Plants

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18 pages, 2667 KiB

Open AccessArticle

Plasticity of the Root System Architecture and Leaf Gas Exchange Parameters Are Important for Maintaining Bottle Gourd Responses under Water Deficit

by Dinoclaudio Zacarias Rafael, Osvin Arriagada, Guillermo Toro, Jacob Mashilo, Freddy Mora-Poblete and Rodrigo Iván Contreras-Soto

Plants 2020, 9(12), 1697; https://doi.org/10.3390/plants9121697 - 3 Dec 2020

Cited by 6 | Viewed by 2889

Abstract

The evaluation of root system architecture (RSA) development and the physiological responses of crop plants grown under water-limited conditions are of great importance. The purpose of this study was to examine the short-term variation of the morphological and physiological plasticity of Lagenaria siceraria [...] Read more.

The evaluation of root system architecture (RSA) development and the physiological responses of crop plants grown under water-limited conditions are of great importance. The purpose of this study was to examine the short-term variation of the morphological and physiological plasticity of Lagenaria siceraria genotypes under water deficit, evaluating the changes in the relationship between the root system architecture and leaf physiological responses. Bottle gourd genotypes were grown in rhizoboxes under well-watered and water deficit conditions. Significant genotype-water regime interactions were observed for several RSA traits and physiological parameters. Biplot analyses confirmed that the drought-tolerant genotypes (BG-48 and GC) showed a high net CO₂ assimilation rate, stomatal conductance, transpiration rates with a smaller length, and a reduced root length density of second-order lateral roots, whereas the genotypes BG-67 and Osorno were identified as drought-sensitive and showed greater values for average root length and the density of second-order lateral roots. Consequently, a reduced length and density of lateral roots in bottle gourd should constitute a response to water deficit. The root traits studied here can be used to evaluate bottle gourd performance under novel water management strategies and as criteria for breeding selection. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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24 pages, 3312 KiB

Open AccessFeature PaperArticle

Responses to Salt Stress in Portulaca: Insight into Its Tolerance Mechanisms

by Orsolya Borsai, Mohamad Al Hassan, Cornel Negrușier, M. Dolores Raigón, Monica Boscaiu, Radu E. Sestraș and Oscar Vicente

Plants 2020, 9(12), 1660; https://doi.org/10.3390/plants9121660 - 27 Nov 2020

Cited by 22 | Viewed by 3768

Abstract

Climate change and its detrimental effects on agricultural production, freshwater availability and biodiversity accentuated the need for more stress-tolerant varieties of crops. This requires unraveling the underlying pathways that convey tolerance to abiotic stress in wild relatives of food crops, industrial crops and [...] Read more.

Climate change and its detrimental effects on agricultural production, freshwater availability and biodiversity accentuated the need for more stress-tolerant varieties of crops. This requires unraveling the underlying pathways that convey tolerance to abiotic stress in wild relatives of food crops, industrial crops and ornamentals, whose tolerance was not eroded by crop cycles. In this work we try to demonstrate the feasibility of such strategy applying and investigating the effects of saline stress in different species and cultivars of Portulaca. We attempted to unravel the main mechanisms of stress tolerance in this genus and to identify genotypes with higher tolerance, a procedure that could be used as an early detection method for other ornamental and minor crops. To investigate these mechanisms, six-week-old seedlings were subjected to saline stress for 5 weeks with increasing salt concentrations (up to 400 mM NaCl). Several growth parameters and biochemical stress markers were determined in treated and control plants, such as photosynthetic pigments, monovalent ions (Na⁺, K⁺ and Cl⁻), different osmolytes (proline and soluble sugars), oxidative stress markers (malondialdehyde—a by-product of membrane lipid peroxidation—MDA) and non-enzymatic antioxidants (total phenolic compounds and total flavonoids). The applied salt stress inhibited plant growth, degraded photosynthetic pigments, increased concentrations of specific osmolytes in both leaves and roots, but did not induce significant oxidative stress, as demonstrated by only small fluctuations in MDA levels. All Portulaca genotypes analyzed were found to be Na⁺ and Cl⁻ includers, accumulating high amounts of these ions under saline stress conditions, but P. grandiflora proved to be more salt tolerant, showing only a small reduction under growth stress, an increased flower production and the lowest reduction in K⁺/Na⁺ rate in its leaves. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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13 pages, 757 KiB

Open AccessArticle

Responses of Upland Cotton (Gossypium hirsutum L.) Lines to Irrigated and Rainfed Conditions of Texas High Plains

by Addissu. G. Ayele, Jane K. Dever, Carol M. Kelly, Monica Sheehan, Valerie Morgan and Paxton Payton

Plants 2020, 9(11), 1598; https://doi.org/10.3390/plants9111598 - 18 Nov 2020

Cited by 6 | Viewed by 2452

Abstract

Understanding drought stress responses and the identification of phenotypic traits associated with drought are key factors in breeding for sustainable cotton production in limited irrigation water of semi-arid environments. The objective of this study was to evaluate the responses of upland cotton lines [...] Read more.

Understanding drought stress responses and the identification of phenotypic traits associated with drought are key factors in breeding for sustainable cotton production in limited irrigation water of semi-arid environments. The objective of this study was to evaluate the responses of upland cotton lines to rainfed and irrigated conditions. We compared selected agronomic traits over time, final yield and fiber quality of cotton lines grown in irrigated and rainfed trials. Under rainfed conditions, the average number of squares per plant sharply declined during weeks 10 to 14 while the average number of bolls per plant significantly reduced during weeks 13 to 15 after planting. Therefore, weeks 10 to 14 and weeks 13 to 15 are critical plant growth stages to differentiate among upland cotton lines for square and boll set, respectively, under drought stress. Variation in square and boll set during this stage may translate into variable lint percent, lint yield and fiber properties under water-limited conditions. Lint yield and fiber quality were markedly affected under rainfed conditions in all cotton lines tested. Despite significantly reduced lint yield in rainfed trials, some cotton lines including 11-21-703S, 06-46-153P, CS 50, L23, FM 989 and DP 491 performed relatively well under stress compared to other cotton lines. The results also reveal that cotton lines show variable responses for fiber properties under irrigated and rainfed trials. Breeding line 12-8-103S produced long, uniform and strong fibers under both irrigated and rainfed conditions. The significant variation observed among cotton genotypes for agronomic characteristics, yield and fiber quality under rainfed conditions indicate potential to breed cotton for improved drought tolerance. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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13 pages, 983 KiB

Open AccessArticle

The Influence of Soil Acidity on the Physiological Responses of Two Bread Wheat Cultivars

by Brigitta Tóth, Csaba Juhász, Maryke Labuschagne and Makoena Joyce Moloi

Plants 2020, 9(11), 1472; https://doi.org/10.3390/plants9111472 - 31 Oct 2020

Cited by 16 | Viewed by 4021

Abstract

The recent study was conducted to examine the influence of acidic soil on the activities of ascorbate (APX) and guaiacol peroxidase (POD), proline, protein as well as malon-dialdehyde (MDA) content, in two commercial spring wheat cultivars (PAN3497 and SST806) at different growth stages [...] Read more.

The recent study was conducted to examine the influence of acidic soil on the activities of ascorbate (APX) and guaiacol peroxidase (POD), proline, protein as well as malon-dialdehyde (MDA) content, in two commercial spring wheat cultivars (PAN3497 and SST806) at different growth stages (tillering and grain filling). A cultivar effect was significant only for MDA content, while the treatment effect was highly significant for proline, protein, and MDA. The sampling time effect was significant for most characteristics. MDA, antioxidative capacity, as well as protein content increased with maturity. At grain filling, MDA and proline contents were significantly higher at pH 5 than pH 6 and 7 for both cultivars, with the highest content in SST806. Similarly, SST806 had significantly higher APX and POD when growing at pH 5. There were no significant differences in protein content at grain filling between either genotype or treatments affected by low pH. This study showed that growth stage and soil pH influence the rate of lipid peroxidation as well as the antioxidative capacity of wheat, with a larger effect at grain filling, at pH 5. Although SST806 had higher proline, POD, and APX content than PAN3497 at this growth stage, this coincided with a very high MDA content. This shows that the high antioxidative capacity observed here, was not associated with a reduction of lipid peroxidation under low soil pH. Further research should, therefore, be done to establish the role of the induced antioxidant system in association with growth and yield in wheat. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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18 pages, 3820 KiB

Open AccessArticle

Insights into the Superoxide Dismutase Gene Family and Its Roles in Dendrobium catenatum under Abiotic Stresses

by Hui Huang, Hui Wang, Yan Tong and Yuhua Wang

Plants 2020, 9(11), 1452; https://doi.org/10.3390/plants9111452 - 28 Oct 2020

Cited by 12 | Viewed by 2434

Abstract

Dendrobium catenatum is a member of epiphytic orchids with extensive range of pharmacological properties and ornamental values. Superoxide dismutase (SOD), a key member of antioxidant system, plays a vital role in protecting plants against oxidative damage caused by various biotic and abiotic stresses. [...] Read more.

Dendrobium catenatum is a member of epiphytic orchids with extensive range of pharmacological properties and ornamental values. Superoxide dismutase (SOD), a key member of antioxidant system, plays a vital role in protecting plants against oxidative damage caused by various biotic and abiotic stresses. So far, little is known about the SOD gene family in D. catenatum. In this study, eight SOD genes, including four Cu/ZnSODs, three FeSODs and one MnSOD, were identified in D. catenatum genome. Phylogenetic analyses of SOD proteins in D. catenatum and several other species revealed that these SOD proteins can be assigned to three subfamilies based on their metal co-factors. Moreover, the similarities in conserved motifs and gene structures in the same subfamily corroborated their classification and inferred evolutionary relationships. There were many hormone and stress response elements in DcaSODs, of which light responsiveness elements was the largest group. All DcaSODs displayed tissue-specific expression patterns and exhibited abundant expression levels in flower and leaf. According to public RNA-seq data and qRT-PCR analysis showed that the almost DcaSODs, except for DcaFSD2, were highly expressed under cold and drought treatments. Under heat, light, and salt stresses, DcaCSD1, DcaCSD2, DcaCSD3 were always significantly up-regulated, which may play a vital role in coping with various stresses. The expression levels of DcaFSD1 and DcaFSD2 were promoted by high light, suggesting their important roles in light response. These findings provided valuable information for further research on DcaSODs in D. catenatum. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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20 pages, 2343 KiB

Open AccessArticle

Comparative Physiological and Proteomic Analysis Reveals Different Involvement of Proteins during Artificial Aging of Siberian Wildrye Seeds

by Xiong Lei, Wenhui Liu, Junming Zhao, Minghong You, Chaohui Xiong, Yi Xiong, Yanli Xiong, Qingqing Yu, Shiqie Bai and Xiao Ma

Plants 2020, 9(10), 1370; https://doi.org/10.3390/plants9101370 - 15 Oct 2020

Cited by 15 | Viewed by 2598

Abstract

Seed aging has an important effect on the germplasm preservation and industrialized production of Siberian wildrye (Elymus sibiricus) in the Qinghai-Tibet Plateau. However, so far its underlying molecular mechanisms still largely remain unknown. To shed light on this topic, one-year stored [...] Read more.

Seed aging has an important effect on the germplasm preservation and industrialized production of Siberian wildrye (Elymus sibiricus) in the Qinghai-Tibet Plateau. However, so far its underlying molecular mechanisms still largely remain unknown. To shed light on this topic, one-year stored seeds of E. sibiricus were exposed to artificial aging treatments (AAT), followed by seed vigor characteristics and physiological status monitoring. Then global proteomics analysis was undertaken by the tandem mass tags (TMT) technique, and the proteins were quantified with liquid chromatography-tandem mass spectrometry on three aging time points (0 h, 36 h and 72 h). Finally, we verified the expression of related proteins by parallel reaction monitoring (PRM). Our results demonstrated that the seed vigor decreased remarkably in response to artificial aging, but the relative ion-leakage and malondialdehyde content, superoxide anion and hydrogen peroxide showed the opposite situation. Proteomic results showed that a total of 4169 proteins were identified and quantified. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that a series of key pathways including carbohydrate metabolism, lipid metabolism, and antioxidant activity were severely damaged by aging treatments. Numerous key proteins such as glyceraldehyde triphosphate glyceraldehyde dehydrogenase, succinate dehydrogenase, lipoxygenase, peroxidase, glutathione-s-transferase and late embryogenesis abundant proteins were significantly down-regulated. However, the up-regulation of the heat shock protein family has made a positive contribution to oxidative stress resistance in seeds. This study provides a useful catalog of the E. sibiricus proteomes with insights into the future genetic improvement of seed storability. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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11 pages, 2300 KiB

Open AccessCommunication

Decomposition of Calcium Oxalate Crystals in Colobanthus quitensis under CO₂ Limiting Conditions

by Olman Gómez-Espinoza, Daniel González-Ramírez, Panagiota Bresta, George Karabourniotis and León A. Bravo

Plants 2020, 9(10), 1307; https://doi.org/10.3390/plants9101307 - 2 Oct 2020

Cited by 10 | Viewed by 7435

Abstract

Calcium oxalate (CaOx) crystals are widespread among plant species. Their functions are not yet completely understood; however, they can provide tolerance against multiple environmental stress factors. Recent evidence suggested that CaOx crystals function as carbon reservoirs since its decomposition provides CO₂ that [...] Read more.

Calcium oxalate (CaOx) crystals are widespread among plant species. Their functions are not yet completely understood; however, they can provide tolerance against multiple environmental stress factors. Recent evidence suggested that CaOx crystals function as carbon reservoirs since its decomposition provides CO₂ that may be used as carbon source for photosynthesis. This might be advantageous in plants with reduced mesophyll conductance, such as the Antarctic plant Colobanthus quitensis, which have shown CO₂ diffusion limitations. In this study, we evaluate the effect of two CO₂ concentrations in the CaOx crystals decomposition and chlorophyll fluorescence of C. quitensis. Plants were exposed to airflows with 400 ppm and 11.5 ppm CO₂ and the number and relative size of crystals, electron transport rate (ETR), and oxalate oxidase (OxO) activity were monitored along time (10 h). Here we showed that leaf crystal area decreases over time in plants with 11.5 ppm CO₂, which was accompanied by increased OxO activity and only a slight decrease in the ETR. These results suggested a relation between CO₂ limiting conditions and the CaOx crystals decomposition in C. quitensis. Hence, crystal decomposition could be a complementary endogenous mechanism for CO₂ supply in plants facing the Antarctic stressful habitat. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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16 pages, 3947 KiB

Open AccessArticle

Genome-Wide Identification of Barley ABC Genes and Their Expression in Response to Abiotic Stress Treatment

by Ziling Zhang, Tao Tong, Yunxia Fang, Junjun Zheng, Xian Zhang, Chunyu Niu, Jia Li, Xiaoqin Zhang and Dawei Xue

Plants 2020, 9(10), 1281; https://doi.org/10.3390/plants9101281 - 28 Sep 2020

Cited by 34 | Viewed by 3815

Abstract

Adenosine triphosphate-binding cassette transporters (ABC transporters) participate in various plant growth and abiotic stress responses. In the present study, 131 ABC genes in barley were systematically identified using bioinformatics. Based on the classification method of the family in rice, these members were classified [...] Read more.

Adenosine triphosphate-binding cassette transporters (ABC transporters) participate in various plant growth and abiotic stress responses. In the present study, 131 ABC genes in barley were systematically identified using bioinformatics. Based on the classification method of the family in rice, these members were classified into eight subfamilies (ABCA–ABCG, ABCI). The conserved domain, amino acid composition, physicochemical properties, chromosome distribution, and tissue expression of these genes were predicted and analyzed. The results showed that the characteristic motifs of the barley ABC genes were highly conserved and there were great diversities in the homology of the transmembrane domain, the number of exons, amino acid length, and the molecular weight, whereas the span of the isoelectric point was small. Tissue expression profile analysis suggested that ABC genes possess non-tissue specificity. Ultimately, 15 differentially expressed genes exhibited diverse expression responses to stress treatments including drought, cadmium, and salt stress, indicating that the ABCB and ABCG subfamilies function in the response to abiotic stress in barley. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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14 pages, 12679 KiB

Open AccessArticle

Chlorophyll a Fluorescence Transient and 2-Dimensional Electrophoresis Analyses Reveal Response Characteristics of Photosynthesis to Heat Stress in Malus. ‘Prairifire’

by Tao Wang, Siqian Luo, Yingli Ma, Lingyu Li, Yinfeng Xie and Wangxiang Zhang

Plants 2020, 9(8), 1040; https://doi.org/10.3390/plants9081040 - 15 Aug 2020

Cited by 7 | Viewed by 2424

Abstract

Flowering crabapples are a series of precious ornamental woody plants. However, their growth and development are inhibited in the subtropical regions due to the weak photosynthesis under high-temperature environment in the summer. Chlorophyll a fluorescence transient and 2-dimensional electrophoresis (2-DE) analyses were conducted [...] Read more.

Flowering crabapples are a series of precious ornamental woody plants. However, their growth and development are inhibited in the subtropical regions due to the weak photosynthesis under high-temperature environment in the summer. Chlorophyll a fluorescence transient and 2-dimensional electrophoresis (2-DE) analyses were conducted to investigate the response characteristics of photosynthesis under simulated 38 °C heat stress in leaves of Malus. ‘Prairifire’, a spring-red leaf cultivar of flowering crabapple with strong thermal adaptability. In the present study, the net photosynthetic rate (Pn) was significantly decreased during the heat shock process, which showed a similar trend to the stomatal conductance (Gs), indicating a sensitive stomatal behavior to heat stress. Moreover, an efficient reaction center in photosystem II (PSII), and a functionally intact oxygen-evolving complex (OEC) conferred strong photosynthetic adaptability under heat stress. The higher level of transketolase (TK) under 48-h heat shock treatment was considered a protective mechanism of photosynthetic apparatus. However, heat stress inhibited the functions of light harvesting complex II (LHCII), electron transport in PSII, and the levels of key enzymes in the Calvin cycle, which were considered as the reasons causing an increase in the proportion of non-stomatal restrictions. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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15 pages, 2971 KiB

Open AccessArticle

Genome-Wide Identification and Functional Characterization of the Heat Shock Factor Family in Eggplant (Solanum melongena L.) under Abiotic Stress Conditions

by Jinglei Wang, Haijiao Hu, Wuhong Wang, Qingzhen Wei, Tianhua Hu and Chonglai Bao

Plants 2020, 9(7), 915; https://doi.org/10.3390/plants9070915 - 20 Jul 2020

Cited by 12 | Viewed by 3155

Abstract

Plant heat shock factors (Hsfs) play crucial roles in various environmental stress responses. Eggplant (Solanum melongena L.) is an agronomically important and thermophilic vegetable grown worldwide. Although the functions of Hsfs under environmental stress conditions have been characterized in the model plant [...] Read more.

Plant heat shock factors (Hsfs) play crucial roles in various environmental stress responses. Eggplant (Solanum melongena L.) is an agronomically important and thermophilic vegetable grown worldwide. Although the functions of Hsfs under environmental stress conditions have been characterized in the model plant Arabidopsis thaliana and tomato, their roles in responding to various stresses remain unclear in eggplant. Therefore, we characterized the eggplant SmeHsf family and surveyed expression profiles mediated by the SmeHsfs under various stress conditions. Here, using reported Hsfs from other species as queries to search SmeHsfs in the eggplant genome and confirming the typical conserved domains, we identified 20 SmeHsf genes. The SmeHsfs were further classified into 14 subgroups on the basis of their structure. Additionally, quantitative real-time PCR revealed that SmeHsfs responded to four stresses—cold, heat, salinity and drought—which indicated that SmeHsfs play crucial roles in improving tolerance to various abiotic stresses. The expression pattern of SmeHsfA6b exhibited the most immediate response to the various environmental stresses, except drought. The genome-wide identification and abiotic stress-responsive expression pattern analysis provide clues for further analysis of the roles and regulatory mechanism of SmeHsfs under environmental stresses. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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15 pages, 2968 KiB

Open AccessArticle

Transcriptome Analysis of High-NUE (T29) and Low-NUE (T13) Genotypes Identified Different Responsive Patterns Involved in Nitrogen Stress in Ramie (Boehmeria nivea (L.) Gaudich)

by Longtao Tan, Gang Gao, Chunming Yu, Aiguo Zhu, Ping Chen, Kunmei Chen, Jikang Chen and Heping Xiong

Plants 2020, 9(6), 767; https://doi.org/10.3390/plants9060767 - 19 Jun 2020

Cited by 3 | Viewed by 2628

Abstract

Nitrogen-use efficiency (NUE) has significant impacts on plant growth and development. NUE in plants differs substantially in physiological resilience to nitrogen stress; however, the molecular mechanisms underlying enhanced resilience of high-NUE plants to nitrogen deficiency remains unclear. We compared transcriptome-wide gene expression between [...] Read more.

Nitrogen-use efficiency (NUE) has significant impacts on plant growth and development. NUE in plants differs substantially in physiological resilience to nitrogen stress; however, the molecular mechanisms underlying enhanced resilience of high-NUE plants to nitrogen deficiency remains unclear. We compared transcriptome-wide gene expression between high-NUE and low-NUE ramie (Boehmeria nivea (L.) Gaudich) genotypes under nitrogen (N)-deficient and normal conditions to identify the transcriptomic expression patterns that contribute to ramie resilience to nitrogen deficiency. Two ramie genotypes with contrasting NUE were used in the study, including T29 (NUE = 46.01%) and T13 (NUE = 15.81%). Our results showed that high-NUE genotypes had higher gene expression under the control condition across 94 genes, including frontloaded genes such as GDSL esterase and lipase, gibberellin, UDP-glycosyltransferase, and omega-6 fatty acid desaturase. Seventeen stress-tolerance genes showed lower expression levels and varied little in response to N-deficiency stress in high-NUE genotypes. In contrast, 170 genes were upregulated under N deficiency in high-NUE genotypes but downregulated in low-NUE genotypes compared with the controls. Furthermore, we identified the potential key genes that enable ramie to maintain physiological resilience under N-deficiency stress, and categorized these genes into three groups based on the transcriptome and their expression patterns. The transcriptomic and clustering analysis of these nitrogen-utilization-related genes could provide insight to better understand the mechanism of linking among the three gene classes that enhance resilience in high-NUE ramie genotypes. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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16 pages, 2917 KiB

Open AccessArticle

Shoot Characterization of Isoprene and Ocimene-Emitting Transgenic Arabidopsis Plants under Contrasting Environmental Conditions

by Michele Faralli, Mingai Li and Claudio Varotto

Plants 2020, 9(4), 477; https://doi.org/10.3390/plants9040477 - 9 Apr 2020

Cited by 8 | Viewed by 2730

Abstract

Isoprenoids are among the most abundant biogenic volatile compounds (VOCs) emitted by plants, and mediate both biotic and abiotic stress responses. Here, we provide for the first time a comparative analysis of transgenic Arabidopsis lines constitutively emitting isoprene and ocimene. Transgenic lines and [...] Read more.

Isoprenoids are among the most abundant biogenic volatile compounds (VOCs) emitted by plants, and mediate both biotic and abiotic stress responses. Here, we provide for the first time a comparative analysis of transgenic Arabidopsis lines constitutively emitting isoprene and ocimene. Transgenic lines and Columbia-0 (Col-0) Arabidopsis were characterized under optimal, water stress, and heat stress conditions. Under optimal conditions, the projected leaf area (PLA), relative growth rate, and final dry weight were generally higher in transgenics than Col-0. These traits were associated to a larger photosynthetic capacity and CO₂ assimilation rate at saturating light. Isoprene and ocimene emitters displayed a moderately higher stress tolerance than Col-0, showing higher PLA and gas-exchange traits throughout the experiments. Contrasting behaviors were recorded for the two overexpressors under water stress, with isoprene emitters showing earlier stomatal closure (conservative behavior) than ocimene emitters (non-conservative behavior), which might suggest different induced strategies for water conservation and stress adaptation. Our work indicates that (i) isoprene and ocimene emitters resulted in enhanced PLA and biomass under optimal and control conditions and that (ii) a moderate stress tolerance is induced when isoprene and ocimene are constitutively emitted in Arabidopsis, thus providing evidence of their role as a potential preferable trait for crop improvement. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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17 pages, 4665 KiB

Open AccessArticle

Effects of Rhizome Integration on the Water Physiology of Phyllostachys edulis Clones Under Heterogeneous Water Stress

by Xiong Jing, Chunju Cai, Shaohui Fan, Guanglu Liu, Changming Wu and Benxue Chen

Plants 2020, 9(3), 373; https://doi.org/10.3390/plants9030373 - 18 Mar 2020

Cited by 5 | Viewed by 2995

Abstract

Water is crucial to plant growth and development. Under heterogeneous environmental water deficiency, physiological integration of the rhizomatous clonal plant triggers a series of physiological cascades, which induces both signaling and physiological responses. It is known that the rhizome of Phyllostachys edulis, [...] Read more.

Water is crucial to plant growth and development. Under heterogeneous environmental water deficiency, physiological integration of the rhizomatous clonal plant triggers a series of physiological cascades, which induces both signaling and physiological responses. It is known that the rhizome of Phyllostachys edulis, which connects associated clonal ramets, has important significance in this physiological integration. This significance is attributed to the sharing of water and nutrients in the vascular bundle of clonal ramets under heterogeneous water conditions. However, the physiological characteristics of physiological integration under heterogeneous water stress remain unclear. To investigate these physiological characteristics, particularly second messenger Ca²⁺ signaling characteristics, long-distance hormone signaling molecules, antioxidant enzyme activity, osmotic adjustment substance, and nitrogen metabolism, ramets with a connected (where integration was allowed to take place) and severed rhizome (with no integration) were compared in this study. The vascular bundle structure of the rhizome was also observed using laser confocal microscopy. Overall, the results suggest that interconnected rhizome of P. edulis can enhance its physiological function in response to drought-induced stress under heterogeneous water deficiency. These measured changes in physiological indices serve to improve the clonal ramets’ drought adaptivity through the interconnected rhizome. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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15 pages, 1756 KiB

Open AccessEditor’s ChoiceReview

Function and Mechanism of WRKY Transcription Factors in Abiotic Stress Responses of Plants

by Weixing Li, Siyu Pang, Zhaogeng Lu and Biao Jin

Plants 2020, 9(11), 1515; https://doi.org/10.3390/plants9111515 - 8 Nov 2020

Cited by 198 | Viewed by 13720

Abstract

The WRKY gene family is a plant-specific transcription factor (TF) group, playing important roles in many different response pathways of diverse abiotic stresses (drought, saline, alkali, temperature, and ultraviolet radiation, and so forth). In recent years, many studies have explored the role and [...] Read more.

The WRKY gene family is a plant-specific transcription factor (TF) group, playing important roles in many different response pathways of diverse abiotic stresses (drought, saline, alkali, temperature, and ultraviolet radiation, and so forth). In recent years, many studies have explored the role and mechanism of WRKY family members from model plants to agricultural crops and other species. Abiotic stress adversely affects the growth and development of plants. Thus, a review of WRKY with stress responses is important to increase our understanding of abiotic stress responses in plants. Here, we summarize the structural characteristics and regulatory mechanism of WRKY transcription factors and their responses to abiotic stress. We also discuss current issues and future perspectives of WRKY transcription factor research. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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10 pages, 2255 KiB

Open AccessBrief Report

An Abiotic Stress Responsive U-Box E3 Ubiquitin Ligase Is Involved in OsGI-Mediating Diurnal Rhythm Regulating Mechanism

by Yo-Han Yoo, Xu Jiang and Ki-Hong Jung

Plants 2020, 9(9), 1071; https://doi.org/10.3390/plants9091071 - 20 Aug 2020

Cited by 8 | Viewed by 3304

Abstract

The plant U-box (PUB) protein is the E3 ligase that plays roles in the degradation or post-translational modification of target proteins. In rice, 77 U-box proteins were identified and divided into eight classes according to the domain configuration. We performed a phylogenomic analysis [...] Read more.

The plant U-box (PUB) protein is the E3 ligase that plays roles in the degradation or post-translational modification of target proteins. In rice, 77 U-box proteins were identified and divided into eight classes according to the domain configuration. We performed a phylogenomic analysis by integrating microarray expression data under abiotic stress to the phylogenetic tree context. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) expression analyses identified that eight, twelve, and eight PUB family genes are associated with responses to drought, salinity, and cold stress, respectively. In total, 16 genes showed increased expression in response to three abiotic stresses. Among them, the expression of OsPUB2 in class II and OsPUB33, OsPUB39, and OsPUB41 in class III increased in all three abiotic stresses, indicating their involvement in multiple abiotic stress regulation. In addition, we identified the circadian rhythmic expression for three out of 16 genes responding to abiotic stress through meta-microarray expression data analysis. Among them, OsPUB4 is predicted to be involved in the rice GIGANTEA (OsGI)-mediating diurnal rhythm regulating mechanism. In the last, we constructed predicted protein-protein interaction networks associated with OsPUB4 and OsGI. Our analysis provides essential information to improve environmental stress tolerance mediated by the PUB family members in rice. Full article

(This article belongs to the Special Issue Responses of Plants to Environmental Stresses)

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