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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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    A comprehensive survey of the aldehyde dehydrogenase gene superfamily in Saccharum and the role of ScALDH2B-1 in the stress response

    Zang, ShoujianZou, WenhuiSu, YachunYou, Chuihuai...
    17页
    查看更多>>摘要：Aldehyde dehydrogenases (ALDHs) belong to NAD(P)+-dependent enzymes and are considered "aldehyde scavengers". They play crucial roles in growth, development, and environmental stress adaptation in plants. In this study, a total of 70 SsALDH and 14 ShALDH superfamily genes were identified in Saccharum spontaneum and Saccharum spp. R570 cultivar, respectively. Results showed that the SsALDH superfamily was classified into 10 ALDH families, and the ShALDH superfamily was divided into eight ALDH families. A co-expression network analysis suggested that these ALDH proteins may play vital roles in the stress response due to the fact that they are involved in the metabolism of proline, gamma-aminobutyrate, and lysine. The promotor cis -element prediction revealed that the ALDH genes may be regulated by many phytohormones and are involved in various stress responses. RNA-seq data and qRT-PCR analysis inferred that ALDH genes in Saccharum played various roles in response to drought, cold and Sporisorium scitamineum stresses, and they were constitutively expressed in different sugarcane tissues. Additionally, an expression analysis of ScALDH2B-1 suggested significant changes under various stresses. The prokaryotic expression of ScALDH2B-1 in Escherichia coli BL21 cells resulted in enhanced tolerance to salinity. The ectopic expression of ScALDH2B-1 in Nicotiana benthamiana showed that, after challenged by Fusarium solani var. coeruleum, several HR maker genes were upregulated, while the accumulation of H2O2 and HR-like cell death were triggered. A working model of the function of ALDHs in the Saccharum species was thus proposed. This study contributes to our understanding of the evolution and function of ALDH superfamily genes in Saccharum, and it also provides a baseline for the function identification of ScALDH2B-1 under biotic stress.
      原文链接:
    • NSTL
    • Elsevier

    Revisiting the mechanisms of arsenic uptake, transport and detoxification in plants

    Kumar, AlokBasu, SahanaRishu, Aniket KumarKumar, Gautam...
    15页
    查看更多>>摘要：Arsenic (As) contamination leading to toxicity in animals and humans has become a major concern in the last few decades. Chronic exposure to As occurs either through contaminated drinking water or food chain. Introduction of As in the food chain takes place by its excessive uptake from soil by plants due to the irrigation with As contaminated water. The major source of human exposure to As is through consumption of As-accumulating crops and vegetables. Arsenic taken up by the plants is translocated and accumulated in the edible plant parts making it a serious worldwide concern to take necessary steps. Developing plants with reduced As levels in their edible parts is the most plausible strategy for decreasing human As intake, which requires understanding the mechanism of As uptake from soil and its transport to the above ground tissues of plants. The present review sums up the recent progress made in understanding the As uptake, translocation and detoxification mechanisms in plants, underlining the role of transporters involved in these processes. Therefore, the expressions of the candidate genes for As uptake, translocation and detoxification has been analyzed under different developmental stages and tissues of model plant rice from publicly available microarray data. The review also summarized the biotechnological approaches for manipulation of As uptake, transport and tolerance associated genes to enhance As tolerance in different plant species. Overall, the review provides a comprehensive understanding of the potential strategies for lower As accumulation in plants to eliminate the As toxicity in human.
      原文链接:
    • NSTL
    • Elsevier

    Epicotyl morphophysiological dormancy in seeds of Paeonia ostii (Paeoniaceae): Seasonal temperature regulation of germination phenology

    Zhang, KeliangPan, HaoleiBaskin, Carol C.Baskin, Jerry M....
    10页
    查看更多>>摘要：Paeonia is one of the most popular ornamental plants in temperate regions, and its seeds have epicotyl dormancy. Our primary aim was to determine the sequence of temperatures required for radicle and shoot emergence in seeds of P. ostii and how these two distinct stages of dormancy-break are correlated with natural seasonal temperature changes. We tested the effects of various temperature regimes and sequences of regimes on growth of the underdeveloped embryo inside the seed, radicle emergence and shoot growth in the laboratory and germination responses to temperature under natural temperatures in an experimental garden and analyzed ABA and GA concentrations during the dormancy-breaking process. Prior to radical emergence, embryo length increased c. 330%. Embryo elongation and radicle emergence occurred in early October following seed dispersal in summer. The epicotyl-plumule did not differentiate until after embryo growth was completed and the radicle had emerged. Cold stratification was required to break epicotyl dormancy; consequently, shoot emergence did not occur until February when the temperature began to increase. Thus, seed dormancy break in P. ostii is phenologically well adapted to the seasonal cycle of the temperate zone. ABA and GA analyses suggest that root dormancy might be due to high ABA content and shoot dormancy to low GA content.
      原文链接:
    • NSTL
    • Elsevier

    Biofertilization with photosynthetic bacteria as a new strategy for mitigating photosynthetic acclimation to elevated CO2 on cherry tomato

    Du, BinShukla, M. K.Ding, RishengDu, Taisheng...
    13页
    查看更多>>摘要：The stimulated effects of elevated CO2 concentration decline over time in many C3 plants. However, the phenomenon is a rare occurrence on plants hosting some symbiosis bacteria. The photosynthesis acclimation associated with an extended period of high CO2 concentration was therefore studied in cherry tomato that treated with a kind of photosynthetic bacteria. Bio-fertilization with photosynthetic bacteria, which can fix nitrogen for host crops and contains a variety of growth promoting factors, can play an important role in maintaining photosynthetic activity. In this research, we conducted a CO2 elevation experiment combined different water regimes and inoculation with photosynthetic bacterium, to evaluate the improvement of photosynthesis acclimation by using photosynthesis bacteria, and to explore associated mechanisms for artificial chamber grown cherry tomatoes. As a result of these experiments, we found that elevated CO2 had a positive effect on cherry tomato photosynthetic activity and yield of all treatment. After 55 days of CO2 injection, photosynthetic acclimation was found in the plant of uninoculated photosynthetic bacteria, which were most pronounced in high water treatments. Reduced irrigation amounts decreased the magnitude of photosynthetic acclimation, but relative fruit yield gradually decreased after achieving a maximum. In contrast, the photosynthetic bacteria inoculated plants just showed a slightly down-regulation of photosynthesis under durative high CO2 condition. Because inoculation of photosynthetic bacteria increased the photosynthetic pigment content, mesophyll conductance, maximum carboxylation rate and maximum electron transport rate. Furthermore, inoculation with the photosynthetic bacteria diminished the yield penalties caused by the reduced irrigation treatment through promoting nitrogen content and relieve starch accumulation in tomato leaves compared to those of the uninoculated control. And enhanced yield of inoculated plants grown under durative high CO2 concentration were observed. The results suggest that photosynthesis bacteria application could be a potential means to further improve the CO2 stimulation effect on cherry tomato production.
      原文链接:
    • NSTL
    • Elsevier

    Receptor-like cytoplasmic kinase OsRLCK241 functions as an important regulator of abscisic acid synthesis and response in rice

    Wang, KeLi, ShenTian, HaoranChen, Cong...
    11页
    查看更多>>摘要：As an important receptor-like kinase subfamily in plants, receptor-like cytoplasmic kinases (RLCKs), such as Oryza sativa L. (Os) RLCK241, are critical in the response to abiotic stress conditions. However, the involvement of OsRLCK241 in the abscisic acid (ABA) signal response remains unknown. In this study, we found that OsRLCK241 participates in the ABA response in rice. The results showed that OsRLCK241 transcription was notably induced by ABA in the rice shoot and root in time-and dose-dependent manners. Additionally, beta-glucuronidase staining and analysis of subcellular localization demonstrated that OsRLCK241 directly responded to both ABA and salt treatments. Moreover, phenotypic and physiological analyses showed that OsRLCK241 overexpression decreased ABA sensitivity and ABA content relative to the wild-type variant (Kitaake) under salt stress, and OsRLCK241 loss-of-function variants consistently displayed the opposite ABA sensitivity phenotype and effects on ABA content. Furthermore, OsRLCK241 overexpression or loss of function modified stomatal patterning under salt stress. Quantitative real-time PCR indicated that the expression of most ABA synthesis-related marker genes, as well as that of genes involved in ABA signal transduction, was altered in both OsRLCK241-overexpressing rice lines and loss-of-function mutants under salt stress. These results suggest that OsRLCK241 is an important regulator of ABA synthesis and response in rice and expand the understanding of plant RLCKs.
      原文链接:
    • NSTL
    • Elsevier

    The ABA receptor gene MdPYL9 confers tolerance to drought stress in transgenic apple (Malus domestica)

    Yang, JieWang, MinZhou, ShashaXu, Bingyao...
    13页
    查看更多>>摘要：Abscisic acid (ABA) is an important phytohormone for plant growth, development, and the response to various types of abiotic stress. Pyrabactin Resistance 1 (PYR1)/PYR1-Like (PYL)/Regulatory Component of ABA Receptor (RCAR) family proteins (PYLs) are ABA receptors that have been studied in many plant species. However, no detailed functional studies of these genes in regulating apple drought tolerance have been reported. Here, we isolated a homolog of the ABA receptor PYL9 in Arabidopsis, MdPYL9, from apple (Malus domestica) and analyzed its role in regulating drought tolerance in transgenic apple plants. Gene structure and protein sequence analysis showed that MdPYL9 shares a high similarity with AtPYL9. Protein sequence comparison and 3D structure prediction identified several conserved motifs and residues that are important for ABA binding in MdPYL9, including the helix-grip structure and the gate and latch loops. Expression analysis showed that MdPYL9 was significantly induced by drought treatment. Overexpression of MdPYL9 conferred enhanced tolerance to drought stress in transgenic apple plants, including a higher photosynthetic rate and relative water content and lower MDA content and electrolyte leakage compared with wild-type plants. Lower accumulation of reactive oxygen species (ROS) and higher activity of antioxidant enzymes suggest that MdPYL9 overexpression could promote ROS scavenging and thus reduce oxidative damage in transgenic apple plants under drought stress. Yeast two-hybrid assays indicated that there were both ABA-dependent and ABA-independent interactions between MdPYL9 and the clade A subgroup members of the PP2C family (PP2CAs) in apple. Expression analysis identifed two PP2CA genes, MdHAI1 and MdHAI2, that were highly expressed under drought treatment by not expressed under normal conditions. These results provide new insight that could be used to aid future studies examining the function of MdPYLs and the mechanism by which they regulate apple drought tolerance.
      原文链接:
    • NSTL
    • Elsevier

    Structural responses of differentially adapted Cenchrus setigerus Vahl ecotypes to water deficit

    Sarwar, YasminAsghar, AnsaHameed, MansoorFatima, Sana...
    11页
    查看更多>>摘要：Two ecotypes of Cenchrus setigerus Vahl (birdwood grass) were collected from dry mountains surrounding hyper-saline Kalar Kahar Lake and Gatwala artificial forest plantation. The ramets of the two ecotypes were established in pots for 15 days and then subjected to 100% FC (control) or 75% and 50% FC (field capacity) levels. Growth attributes such as plant height, tillers per plant, leaves per plant, shoot fresh and dry weights were severely affected while root length was the only attribute that increased in both ecotypes under moisture stress. Root anatomical attributes like cortical and pith parenchyma, and vascular region thickness increased in both ecotypes under water stress. Root radius increased in the Faisalabad ecotype at 75% FC, while increased in Salt Range ecotype only at 50% FC. Stem cellular region, sclerenchymatous cell area, vascular bundle area and metaxylem area increased significantly under moderate and severe water deficit only in the Faisalabad ecotype. The Salt Range ecotype exhibited intensive sclerification and large vascular tissue at 50% FC. Leaf anatomical attributes like epidermal cell area, bundle sheath thickness, sclerenchyma thickness and its cell area, and, vascular bundles area significantly increased in the Salt Range ecotype with increasing water deficit. The Faisalabad ecotype showed significant increase in vascular bundle area, metaxylem area and adaxial stomatal area. These findings indicated that both C. setigerus ecotypes mainly relied on water conservation and survival rather than main-taining growth and biomass production. The anatomical modifications at root, stem and leaf levels ensured survival of C. setigerus ecotypes in extreme arid conditions.
      原文链接:
    • NSTL
    • Elsevier

    Do trait responses to simulated browsing in Quercus robur saplings affect their attractiveness to Capreolus capreolus the following year?

    Barrere, JulienCollet, CatherineSaid, SoniaBastianelli, Denis...
    10页
    查看更多>>摘要：With the rise of large herbivore populations in most northern hemisphere forests, browsing is becoming an increasingly important driver of forest regeneration dynamics. Among other processes affecting the regeneration, the concept of plant-herbivore feedback loops holds that browsed saplings are more subject to subsequent herbivory. This phenomenon is interpreted as a consequence of compensatory growth following browsing since fast growth is generally associated with higher digestibility and lower defense against herbivores. However, studies linking browsing-induced trait variations to subsequent attractiveness to herbivores are still lacking, especially in the forest context. In this study, we experimentally examine the existence of a feedback loop between oak (Quercus robur L.) and roe deer (Capreolus capreolus) and investigate its underlying morphological and chemical traits. We simulated single and repeated roe deer browsing on nursery-grown oak saplings and measured the changes in sapling height growth, lateral branching, leaf traits and winter shoot traits over two years. We conducted winter feeding trials with tame roe deer one year after the first treatment to test the effect of simulated browsing on sapling attractiveness. Simulated browsing reduced sapling height growth but had no effect on branching. Simulated browsing had no effect on leaf traits after half a year, but decreased the phenolic content and increased the fiber content of winter shoots the following winter. Contrary to our predictions, roe deer preferentially browsed control saplings over saplings previously browsed. After two years, repeated browsing promoted fast carbon acquisition leaf traits (high chlorophyll, high specific leaf area and low fiber content), reduced leaf phenolic content and increased leaf digestibility. We showed that a reduction in 1-year-old oak sapling height growth following browsing, combined with increased structural defense at the expense of chemical defense in winter shoots the following winter, was correlated with reduced browsing pressure, thereby challenging the feedback loop hypothesis. However, we also demonstrated that repeated browsing promoted fast carbon acquisition leaf traits in 2.5-year-old saplings, which tend to support the existence of a feedback loop on older and more intensively browsed saplings. As such, our study provides empirical evidence that morphological and physiological trait responses to browsing influence oak sapling attractiveness, but that the direction and magnitude of this effect depend on the ontogenic stage of the sapling and on the number of browsing events.
      原文链接:
    • NSTL
    • Elsevier

    ScMT10, a metallothionein-like gene from sugarcane, enhances freezing tolerance in Nicotiana tabacum transgenic plants

    Feng, MeichangYu, QingChen, YunFu, Zhiwei...
    13页
    查看更多>>摘要：Sugarcane (Saccharum spp. hybrid) is of tropical origin, yet generally cultivated in subtropical areas. Cold stress is a major environmental factor that impairs the production of sugarcane in that area. Metallothioneins, a family of small, cysteine-rich proteins, are proved to be involved in metal homeostasis and detoxification and thus alleviate stress-induced ROS accumulation. Here, a cDNA clone deducing a single Cys-rich domain type 2 metallothionein-like protein, designated ScMT10, was isolated from sugarcane. The level of ScMT10 expression was up-regulated by salicylic acid (SA), cold, and oxidative stress (H2O2) in sugarcane seedlings, but it was down-regulated in response to abscisic acid (ABA), methyl jasmonate (MeJA), heavy metal ions (Cu2+, Cd2+), and salinity. Transgenic tobacco (Nicotiana tabacum) plants (ScMT10-OE) showed a remarkable enhancement in freezing tolerance compared with wild-type plants (WT). Furthermore, ScMT10-OE tobacco showed a lower electrolyte leakage, reduced malondialdehyde contents, and slower ROS (including H2O2) accumulation under freezing stress and retained higher proline, soluble sugar, and relative chlorophyll content compared to WT plants. The expression profiles of ScMT10 in the transgenic tobacco were similar to those in sugarcane seedlings under different stresses. Besides, the level of H2O2 in the ScMT10-OE plants was comparable to that observed in WT plants under heavy metal, salt, and drought stress. Therefore, the transgenic plants did not perform better than WT plants under those stresses. Taken together, we present a hypothesis that ScMT10 was exclusively and positively involved in the cold stress-induced accumulation of reactive oxygen species (ROS). The overexpression of ScMT10 in tobacco decreased the contents of endogenous ROS, MDA, and relative electric conductivity. It increased the accumulation of proline, soluble sugar, and relative chlorophyll under freezing stress, which alleviated the oxidative damage to the cell membrane during freezing exposure. ScMT10 can be considered as a candidate gene for cold-tolerance trait improvement.
      原文链接:
    • NSTL
    • Elsevier

    Photomorphogenesis in plants: The central role of phytochrome interacting factors (PIFs)

    Wang, PeilinAbid, Muhammad AliQanmber, GhulamAskari, Muhammad...
    12页
    查看更多>>摘要：Light is the primary source of energy that powers photosynthesis and growth in plants. A wide range of signals and information for morphogenesis and many other physiological processes are triggered by light. A small group of basic helix-loop-helix domain-containing transcription factors known as phytochrome-interacting factors (PIFs) repress seed germination, regulate seedling skotomorphogenesis, and promote several developmental changes by regulating over one thousand genes. In the dark, Arabidopsis seedlings undergo skotomorphogenesis, which is a developmental strategy that seedlings use after germination to accelerate their growth in soil and optimize the plant shape before reaching the light. Light-activated phytochromes (PHYA and PHYB) bind directly to these PIF proteins which are then phosphorylated, followed by their rapid degradation and the reversal of their activities. This precise control of photomorphogenesis has been the subject of intensive investigation. In the past decade, several studies have highlighted the complex mechanism of how PIFs are regulated to fine-tune photomorphogenesis. Here, we review recent advances in this signaling pathway and present emerging evidence showing that other molecular pathways also converge to regulate PIF activity, including abiotic stress and hormonal signaling pathways. We also summarize past studies conducted on the role of PIFs in crop improvement. The roles of light-induced signaling networks and the associated molecular mechanisms have been significantly neglected in crop plants. These advances will almost certainly fuel future research on light signaling transcription factors in other crop plants for stress tolerance studies. Such information also enables breeders and plant biologists to improve crop yield and develop climate-tolerant crops that can adapt to constantly changing environmental conditions.
      原文链接:
    • NSTL
    • Elsevier