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"Guo, Jiu-Xin"
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Adaptive responses of carbon and nitrogen metabolisms to nitrogen-deficiency in Citrus sinensis seedlings
Background
In China, nitrogen (N)-deficiency often occurs in
Citrus
orchards, which is one of the main causes of yield loss and fruit quality decline. Little information is known about the adaptive responses of
Citrus
carbon (C) and N metabolisms to N-deficiency. Seedlings of ‘Xuegan’ (
Citrus sinensis
(L.) Osbeck) were supplied with nutrient solution at an N concentration of 0 (N-deficiency), 5, 10, 15 or 20 mM for 10 weeks. Thereafter, we examined the effects of N supply on the levels of C and N in roots, stems and leaves, and the levels of organic acids, nonstructural carbohydrates, NH
4
+
-N, NO
3
−
-N, total soluble proteins, free amino acids (FAAs) and derivatives (FAADs), and the activities of key enzymes related to N assimilation and organic acid metabolism in roots and leaves.
Results
N-deficiency elevated sucrose export from leaves to roots, C and N distributions in roots and C/N ratio in roots, stems and leaves, thus enhancing root dry weight/shoot dry weight ratio and N use efficiency. N-deficient leaves displayed decreased accumulation of starch and total nonstructural carbohydrates (TNC) and increased sucrose/starch ratio as well as a partitioning trend of assimilated C toward to sucrose, but N-deficient roots displayed elevated accumulation of starch and TNC and reduced sucrose/starch ratio as well as a partitioning trend of assimilated C toward to starch. N-deficiency reduced the concentrations of most FAADs and the ratios of total FAADs (TFAADs)/N in leaves and roots. N-deficiency reduced the demand for C skeleton precursors for amino acid biosynthesis, thus lowering TFAADs/C ratio in leaves and roots. N-deficiency increased (decreased) the relative amounts of C-rich (N-rich) FAADs, thus increasing the molar ratio of C/N in TFAADs in leaves and roots.
Conclusions
Our findings corroborated our hypothesis that C and N metabolisms displayed adaptive responses to N-deficiency in
C. sinensis
seedlings, and that some differences existed between roots and leaves in N-deficiency-induced alterations of and C and N metabolisms.
Journal Article
فهم الصين : السجلات الكاملة للدورة الثانية من المؤتمر الدولي \فهم الصين\
الوقوف على كافة مجريات وتطورات الواقع الصيني فيما يتعلق بسياسات الحزب الشيوعي الصيني بوجه عام، والأوضاع الاقتصادية بالصين على الصعيدين المحلي والدولي، ليس بالأمر الهين على الباحثين والأكاديميين بل والمهتمين بالشأن الصيني عموما، لذا فإن هذا الكتاب \"فهم الصين\" يعد محطة مهمة في قراءة وفهم حاضر الصين ومستقبلها القريب والبعيد على حد سواء، حيث يكتسب هذا الكتاب خصوصيته وأهميته، من كونه يتألف من عدة أوراق بحثية وكلمات لأهم القادة السياسيين الصينيين والدوليين كل من منطلق موقعه السياسي، والذين ألقوا كلماتهم على هامش أهم حدث سياسي يحدث في الصين كل خمس سنوات، وهو اجتماع اللجنة المركزية للحزب الشيوعي الصيني في دورته الثامنة عشرة. ويتناول هذا الكتاب عددا من المحاور الأساسية فيما يتعلق بالسياسة الخارجية للصين، ودورها الاقتصادي إقليميا وعالميا، منها : استراتيجية التنمية الاقتصادية وتعزيز التنمية المنسقة في إطار الخطة الخمسية الثالثة عشرة للصين، وتحسين الحوكمة العالمية وبناء مجتمع المصالح المشتركة على نحو شامل وكذلك المشاركة الفعالة في الحوكمة الاقتصادية العالمية والسعي لتحقيق تنمية سلمية مشتركة، وإدارة الفضاء السيبراني في الصين، بالإضافة إلى استراتيجية الدفاع الوطني الصينية، وتعزيز حماية البيئة الإيكولوجية وبناء مجتمع رغد الحياة بشكل شامل، بالإضافة إلى تحليل وعرض لمستقبل مبادرة \"الحزام والطريق\" في ظل النظام العالمي الجديد.
Book
Responses of reactive oxygen species and methylglyoxal metabolisms to magnesium-deficiency differ greatly among the roots, upper and lower leaves of Citrus sinensis
Background
Magnesium (Mg)-deficiency is one of the most prevalent physiological disorders causing a reduction in
Citrus
yield and quality. ‘Xuegan’ (
Citrus sinensis
) seedlings were irrigated for 16 weeks with nutrient solution containing 2 mM (Mg-sufficiency) or 0 mM (Mg-deficiency) Mg(NO
3
)
2
. Thereafter, we investigated the Mg-deficient effects on gas exchange and chlorophyll a fluorescence in the upper and lower leaves, and Mg, reactive oxygen species (ROS) and methylglyoxal (MG) metabolisms in the roots, lower and upper leaves. The specific objectives were to corroborate the hypothesis that the responses of ROS and MG metabolisms to Mg-deficiency were greater in the lower leaves than those in the upper leaves, and different between the leaves and roots.
Results
Mg level was higher in the Mg-deficient upper leaves than that in the Mg-deficient lower leaves. This might be responsible for the Mg-deficiency-induced larger alterations of all the measured parameters in the lower leaves than those in the upper leaves, but they showed similar change patterns between the Mg-deficient lower and upper leaves. Accordingly, Mg-deficiency increased greatly their differences between the lower and upper leaves. Most of parameters involved in ROS and MG metabolisms had similar variation trends and degrees between the Mg-deficient lower leaves and roots, but several parameters (namely glutathione S-transferase, sulfite reductase, ascorbate and dehydroascorbate) displayed the opposite variation trends. Obviously, differences existed in the Mg-deficiency-induced alterations of ROS and MG metabolisms between the lower leaves and roots. Although the activities of most antioxidant and sulfur metabolism-related enzymes and glyoxalase I and the level of reduced glutathione in the Mg-deficient leaves and roots and the level of ascorbate in the leaves were kept in higher levels, the levels of malonaldehyde and MG and/or electrolyte leakage were increased in the Mg-deficient lower and upper leaves and roots, especially in the Mg-deficient lower leaves and roots.
Conclusions
The ROS and MG detoxification systems as a whole did not provide sufficient detoxification capacity to prevent the Mg-deficiency-induced production and accumulation of ROS and MG, thus leading to lipid peroxidation and the loss of plasma membrane integrity, especially in the lower leaves and roots.
Journal Article
Magnesium-Deficiency Effects on Pigments, Photosynthesis and Photosynthetic Electron Transport of Leaves, and Nutrients of Leaf Blades and Veins in Citrus sinensis Seedlings
Citrus sinensis seedlings were irrigated with nutrient solution at a concentration of 0 (Mg-deficiency) or 2 (Mg-sufficiency) mM Mg (NO3)2 for 16 weeks. Mg-deficiency-induced interveinal chlorosis, vein enlargement and corkiness, and alterations of gas exchange, pigments, chlorophyll a fluorescence (OJIP) transients and related parameters were observed in middle and lower leaves, especially in the latter, but not in upper leaves. Mg-deficiency might impair the whole photosynthetic electron transport, including structural damage to thylakoids, ungrouping of photosystem II (PSII), inactivation of oxygen-evolving complex (OEC) and reaction centers (RCs), increased reduction of primary quinone electron acceptor (QA) and plastoquinone pool at PSII acceptor side and oxidation of PSI end-electron acceptors, thus lowering energy transfer and absorption efficiency and the transfer of electrons to the dark reactions, hence, the rate of CO2 assimilation in Mg-deficiency middle and lower leaves. Although potassium, Mg, manganese and zinc concentration in blades displayed a significant and positive relationship with the corresponding element concentration in veins, respectively, great differences existed in Mg-deficiency-induced alterations of nutrient concentrations between leaf blades and veins. For example, Mg-deficiency increased boron level in the blades of upper leaves, decreased boron level in the blades of lower leaves, but did not affect boron level in the blades of middle leaves and veins of upper, middle and lower leaves. To conclude, Mg-deficiency-induced interveinal chlorosis, vein enlargement, and corkiness, and alterations to photosynthesis and related parameters increased with increasing leaf age. Mg-deficiency-induced enlargement and corkiness of veins were not caused by Mg-deficiency-induced boron-starvation.
Journal Article
Low pH effects on reactive oxygen species and methylglyoxal metabolisms in Citrus roots and leaves
Background
Limited data are available on the responses of reactive oxygen species (ROS) and methylglyoxal (MG) metabolisms to low pH in roots and leaves. In China, quite a few of
Citrus
are cultivated in acidic soils (pH < 5.0). ‘Xuegan’ (
Citrus sinensis
) and ‘Sour pummelo’ (
Citrus grandis
) (
C. sinensis
were more tolerant to low pH than
C. grandis
) seedlings were irrigated daily with nutrient solution at a pH of 2.5, 3 or 5 for nine months. Thereafter, we examined low pH effects on growth, and superoxide anion production rate (SAP), malondialdehyde (MDA), MG, antioxidants, and enzymes related to ROS and MG detoxification in roots and leaves in order to (
a
) test the hypothesis that low pH affected ROS and MG metabolisms more in roots than those of leaves, and (
b
) understand the roles of ROS and MG metabolisms in
Citrus
low pH-tolerance and -toxicity.
Results
Compared with control, most of the physiological parameters related to ROS and MG metabolisms were greatly altered at pH 2.5, but almost unaffected at pH 3. In addition to decreased root growth, many fibrous roots became rotten and died at pH 2.5. pH 2.5-induced changes in SAP, the levels of MDA, MG and antioxidants, and the activities of most enzymes related to ROS and MG metabolisms were greater in roots than those of leaves. Impairment of root ascorbate metabolism was the most serious, especially in
C. grandis
roots. pH 2.5-induced increases in MDA and MG levels in roots and leaves, decreases in the ratios of ascorbate/(ascorbate+dehydroascorbate) in roots and leaves and of reduced glutathione/(reduced+oxidized glutathione) in roots were greater in
C. grandis
than those in
C. sinensis
.
Conclusions
Low pH affected MG and ROS metabolisms more in roots than those in leaves. The most seriously impaired ascorbate metabolism in roots was suggested to play a role in low pH-induced root death and growth inhibition. Low pH-treated
C. sinensis
roots and leaves had higher capacity to maintain a balance between ROS and MG production and their removal via detoxification systems than low pH-treated
C. grandis
ones, thus contribute to the higher acid-tolerance of
C. sinensis
.
Journal Article
Magnesium Deficiency Induced Global Transcriptome Change in Citrus sinensis Leaves Revealed by RNA-Seq
Magnesium (Mg) deficiency is one of the major constraining factors that limit the yield and quality of agricultural products. Uniform seedlings of the Citrus sinensis were irrigated with Mg deficient (0 mM MgSO4) and Mg sufficient (1 mM MgSO4) nutrient solutions for 16 weeks. CO2 assimilation, starch, soluble carbohydrates, TBARS content and H2O2 production were measured. Transcriptomic analysis of C. sinensis leaves was performed by Illumina sequencing. Our results showed that Mg deficiency decreased CO2 assimilation, but increased starch, sucrose, TBARS content and H2O2 production in C. sinensis leaves. A total of 4864 genes showed differential expression in response to Mg deficiency revealed by RNA-Seq and the transcriptomic data were further validated by real-time quantitative PCR (RT-qPCR). Gene ontology (GO) enrichment analysis indicated that the mechanisms underlying Mg deficiency tolerance in C. sinensis may be attributed to the following aspects: (a) enhanced microtubule-based movement and cell cycle regulation; (b) elevated signal transduction in response to biotic and abiotic stimuli; (c) alteration of biological processes by tightly controlling phosphorylation especially protein phosphorylation; (d) down-regulation of light harvesting and photosynthesis due to the accumulation of carbohydrates; (e) up-regulation of cell wall remodeling and antioxidant system. Our results provide a comprehensive insight into the transcriptomic profile of key components involved in the Mg deficiency tolerance in C. sinensis and enrich our understanding of the molecular mechanisms by which plants adapted to a Mg deficient condition.
Journal Article
FGF21 ameliorates the neurocontrol of blood pressure in the high fructose-drinking rats
Fibroblast growth factor-21 (FGF21) is closely related to various metabolic and cardiovascular disorders. However, the direct targets and mechanisms linking FGF21 to blood pressure control and hypertension are still elusive. Here we demonstrated a novel regulatory function of FGF21 in the baroreflex afferent pathway (the nucleus tractus solitarii, NTS; nodose ganglion, NG). As the critical co-receptor of FGF21, β-klotho (klb) significantly expressed on the NTS and NG. Furthermore, we evaluated the beneficial effects of chronic intraperitoneal infusion of recombinant human FGF21 (rhFGF21) on the dysregulated systolic blood pressure, cardiac parameters, baroreflex sensitivity (BRS) and hyperinsulinemia in the high fructose-drinking (HFD) rats. The BRS up-regulation is associated with Akt-eNOS-NO signaling activation in the NTS and NG induced by acute intravenous rhFGF21 administration in HFD and control rats. Moreover, the expressions of FGF21 receptors were aberrantly down-regulated in HFD rats. In addition, the up-regulated peroxisome proliferator-activated receptor-γ and -α (PPAR-γ/-α) in the NTS and NG in HFD rats were markedly reversed by chronic rhFGF21 infusion. Our study extends the work of the FGF21 actions on the neurocontrol of blood pressure regulations through baroreflex afferent pathway in HFD rats.
Journal Article
Refining Nature in Modern Japanese Literature
This book examines the literature of Shiga Naoya, who is highly regarded in modern Japan for his unique style and methods of describing his personal experiences and emotions. Contributing new findings to the field of scholarship on Shiga, this study focuses in particular on Shiga’s nature-inspired writings and discusses how he created some vivid images of nature that became famous and still linger in Japanese people’s minds. Shiga’s remarkable sensitivity toward nature and the influences he received from earlier writers in Japan and abroad is examined. The complexity and depth of his understanding of nature is further revealed in his fascination with the supernatural, which also contributed to the creation of his literary style.
eBook
Four Decades of Poverty Reduction in China
Regardless of the poverty line used, the speed and scale of China’s poverty reduction is historically unprecedented. Over the past 40 years, the number of people in China with incomes below US$1.90 per day—the international poverty line as defined by the World Bank to track global extreme poverty—has fallen by close to 800 million, accounting for almost three-quarters of the global reduction in extreme poverty. In 2021, China declared that it had eradicated extreme poverty according to its national poverty threshold, and that it had built a “moderately prosperous society in all respects.” However, a significant number of people remain vulnerable, with incomes below a threshold more typically used to define poverty in upper-middle-income countries. China has set a new goal of approaching common prosperity by 2035, which can help keep the policy focus on the vulnerable population.
Four Decades of Poverty Reduction in China: Drivers, Insights for the World, and the Way Ahead explores the key drivers of China’s poverty alleviation achievements and considers the lessons of China’s experience for other developing countries. The report also makes suggestions for China’s future policies. China’s approach to poverty reduction was based on two pillars. The first aimed for broad-based economic transformation to open new economic opportunities and raise average incomes. The second was the recognition that targeted support was needed to alleviate persistent poverty; this support was initially provided to disadvantaged areas and later to individual households. The success of China’s economic development and the associated reduction of poverty also benefited from effective governance, which helped coordinate multiple government agencies and induce cooperation from nongovernment stakeholders. To illustrate the role of broad-based economic transformation for poverty alleviation, separate sections of the report analyze growing agricultural productivity, incremental industrialization, managed urbanization and rural-to-urban migration, and the role of infrastructure.
eBook