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Environmental and experimental botany
Pergamon Press,
Environmental and experimental botany

Pergamon Press,

0098-8472

Environmental and experimental botany/Journal Environmental and experimental botanySCIISTP
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    Leaf anatomy, photosynthesis, and chloroplast ultrastructure of Heptacodium miconioides seedlings reveal adaptation to light environment

    Zhang, YanfeiChen, ChaoJin, ZexinYang, Zhongnan...
    11页
    查看更多>>摘要：Light intensity is a critical factor for the plant survival and early growth. Heptacodium miconioides, a well accepted ornamental plant, has been endangered due to fragmented habitats in the wild. To better understand the light adaptation mechanisms of H. miconioides, we investigated the morphology, photosynthesis, chloroplast ultrastructure, and chloroplast gene expression of the leaves under high light (HL), moderate light (ML), and low light (LL) conditions. With decreasing light intensity, the specific leaf area and chlorophyll contents of H. miconioides increased, whereas the leaf size first increased followed by a decrease. The maximum net photosynthetic rate under ML and HL treatments were significantly higher than that under LL treatment. However, leaves under ML treatment exhibited the lower dark respiration rate and light compensation point than those under HL treatment. The leaf thickness, palisade tissue, spongy tissue, and stomatal density were obviously reduced with decreasing light intensity. Chloroplast ultrastructure showed the better development in leaves under ML condition, and the size of chloroplast, the number of starch grains and plastoglobules increased significantly. In addition, the expression levels of genes involved in chlorophyll biosynthesis (HEMA, CLH, CHLI, CHLH, CHLG) were higher under ML than LL treatment, but lower under HL treatment. The up-regulation of the photosystem II (PsbB, PsbD, PsbO) genes expression play an important role in under ML and LL treatments. Taken together, we proposed that the optimal growth of H. miconioides seedlings varies between HL and ML but had poor growth under LL condition. The improvement in H. miconioides growth under moderate shade was mainly through its effects on leaf morphology, chloroplast development, and light capture efficiency of PSII phase.
      原文链接:
    • NSTL
    • Elsevier

    Reducing vapor pressure deficit improves calcium absorption by optimizing plant structure, stomatal morphology, and aquaporins in tomatoes

    Yu, XuemeiZhao, MingfeiWang, XiaoyanJiao, Xiaocong...
    13页
    查看更多>>摘要：High temperatures and arid air environments hinder calcium absorption in tomatoes (Solanum lycopersicum L.), decreasing the yield significantly. Changing atmospheric vapor pressure deficit (VPD) is an important measure to improve the passive water movement that pulls water and calcium out of the soil. However, it remains unclear how the changes in plant structure, stomatal morphology, plasma membrane intrinsic proteins (PIPs), and tonoplast intrinsic proteins (TIPs) drive calcium absorption and water transport under different VPDs. This study examined the role of plant structure, stomatal morphology, TIPs, and PIPs on the calcium absorption of two tomato cultivars (Jinpeng and Zhongza) to long-term growth under high and appropriate VPDs, besides analyzing the correlation between the indicators. The results showed that major vein density, net assimilation rate, and stomatal conductance were the main reasons hindering the leaf calcium absorption, while fruit calcium absorption had the highest correlation with palisade tissue thickness. Reducing the VPD reduced the water potential gradient at the leaf-air boundary, increased the cross-sectional area of the xylem duct in stems and roots, and increased the leaf vein density in the plant. Meanwhile, a reduced VPD increased net assimilation rate, stomatal conductance and size, and decreased the spongy tissue thickness. Over the long-term, calcium absorption in leaves and fruits, calcium accumulation in fruit peels, yield, and yield water use efficiency was greatly increased for the two tomato cultivars. Additionally, most SlTIPs and SlPIPs were significantly upregulated in both cultivars under a high VPD. These results suggest that plant structure, stomatal morphology, TIPs and PIPs efficiently regulate calcium absorption and water transport under different VPDs.
      原文链接:
    • NSTL
    • Elsevier

    Role of nodes in accumulation and distribution of cadmium and its relationship with nutrient distribution and photosynthesis in the growth and regrowth of Brachiaria decumbens

    dos Santos, Felipe HipolitoColzato, MarinaMontanha, Gabriel SgarbieroNakamura, Luiz Ricardo...
    14页
    查看更多>>摘要：Nodes play an important role in the accumulation and distribution of cadmium (Cd) in graminaceous-like rice (Oryza sativa L.), but what about grasses used for Cd phytoextraction? In this study we evaluated i) if possible Cd accumulation in the basal node compromises the growth of Brachiaria decumbens; ii) the role of nodes in Cd and nutrient accumulation and distribution in leaves; and iii) the relationship between Cd-induced nutritional disorders and photosynthetic impairment. B. decumbens cv. Basilisk was grown for two periods in an Oxisol presenting 0.02 (control), 2.28, 5.17 and 11.23 mg kg-1 soil with bioavailable Cd. The tillering of B. decumbens was not compromised, despite the basal node presenting high Cd concentrations, although Cd did induce stem shortening, especially in the regrowth period. Nodes restricted Cd upward transportation in the initial growth period, but Cd reached the upper nodes in the regrowth period. This result did not affect nutrient distribution into the aerial tissues of the grass. However, nutritional disorders induced by Cd appeared in the lower plant parts (especially in the growth period) due to Cd absorption by the basal node. The only effect of Cd-induced impairment on photosynthesis of B. decumbens was a reduction in instantaneous and intrinsic water use efficiency in leaf III (older), which presented higher Cd concentrations than leaves I and II (newer). In addition to the Cd effect, photosynthetic activity decreased in the regrowth period, probably in response to the lower ambient temperature in this period compared to the growth period. The nodes of B. decumbens keep Cd accumulated in the lower plant parts and avoid nutritional disorders and photosynthesis impairment in the plant leaves allowing for growth and biomass yield.
      原文链接:
    • NSTL
    • Elsevier

    How do native grasses from South America handle zinc excess in the soil? A physiological approach

    Moura-Bueno, Jean MichelDrescher, Gerson LaersonMarques, Anderson Cesar RamosKulmann, Matheus Severo de Souza...
    10页
    查看更多>>摘要：The excess of zinc (Zn) in vineyard soils promotes grape yield restraints. Thus, it is urgent to set up sustainable strategies aiming at decrease phytotoxic potential of Zn for crops. The selection on biochemical and physiological bases of wild plants to intercrop with perennial ones might be the key step to identify and characterize unknown mechanisms of metal tolerance in these plant species. This study aimed to evaluate the physiological and biochemical responses of native grasses of South America exposed to high Zn concentrations in the soil. The soil was sampled in a non-anthropized area and it was incubated with the following Zn amounts: 0, 30, 60, 120, or 180 mg Zn kg-1 soil. The native grass species considered were: Axonopus affi nis, Paspalum notatum, and Paspalum plicatulum. Dry mass accumulation, the nutritional composition of plants, photosynthetic parameters, antioxidant enzyme activities, and oxidative stress indicators have been evaluated. A. affinis specie increased photosynthetic rate, pigments concentrations, and biomass production as Zn increased in soil. While it did not enhance the reactive oxygen species, and did not show lipid peroxidation under Zn excess. On the other hand, species P. plicatulum and P. notatum were more sensitive to Zn excess in the soil, showing oxidative injuries, which reduced plant growth. Hence, results show that A. affinis possess the physiological and biochemical features for controlling the Zn availability in the soil supporting, thus, the idea of its effective use in agronomical strategies for containing the Zn toxicity problem.
      原文链接:
    • NSTL
    • Elsevier

    The high chlorophyll fluorescence 244 (HCF244) Is potentially involved in glutathione peroxidase 7-regulated high light stress in Arabidopsis thaliana

    Li, KunJia, QianyunGuo, JinggongZhu, Zhijuan...
    12页
    查看更多>>摘要：Glutathione peroxidases (GPXs) are key enzymes of the antioxidant network in plants. In this study, we show that mutations in the Arabidopsis thaliana GPX7 gene result in increased photo-bleaching under high light (HL) condition compared to wild type (WT) plants. Moreover, GPX7 possesses peroxidase activity and GPX7-deficient mutants are hypersensitive to hydrogen peroxide. GPX7 protein is located in the chloroplast stroma and thylakoid membrane and GPX7 expression is strongly induced by HL. Yeast two-hybrid screening identified a member of the atypical short-chain dehydrogenase/reductase superfamily, high chlorophyll fluorescence phenotype 244 (HCF244), a protein involved in photosystem II biogenesis, as a putative GPX7 interactor. Moreover, the photosynthetic efficiency and the accumulation of HCF244 and D1 proteins, the key component of photosystem II reaction center, are decreased in gpx7-1 comparing with WT plants under HL treatment. These results suggest that HCF244 might play roles in GPX7-mediated HL-induced photo-oxidation repair system.
      原文链接:
    • NSTL
    • Elsevier

    Interplay of ZnONPs and/or SeNPs induces arsenic tolerance in soybean by regulation of antioxidants pool, WRKY genes, and expression of arsenic transporters

    Zeeshan, MuhammadHu, Yu XinAfridi, Muhammad SiddiqueAhmad, Bushra...
    12页
    查看更多>>摘要：Arsenic is a nonessential element that confers toxicity to plants. Excessive arsenic accumulation in food crops poses safety concerns for human and animal health. To date, our understanding of the alleviation mechanism of As(V) toxicity in soybean plant employing NP is less known. Thus, the objective of the present study was to evaluate the effectiveness of zinc oxid nanoparticle (ZnONP) and/or selenium nanoparticle (SeNP) treatment on arsenic stress in seedling of soybean (Glycine max [L] Merrill). Soybean seedlings were grown hydroponically in 10 liters pots, treated at V2 growth stage with arsenate (25 mu M L-1), two concentrations of ZnONPs (25 mu M and 50 mu M L-1) and two concentrations of elemental SeNPs (10 mu M and 25 mu M L-1) separately and in tandem, and then kept for further 10 d. Positive control (T2) significantly induced electrolyte leakage (EL) and facilitated the accumulation of O-2(-) and H2O2 in roots and leaf tissues, along with higher deposition of As in sensitive cell organs including cellular organelles and cell wall. The application of ZnONPs and SeNPs, both independently and in tandem, promoted the As compartmentalization into vacuole, reduced the EL and rescued plant health by enhanced the metal tolerance index (MTI). In addition, cellular toxicants (i.e., O-2(-), H2O2 and GSSG) were drastically reduced because of the steady increased in MDHAR, GSTs, GSH and PCs levels in response to the nanoparticles treatment than in positive control (T2). Moreover, Na+ K+-ATPase and Ca++ Mg++-ATPase activities were also induced in response to NPs treatment groups. All the nanoparticles treatment groups displayed elevated expression of TFs (GmWRKY6, GmWRKY46, GmWRKY56, and GmWRKY106) particularly under 50 mu M L-1 ZnONPs + 10 mu M L-1 SeNPs (T8) compared to both negative (T1) and positive control (T2). More importantly, application of nanoparticles, both either independently or in tandem, decreased the expression of GmPT1, GmPT2, GmPT3, GmPT4 and GmPT8 with an exception of GmPT2 under SeNPs treatment group. Thus, the concurrent application of ZnONPs + SeNPs can be considered as eco-friendly fertilizer that will mimic As(V) toxicity and improve the growth and yield of soybean plants in As polluted areas.
      原文链接:
    • NSTL
    • Elsevier

    Metal tolerance protein family members are involved in Mn homeostasis through internal compartmentation and exocytosis in Brassica napus

    Gu, DongfangZhou, XueliYin, XinghuaWu, Mengyao...
    13页
    查看更多>>摘要：Mineral elements, including manganese (Mn), are indispensable for plant growth and development. However, plants cultivated on acidic soils are vulnerable to Mn2+ toxicity due to a prevalently phytotoxic level of Mn2+. Metal tolerance proteins (MTPs) were demonstrated to be essential for metal homeostasis and tolerance in different plant species. In this study, we present the functional characteristics of BnMTP8 and BnMTP9 from Brassica napus. The expression level of BnMTP8 was most prominent in rapeseed roots and was only markedly up regulated in shoots by excess Mn2+. In contrast, BnMTP9 was most abundant in shoots. Expression of BnMTP8 and BnMTP9 in Saccharomyces cerevisiae compensated the Mn2+-hypersensitivity of Delta pmr1 by increasing metal sequestration and efflux, respectively. In addition, heteroexpression of BnMTP8 restored Mn2+ tolerance of Arabidopsis mtp8 mutants and increased Mn2+ accumulation in tissues and leaf vacuoles. Expression of BnMTP9 in Arabidopsis mtp11 mutants restored their growth and reduced Mn2+ concentrations in mesophyll protoplasts and tissues upon elevated levels of Mn2+. Transient expression of GFP-fusion constructs in protoplasts showed that BnMTP8 and BnMTP9 localize to pre-vacuolar compartments and the trans-Golgi network, respectively. However, high extracellular Mn2+ in Arabidopsis root cells triggered BnMTP8-GFP relocation to the tonoplast and BnMTP9-GFP relocation to the plasma membrane, suggesting that these two proteins are involved in vacuolar Mn2+ sequestration and cytosolic Mn2+ export, respectively. Taken together, these findings indicate that BnMTP8 and BnMTP9 load Mn2+ into vesicles for subsequent delivery to the vacuole or secretion into extracellular spaces, respectively, thereby cooperating to maintain Mn2+ homeostasis in the roots and shoots of rapeseed.
      原文链接:
    • NSTL
    • Elsevier

    Plant hormones coordinate monolignol biosynthesis with seasonal changes in Populus tomentosa

    Chao, NanChen, Wei-QiCao, XuJiang, Xiang-Ning...
    11页
    查看更多>>摘要：Temperate woody plants suffer environmental stresses caused by seasonal changes. Seasonal changes affect tree cambium activity, resulting in the annual periodicity of growth. In the present study, we provide a model for plant hormone coordination of monolignol biosynthesis to cope with the seasonal changes in a poplar species. First, 27 core lignin-related genes were identified in Populus tomentosa, and co-expression in lignifying tissues was identified. Combining spatial and seasonal expression analysis and the seasonal dynamic changes in plant hormones of Populus tomentosa, we found that poplars reorganized plant hormone (cytokinin;3-indoleacetic acid, IAA; and abscisic acid, ABA) biosynthesis and transport pathways with a winter-down pattern, resulting in decreases of cytokinin, IAA, and ABA content in cambium cells. The same expression pattern was also found for lignin-related genes involved in monolignol precursors biosynthesis. The monolignol specific pathway genes PtoCAD1, 2, 8, PtoCCR1, 7 and PtoF5H2 showed contrasting winter-up expression patterns. We propose that 1) plant hormones, such as cytokinin, IAA, and ABA regulate the cambium activity and coordinate monolignol biosynthesis, especially the components upstream of this pathway, with seasonal changes in Populus tomentosa; 2) the inhibition of the biosynthesis of hydroxycinnamoyl-CoA esters and the accumulation of monolignol in winter are responsible for surviving the cold winter and provide materials for fast growth during the following spring.
      原文链接:
    • NSTL
    • Elsevier

    Genome-wide expression and variation in nucleotide sequences lead to differential response of Arabidopsis thaliana ecotypes towards arsenic stress under sulfur limiting condition

    Khare, RiaV. Dhar, YogeshwarSandhu, GurpreetSingh, Shikha...
    13页
    查看更多>>摘要：Abiotic stresses such as heavy metals and nutrient imbalance constitute a significant threat to plant productivity. Among the known heavy metals, arsenic (As) toxicity widely affects plants and animals. In the recent past, various approaches have been used to study and ameliorate As accumulation in the plants. Of the different approaches, the detoxification mechanism utilizes various sulfur-related compounds; therefore, the limitation of sulfur leads to enhanced toxicity in plants. Though studies have suggested links between As and sulfur responses, a deeper understanding of the molecular mechanisms of these responses is required. In this study, transcriptome analysis of the Arabidopsis accessions (Koz2-2 and Ri-0) with contrasting responses to sulfate limitation and As stress was carried out to identify genes involved in regulating various processes. Several genes associated with growth and development, stress, or sulfate metabolism and secondary plant product biosynthesis were found to be differentially expressed in contrasting accessions under sulfate limitation and As stress. A set of genes, including DREB1A and Marneral Synthase 1(MRN1), were exclusively upregulated under the combined stress in Koz2-2. Further, transcriptome analysis also revealed higher nucleotide variation in Koz2-2 than in Ri-0, which could be a reason for the contrasting response under the different stresses among these accessions. Interestingly, LCR44 (Low molecular weight Cysteine Rich 44), a putative defensin-like protein 73, was found to be uniquely upregulated in Koz2-2. The sequence analysis of LCR44 through transcriptome datasets suggested intron retention and insertion of nucleotides in Koz2-2. Hence, this study enriches the knowledge of genetic components to cope with sulfate assimilation and As stress in plants.
      原文链接:
    • NSTL
    • Elsevier

    Grafting improves tolerance to combined drought and heat stresses by modifying metabolism in citrus scion

    Balfagon, DamianRambla, Jose L.Granell, AntonioArbona, Vicent...
    11页
    查看更多>>摘要：Mediterranean basin and other citrus-growing areas, such as Florida or California, are among the most vulnerable regions to the impacts of global warming. Therefore, citrus will be likely subjected to increasing periods of water scarcity combined with high temperatures that will impair plant growth, development and yield. In citrus industry, grafting is used to improve varietal characteristics, such as abiotic stress tolerance. Previous research showed that under drought and heat stress conditions, Carrizo citrange (Poncirus trifoliata x Citrus sinensis) is a better rootstock than Cleopatra mandarin (Citrus reshni) because it induces a higher antioxidant activity on the scion, reducing oxidative damage and increasing plant tolerance. Here, it is shown that metabolic reconfiguration, including changes in carbohydrate and amino acid fluxes, are key responses for plant acclimation to stress conditions. Moreover, the importance of the rootstock on scion metabolic and hormonal responses to drought and heat stress combination has been addressed by using reciprocal grafting between Carrizo and Cleopatra genotypes. Thus, Carrizo as a rootstock improves the metabolic and hormonal response of Cleopatra scions to the stress combination by inducing the accumulation of protective compounds such as raffinose, galactinol and salicylic acid. In turn, Cleopatra as a rootstock reduces levels of raffinose, galactinol, proline, phenylalanine and tryptophan in Carrizo scions, which impairs plant tolerance to the stress combination. Our findings show the effect of the rootstock on scion metabolic response to stress combination and remark the importance of the rootstock in citrus plants exposed to harsh environmental conditions.
      原文链接:
    • NSTL
    • Elsevier