Watanabe, Yasuko; Fukushima, Atsushi; Tanaka, Maho; Seki, Motoaki; Saito, Kazuki; Herrera-Estrella, Luis (TTU); Tran, Lam-Son Phan (TTU)Cytokinin (CK) in plants regulates both developmental processes and adaptation to environmental stresses. Arabidopsis histidine phosphotransfer ahp2,3,5 and type-B Arabidopsis response regulator arr1,10,12 triple mutants are almost completely defective in CK signaling, and the ahp2,3,5 mutant was reported to be salt tolerant. Here, we demonstrate that the arr1,10,12 mutant is also more tolerant to salt stress than wild-type (WT) plants. A comprehensive metabolite profiling coupled with transcriptome analysis of the ahp2,3,5 and arr1,10,12 mutants was conducted to elucidate the salt tolerance mechanisms mediated by CK signaling. Numerous primary (e.g., sugars, amino acids, and lipids) and secondary (e.g., flavonoids and sterols) metabolites accumulated in these mutants under nonsaline and saline conditions, suggesting that both prestress and poststress accumulations of stress-related metabolites contribute to improved salt tolerance in CK-signaling mutants. Specifically, the levels of sugars (e.g., trehalose and galactinol), amino acids (e.g., branched-chain amino acids and γ-aminobutyric acid), anthocyanins, sterols, and unsaturated triacylglycerols were higher in the mutant plants than in WT plants. Notably, the reprograming of flavonoid and lipid pools was highly coordinated and concomitant with the changes in transcriptional levels, indicating that these metabolic pathways are transcriptionally regulated by CK signaling. The discovery of the regulatory role of CK signaling on membrane lipid reprogramming provides a greater understanding of CK-mediated salt tolerance in plants. This knowledge will contribute to the development of salt-tolerant crops with the ability to withstand salinity as a key driver to ensure global food security in the era of climate crisis.Item Driving factor analysis of ecosystem service balance for watershed management in the Lancang river valley, Southwest China(2021) Liu, Shiliang; Sun, Yongxiu; Wu, Xue; Li, Weiqiang; Liu, Yixuan; Tran, Lam Son Phan (TTU)Revealing the spatio-temporal change of the supply, demand and balance of ecosystem services (ESs) associated with human activities and land-use changes is of great significance for watershed ecosystem management. Taking the Lancang river valley as a case, we explicitly studied the ES spatial characteristics, using the land use/land cover (LULC) matrix model, Optimized Hot Spot Analysis and landscape pattern analysis. Furthermore, we screened out the dominant explanatory variables that had significant influence on the ES supply, demand and balance by means of the Geographical Weighted Regression (GWR) method at pixel scale. The results showed that the ES demand intensity varied little throughout the watershed, while the downstream ES supply capacity and balance values were greater than upstream ones. Meanwhile, the hotspots of ES supply and demand were mainly distributed in the south part with coldspots in the north part. Human activity factors integrating landscape pattern variables were verified to have a negative impact on the ES balance in general. Among them, the Largest Patch Index (LPI) had a negative influence on the majority of pixels, while the Gross Domestic Product (GDP), cultivated land ratio and Area Weighted Average Patch Fractal Dimension (AWAPFD) had positive effects on a few pixels. This study will provide scientific support for regional ecosystem service trade-off and regulation at multiple scales.Item Identification of bZIP Transcription Factors That Regulate the Development of Leaf Epidermal Cells in Arabidopsis thaliana by Single-Cell RNA Sequencing(2024) Wu, Rui; Liu, Zhixin; Sun, Susu; Qin, Aizhi; Liu, Hao; Zhou, Yaping; Li, Weiqiang; Liu, Yumeng; Hu, Mengke; Yang, Jincheng; Rochaix, Jean David; An, Guoyong; Herrera-Estrella, Luis (TTU); Tran, Lam Son Phan (TTU); Sun, XuwuEpidermal cells are the main avenue for signal and material exchange between plants and the environment. Leaf epidermal cells primarily include pavement cells, guard cells, and trichome cells. The development and distribution of different epidermal cells are tightly regulated by a complex transcriptional regulatory network mediated by phytohormones, including jasmonic acid, and transcription factors. How the fate of leaf epidermal cells is determined, however, is still largely unknown due to the diversity of cell types and the complexity of their regulation. Here, we characterized the transcriptional profiles of epidermal cells in 3-day-old true leaves of Arabidopsis thaliana using single-cell RNA sequencing. We identified two genes encoding BASIC LEUCINE-ZIPPER (bZIP) transcription factors, namely bZIP25 and bZIP53, which are highly expressed in pavement cells and early-stage meristemoid cells. Densities of pavement cells and trichome cells were found to increase and decrease, respectively, in bzip25 and bzip53 mutants, compared with wild-type plants. This trend was more pronounced in the presence of jasmonic acid, suggesting that these transcription factors regulate the development of trichome cells and pavement cells in response to jasmonic acid.Item Medicago sativa and Medicago truncatula Show Contrasting Root Metabolic Responses to Drought(2021) Echeverria, Andres; Larrainzar, Estíbaliz; Li, Weiqiang; Watanabe, Yasuko; Sato, Muneo; Tran, Cuong Duy; Moler, Jose A.; Hirai, Masami Yokota; Sawada, Yuji; Tran, Lam Son Phan (TTU); Gonzalez, Esther M.Drought is an environmental stressor that affects crop yield worldwide. Understanding plant physiological responses to stress conditions is needed to secure food in future climate conditions. In this study, we applied a combination of plant physiology and metabolomic techniques to understand plant responses to progressive water deficit focusing on the root system. We chose two legume plants with contrasting tolerance to drought, the widely cultivated alfalfa Medicago sativa (Ms) and the model legume Medicago truncatula (Mt) for comparative analysis. Ms taproot (tapR) and Mt fibrous root (fibR) biomass increased during drought, while a progressive decline in water content was observed in both species. Metabolomic analysis allowed the identification of key metabolites in the different tissues tested. Under drought, carbohydrates, abscisic acid, and proline predominantly accumulated in leaves and tapRs, whereas flavonoids increased in fibRs in both species. Raffinose-family related metabolites accumulated during drought. Along with an accumulation of root sucrose in plants subjected to drought, both species showed a decrease in sucrose synthase (SUS) activity related to a reduction in the transcript level of SUS1, the main SUS gene. This study highlights the relevance of root carbon metabolism during drought conditions and provides evidence on the specific accumulation of metabolites throughout the root system.Item Positive roles of the Ca2+ sensors GbCML45 and GbCML50 in improving cotton Verticillium wilt resistance(2024) Yi, Feifei; Li, Yuzhe; Song, Aosong; Shi, Xinying; Hu, Shanci; Wu, Shuang; Shao, Lili; Chu, Zongyan; Xu, Kun; Li, Liangliang; Tran, Lam Son Phan (TTU); Li, Weiqiang; Cai, YingfanAs a universal second messenger, cytosolic calcium (Ca2+) functions in multifaceted intracellular processes, including growth, development and responses to biotic/abiotic stresses in plant. The plant-specific Ca2+ sensors, calmodulin and calmodulin-like (CML) proteins, function as members of the second-messenger system to transfer Ca2+ signal into downstream responses. However, the functions of CMLs in the responses of cotton (Gossypium spp.) after Verticillium dahliae infection, which causes the serious vascular disease Verticillium wilt, remain elusive. Here, we discovered that the expression level of GbCML45 was promoted after V. dahliae infection in roots of cotton, suggesting its potential role in Verticillium wilt resistance. We found that knockdown of GbCML45 in cotton plants decreased resistance while overexpression of GbCML45 in Arabidopsis thaliana plants enhanced resistance to V. dahliae infection. Furthermore, there was physiological interaction between GbCML45 and its close homologue GbCML50 by using yeast two-hybrid and bimolecular fluorescence assays, and both proteins enhanced cotton resistance to V. dahliae infection in a Ca2+-dependent way in a knockdown study. Detailed investigations indicated that several defence-related pathways, including salicylic acid, ethylene, reactive oxygen species and nitric oxide signalling pathways, as well as accumulations of lignin and callose, are responsible for GbCML45- and GbCML50-modulated V. dahliae resistance in cotton. These results collectively indicated that GbCML45 and GbCML50 act as positive regulators to improve cotton Verticillium wilt resistance, providing potential targets for exploitation of improved Verticillium wilt-tolerant cotton cultivars by genetic engineering and molecular breeding.Item Sclerotinia sclerotiorum (Lib.) de Bary: Insights into the Pathogenomic Features of a Global Pathogen(2023) Hossain, Md Motaher; Sultana, Farjana; Li, Weiqiang; Tran, Lam Son Phan (TTU); Mostofa, Mohammad GolamSclerotinia sclerotiorum (Lib.) de Bary is a broad host-range fungus that infects an inclusive array of plant species and afflicts significant yield losses globally. Despite being a notorious pathogen, it has an uncomplicated life cycle consisting of either basal infection from myceliogenically germinated sclerotia or aerial infection from ascospores of carpogenically germinated sclerotia. This fungus is unique among necrotrophic pathogens in that it inevitably colonizes aging tissues to initiate an infection, where a saprophytic stage follows the pathogenic phase. The release of cell wall-degrading enzymes, oxalic acid, and effector proteins are considered critical virulence factors necessary for the effective pathogenesis of S. sclerotiorum. Nevertheless, the molecular basis of S. sclerotiorum pathogenesis is still imprecise and remains a topic of continuing research. Previous comprehensive sequencing of the S. sclerotiorum genome has revealed new insights into its genome organization and provided a deeper comprehension of the sophisticated processes involved in its growth, development, and virulence. This review focuses on the genetic and genomic aspects of fungal biology and molecular pathogenicity to summarize current knowledge of the processes utilized by S. sclerotiorum to parasitize its hosts. Understanding the molecular mechanisms regulating the infection process of S. sclerotiorum will contribute to devising strategies for preventing infections caused by this destructive pathogen.