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1.
Nat Commun ; 11(1): 4945, 2020 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-33009378

RESUMO

Spring warming substantially advances leaf unfolding and flowering time for perennials. Winter warming, however, decreases chilling accumulation (CA), which increases the heat requirement (HR) and acts to delay spring phenology. Whether or not this negative CA-HR relationship is correctly interpreted in ecosystem models remains unknown. Using leaf unfolding and flowering data for 30 perennials in Europe, here we show that more than half (7 of 12) of current chilling models are invalid since they show a positive CA-HR relationship. The possible reason is that they overlook the effect of freezing temperature on dormancy release. Overestimation of the advance in spring phenology by the end of this century by these invalid chilling models could be as large as 7.6 and 20.0 days under RCPs 4.5 and 8.5, respectively. Our results highlight the need for a better representation of chilling for the correct understanding of spring phenological responses to future climate change.


Assuntos
Mudança Climática , Temperatura Baixa , Folhas de Planta/fisiologia , Estações do Ano , Betula/fisiologia , Temperatura Alta , Modelos Lineares , Modelos Biológicos
2.
Nat Commun ; 11(1): 4140, 2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32811829

RESUMO

Investigating the evolution of complex phenotypes and the underlying molecular bases of their variation is critical to understand how organisms adapt to their environment. Applying classical quantitative genetics on a segregating population derived from a Can-0xCol-0 cross, we identify the MADS-box transcription factor FLOWERING LOCUS M (FLM) as a player of the phenotypic variation in plant growth and color. We show that allelic variation at FLM modulates plant growth strategy along the leaf economics spectrum, a trade-off between resource acquisition and resource conservation, observable across thousands of plant species. Functional differences at FLM rely on a single intronic substitution, disturbing transcript splicing and leading to the accumulation of non-functional FLM transcripts. Associations between this substitution and phenotypic and climatic data across Arabidopsis natural populations, show how noncoding genetic variation at a single gene might be adaptive through pleiotropic effects.


Assuntos
Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Regulação da Expressão Gênica de Plantas/genética , Proteínas de Domínio MADS/genética , Proteínas de Domínio MADS/metabolismo , Processamento de RNA/genética , Alelos , Arabidopsis/metabolismo , Evolução Molecular , Pleiotropia Genética , Variação Genética , Íntrons , Fenótipo , Folhas de Planta/genética , Folhas de Planta/fisiologia , Locos de Características Quantitativas/genética , Temperatura
3.
PLoS One ; 15(7): e0236813, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32726342

RESUMO

High salt accumulation, resulting from the rampant use of chemical fertilizers in greenhouse cultivation, has deleterious effects on plant growth and crop yield. Herein, we delineated the effects of magnesium (Mg) oversupply on Perilla frutescens leaves, a traditional edible and medicinal herb used in East-Asian countries. Mg oversupply resulted in significantly higher chlorophyll content coupled with lower antioxidant activities and growth, suggesting a direct effect on subtle metabolomes. The relative abundance of bioactive phytochemicals, such as triterpenoids, flavonoids, and cinnamic acids, was lower in the Mg-oversupplied plants than in the control. Correlation analysis between plant phenotypes (plant height, total fresh weight of the shoot, leaf chlorophyll content, and leaf antioxidant content) and the altered metabolomes in P. frutescens leaves suggested an acclimatization mechanism to Mg oversupply. In conclusion, P. frutescens preferentially accumulated compatible solutes, i.e., carbohydrates and amino acids, to cope with higher environmental Mg levels, instead of employing secondary and antioxidative metabolism.


Assuntos
Aclimatação/efeitos dos fármacos , Magnésio/farmacologia , Metabolômica , Perilla frutescens/efeitos dos fármacos , Perilla frutescens/metabolismo , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/metabolismo , Antioxidantes/metabolismo , Relação Dose-Resposta a Droga , Perilla frutescens/crescimento & desenvolvimento , Perilla frutescens/fisiologia , Fenótipo , Folhas de Planta/fisiologia
4.
PLoS One ; 15(7): e0235795, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32645115

RESUMO

To investigate the growth, physiological changes and mechanism of drought resistance of Camellia oleifera GWu-2 under drought stress conditions, changes in the main growth and physiological indices of GWu-2 under different water gradients were studied. Factor analysis was used to study the differences between indicators under different water gradients, and correlation analysis was implemented to analyze the relationship between different factors. We observed that the growth state, enzyme secretion, stomatal morphology and leaf osmotic adjustment substances were significantly affected by drought stress. In particular, increases in leaf abscisic acid (ABA), indole acetic acid (IAA) and methyl jasmonate (MeJA) contents under drought stress were negatively correlated with the stomatal opening degree, and the ratio of ZR/GA3 was significantly correlated with the growth and physiological indicators of GWu-2, indicating that different hormones respond differently to drought stress and have different functions in the growth regulation and drought resistance of GWu-2. We concluded that the drought resistance mechanism of GWu-2 was controlled by maintaining root growth to obtain the necessary water, increasing the contents of osmotic substances of leaves to maintain water holding capacity, reducing the transpiration of water by increasing leaf ABA, IAA and MeJA content to close stomata and reducing the damage caused by drought by increasing the activity of superoxide dismutase (SOD).


Assuntos
Aclimatação , Camellia/fisiologia , Ácido Abscísico/metabolismo , Acetatos/metabolismo , Camellia/crescimento & desenvolvimento , Ciclopentanos/metabolismo , Secas , Ácidos Indolacéticos/metabolismo , Oxilipinas/metabolismo , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Estômatos de Plantas/crescimento & desenvolvimento , Estômatos de Plantas/fisiologia , Estresse Fisiológico , Água/metabolismo
5.
PLoS One ; 15(7): e0235441, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32614866

RESUMO

Although seagrasses are economically and ecologically critical species, little is known about their blade surface microbial communities and how these communities relate to the plant host. To determine microbial community composition and diversity on seagrass blade surfaces and in the surrounding seawater,16S rRNA gene sequencing (iTag) was used for samples collected at five sites along a gradient of freshwater input in the northern Gulf of Mexico on three separate sampling dates. Additionally, seagrass surveys were performed and environmental parameters were measured to characterize host characteristics and the abiotic conditions at each site. Results showed that Thalassia testudinum (turtle grass) blades hosted unique microbial communities that were distinct in composition and diversity from the water column. Environmental conditions, including water depth, salinity, and temperature, influenced community structure as blade surface microbial communities varied among sites and sampling dates in correlation with changes in environmental parameters. Microbial community composition also correlated with seagrass host characteristics, including growth rates and blade nutrient composition. There is some evidence for a core community for T. testudinum as 21 microorganisms from five phyla (Cyanobacteria, Proteobacteria, Planctomycetes, Chloroflexi, and Bacteroidetes) were present in all blade surface samples. This study provides new insights and understanding of the processes that influence the structure of marine phyllosphere communities, how these microbial communities relate to their host, and their role as a part of the seagrass holobiont, which is an important contribution given the current decline of seagrass coverage worldwide.


Assuntos
Bactérias/classificação , Água Doce/microbiologia , Hydrocharitaceae/microbiologia , Microbiota , Folhas de Planta/microbiologia , Água do Mar/microbiologia , Bactérias/genética , Golfo do México , Interações entre Hospedeiro e Microrganismos , Hydrocharitaceae/fisiologia , Filogenia , Folhas de Planta/fisiologia , RNA Ribossômico 16S/genética , Salinidade , Áreas Alagadas
6.
PLoS One ; 15(7): e0235928, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32697785

RESUMO

Several species of dryland cyanobacteria are known to occur as hypoliths under semi-translucent rocks. In the Mojave Desert, these organisms find refuge from intense solar radiation under milky quartz where moisture persists for a longer period of time than in adjacent soil surface habitat. Desert mosses, which are extremely desiccation-tolerant, can also occur in these hypolithic spaces, though little is known about this unique moss microhabitat and how species composition compares to that of adjacent soil surface communities. To address this question, we deployed microclimate dataloggers and collected moss samples from under and adjacent to 18 milky quartz rocks (quartz mean center thickness 26 ± 15 mm) in a western high elevation Mojave Desert site. Light transmission through Mojave quartz rocks may be as low as 1.2%, and data from microclimate loggers deployed for five months support the hypothesis that quartz provides thermal buffering and higher relative humidity compared to the soil surface. Of the 53 samples collected from hypolith and surface microhabitats, 68% were Syntrichia caninervis, the dominant bryophyte of the Mojave Desert biological soil crust. Tortula inermis accounted for 28% of the samples and 4% were Bryum argenteum. In a comparison of moss community composition, we found that S. caninervis was more likely to be on the soil surface, though it was abundant in both microhabitats, while T. inermis was more restricted to hypoliths, perhaps due to protection from temperature extremes. In our study site, the differences between hypolithic and surface microhabitats enable niche partitioning between T. inermis and S. caninervis, enhancing alpha diversity. This work points to the need to thoroughly consider microhabitats when assessing bryophyte species diversity and modelling species distributions. This focus is particularly important in extreme environments, where mosses may find refuge from the prevailing macroclimatic conditions in microhabitats such as hypoliths.


Assuntos
Briófitas/crescimento & desenvolvimento , Clima Desértico , Quartzo/química , Briófitas/fisiologia , Ecossistema , Umidade , Microclima , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/fisiologia , Solo/química
7.
PLoS One ; 15(7): e0227785, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32673318

RESUMO

A panel of 60 genotypes comprising New Plant Types (NPTs) along with indica, tropical and temperate japonica genotypes was phenotypically evaluated for four seasons in irrigated situation for grain yield per se and component traits. Twenty NPT genotypes were found promising with an average grain yield varying from 5.45 to 8.8 t/ha. A total of 85 SSR markers were used in the study to identify QTLs associated with grain yield per se and related traits. Sixty-six (77.65%) markers were found to be polymorphic. The PIC values varied from 0.516 to 0.92 with an average of 0.704. A moderate level of genetic diversity (0.39) was detected among genotypes. Variation to the tune of 8% within genotypes, 68% among the genotypes within the population and 24% among the populations were observed (AMOVA). This information may help in identification of potential parents for development of transgressive segregants with very high yield. The association analysis using GLM and MLM models led to the identification of 30 and 10 SSR markers associated with 70 and 16 QTLs, respectively. Thirty novel QTLs linked with 16 SSRs were identified to be associated with eleven traits, namely tiller number (qTL-6.1, qTL-11.1, qTL-4.1), panicle length (qPL-1.1, qPL-5.1, qPL-7.1, qPL-8.1), flag leaf length (qFLL-8.1, qFLL-9.1), flag leaf width (qFLW-6.2, qFLW-5.1, qFLW-8.1, qFLW-7.1), total no. of grains (qTG-2.2, qTG-a7.1), thousand-grain weight (qTGW-a1.1, qTGW-a9.2, qTGW-5.1, qTGW-8.1), fertile grains (qFG-7.1), seed length-breadth ratio (qSlb-3.1), plant height (qPHT-6.1, qPHT-9.1), days to 50% flowering (qFD-1.1) and grain yield per se (qYLD-5.1, qYLD-6.1a, qYLD-11.1).Some of the SSRs were co-localized with more than two traits. The highest co-localization was identified with RM5709 linked to nine traits, followed by RM297 with five traits. Similarly, RM5575, RM204, RM168, RM112, RM26499 and RM22899 were also recorded to be co-localized with more than one trait and could be rated as important for marker-assisted backcross breeding programs, for pyramiding of these QTLs for important yield traits, to produce new-generation rice for prospective increment in yield potentiality and breaking yield ceiling.


Assuntos
Oryza/genética , Locos de Características Quantitativas , Grão Comestível/genética , Variação Genética , Genótipo , Repetições de Microssatélites/genética , Oryza/fisiologia , Fenótipo , Folhas de Planta/genética , Folhas de Planta/fisiologia , Análise de Componente Principal
8.
PLoS One ; 15(6): e0232633, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32555651

RESUMO

Maize, a main crop worldwide, establishes a mutualistic symbiosis with arbuscular mycorrhizal (AM) fungi providing nutrients to the roots from soil volumes which are normally not in reach of the non-colonized root. The mycorrhizal phosphate uptake pathway (MPU) spans from extraradical hyphae to root cortex cells housing fungal arbuscules and promotes the supply of phosphate to the mycorrhizal host in exchange for photosynthetic carbon. This symbiotic association with the mycobiont has been shown to affect plant host nutritional status and growth performance. However, whether and how the MPU affects the root microbial community associated with mycorrhizal hosts in association with neighboring plants, remains to be demonstrated. Here the maize germinal Mu transposon insertion mutant pht1;6, defective in mycorrhiza-specific Pi transporter PHT1;6 gene, and wild type B73 (wt) plants were grown in mono- and mixed culture and examined under greenhouse and field conditions. Disruption of the MPU in pht1;6 resulted in strongly diminished growth performance, in reduced P allocation to photosynthetic source leaves, and in imbalances in leaf elemental composition beyond P. At the microbial community level a loss of MPU activity had a minor effect on the root-associated fungal microbiome which was almost fully restricted to AM fungi of the Glomeromycotina. Moreover, while wt grew better in presence of pht1;6, pht1;6 accumulated little biomass irrespective of whether it was grown in mono- or mixed culture and despite of an enhanced fungal colonization of its roots in co-culture with wt. This suggested that a functional MPU is prerequisite to maintain maize growth and that neighboring plants competed for AM fungal Pi in low P soil. Thus future strategies towards improving yield in maize populations on soils with low inputs of P fertilizer could be realized by enhancing MPU at the individual plant level while leaving the root-associated fungal community largely unaffected.


Assuntos
Micorrizas/metabolismo , Fosfatos/metabolismo , Zea mays/microbiologia , Zea mays/fisiologia , Biomassa , Mutação com Perda de Função , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Plantas Geneticamente Modificadas , Solo/química , Simbiose/fisiologia , Zea mays/genética , Zea mays/crescimento & desenvolvimento
9.
PLoS One ; 15(6): e0233735, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32497128

RESUMO

Many fertilization models have been created to scientifically determine the amount of fertilization. With the same purpose, we constructed a nitrogen (N) application model, the leaf value model, which can make N fertilizer decisions in a timely, fast and nondestructive manner during rice planting. However, only one area (A1, Jiuzhou Town, Xixiu District, Guizhou Province) and one cultivar (Qyou6) were involved in the construction of the leaf value model. Its stability and applicability could not be well evaluated. Thus, we chose another area (A2, Jiuzhou Town, Huangping County, Guizhou Province) in Guizhou Province and carried out the experiment by using four cultivars (Nie5you5399, Qyou6, Yixiangyou2115 and Zhongzheyou8) for the leaf value model construction. Compared with the average value of apparent total N uptake (Nz) obtained in 2 years in the A1 area, that in the Qyou6 leaf value model in the A2 area increased by 12%, reaching 635.72 kg ha-1, whereas the corresponding target yield changed slightly, reaching 10,999.90 kg ha-1. Simultaneously, the linear relationship between several good SPAD value-derived indexes (Ys) and apparent N supply of the field (Nx) was still significant or extremely significant in the Qyou6 leaf value model. Compared with the A1 area, it slightly differed, and the R2 of SPADL1 was higher than that of SPADL3×L4/mean. In the leaf value model of the other three cultivars, the relationship between yield and Nx and that between Ys and Nx were significant or extremely significant. The Nz of Yixiangyou2115 and Zhongzheyou8 (618.33 and 617.76 kg ha-1) were close to that of Qyou6 and the corresponding target yields were 10313.36 and 10301.99 kg ha-1, respectively. The Nz and target yield of Nie5you5399 were lowest at 546.63 and 10680.24 kg ha-1, respectively. In general, this study showed that relationships used in the construction of leaf value model had certain stability and applicability to difference areas and cultivars. The leaf value model can be considered in N fertilizer decision-making of rice planting management.


Assuntos
Fertilizantes , Modelos Biológicos , Nitrogênio/administração & dosagem , Oryza/fisiologia , Folhas de Planta/fisiologia , Clorofila/análise , Produção Agrícola/métodos , Oryza/anatomia & histologia , Oryza/química , Folhas de Planta/química , Solo/química
10.
Proc Natl Acad Sci U S A ; 117(27): 16035-16042, 2020 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-32571929

RESUMO

The mechanical principles for fast snapping in the iconic Venus flytrap are not yet fully understood. In this study, we obtained time-resolved strain distributions via three-dimensional digital image correlation (DIC) for the outer and inner trap-lobe surfaces throughout the closing motion. In combination with finite element models, the various possible contributions of the trap tissue layers were investigated with respect to the trap's movement behavior and the amount of strain required for snapping. Supported by in vivo experiments, we show that full trap turgescence is a mechanical-physiological prerequisite for successful (fast and geometrically correct) snapping, driven by differential tissue changes (swelling, shrinking, or no contribution). These are probably the result of the previous accumulation of internal hydrostatic pressure (prestress), which is released after trap triggering. Our research leads to an in-depth mechanical understanding of a complex plant movement incorporating various actuation principles.


Assuntos
Droseraceae/fisiologia , Movimento/fisiologia , Folhas de Planta/fisiologia , Fenômenos Biomecânicos , Simulação por Computador , Modelos Biológicos , Movimento (Física) , Fatores de Tempo , Gravação em Vídeo
11.
Artigo em Inglês | MEDLINE | ID: mdl-32485617

RESUMO

High relative air humidity (RH ≥ 85%) is frequent in controlled environments, and not uncommon in nature. In this review, we examine the high RH effects on plants with a special focus on stomatal characters. All aspects of stomatal physiology are attenuated by elevated RH during leaf expansion (long-term) in C3 species. These include impaired opening and closing response, as well as weak diel oscillations. Consequently, the high RH-grown plants are not only vulnerable to biotic and abiotic stress, but also undergo a deregulation between CO2 uptake and water loss. Stomatal behavior of a single leaf is determined by the local microclimate during expansion, and may be different than the remaining leaves of the same plant. No effect of high RH is apparent in C4 and CAM species, while the same is expected for species with hydropassive stomatal closure. Formation of bigger stomata with larger pores is a universal response to high RH during leaf expansion, whereas the effect on stomatal density appears to be species- and leaf side-specific. Compelling evidence suggests that ABA mediates the high RH-induced stomatal malfunction, as well as the stomatal size increase. Although high RH stimulates leaf ethylene evolution, it remains elusive whether or not this contributes to stomatal malfunction. Most species lose stomatal function following mid-term (4-7 d) exposure to high RH following leaf expansion. Consequently, the regulatory role of ambient humidity on stomatal functionality is not limited to the period of leaf expansion, but holds throughout the leaf life span.


Assuntos
Umidade , Estômatos de Plantas/fisiologia , Transpiração Vegetal , Ácido Abscísico , Folhas de Planta/fisiologia , Água
12.
Artigo em Inglês | MEDLINE | ID: mdl-32594380

RESUMO

Influence of arsenic (As) in As tolerant and sensitive rice genotypes based chloroplastic pigments, leaf gas exchange attributes and their influence on carbohydrate metabolism were investigated in the present study. As retards growth of crop plants and increase several health ailments by contaminating food chain. Photosynthetic inhibition is known to be the prime target of As toxicity due to over-production of ROS. Hydroponically grown rice seedlings of twelve cultivars were exposed to 25, 50, and 75 µM arsenate (AsV) that exerted negative impact on plastidial pigments content and resulted into inhibition of Hill activity. Internal CO2 concentration lowered gradually due to interference of As with stomatal conductance and transpiration rate that subsequently led to drop in net photosynthesis. Twelve contrasting rice genotypes responded differentially to As(V) stress. Present study evaluated As tolerant and sensitive rice cultivars with respect to As(V) imposed alterations in pigments content, photosynthetic attributes along with sugar metabolism. Starch contents, the principle carbohydrate storage declined differentially among As(V) stressed test cultivars, being more pronounced in cvs. Swarnadhan, Tulaipanji, Pusa basmati, Badshabhog, Tulsibhog and IR-20 compared to cvs. Bhutmuri, Kumargore, Binni, Vijaya, TN-1 and IR-64. Therefore, the six former cultivars tried to adapt defensive mechanisms by accumulating higher levels of reducing and non-reducing sugars to carry out basal metabolism to withstand As(V) induced alterations in photosynthesis. This study could help to screen As tolerant and sensitive rice genotypes based on their photosynthetic efficiency in As polluted agricultural fields to reduce As contamination assisted ecotoxicological risk.


Assuntos
Arseniatos/efeitos adversos , Metabolismo dos Carboidratos/efeitos dos fármacos , Oryza/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Poluentes do Solo/efeitos adversos , Genótipo , Oryza/genética , Oryza/fisiologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Plântula/fisiologia , Estresse Fisiológico
13.
Science ; 368(6493): 881-884, 2020 05 22.
Artigo em Inglês | MEDLINE | ID: mdl-32439792

RESUMO

Maintaining phenological synchrony with flowers is a key ecological challenge for pollinators that may be exacerbated by ongoing environmental change. Here, we show that bumble bee workers facing pollen scarcity damage leaves of flowerless plants and thereby accelerate flower production. Laboratory studies revealed that leaf-damaging behavior is strongly influenced by pollen availability and that bee-damaged plants flower significantly earlier than undamaged or mechanically damaged controls. Subsequent outdoor experiments showed that the intensity of damage inflicted varies with local flower availability; furthermore, workers from wild colonies of two additional bumble bee species were also observed to damage plant leaves. These findings elucidate a feature of bumble bee worker behavior that can influence the local availability of floral resources.


Assuntos
Abelhas/fisiologia , Comportamento Alimentar , Flores/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Pólen , Animais
14.
Chemosphere ; 251: 126310, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32443249

RESUMO

Arsenic-(As) pollution is an increasing threat across the globe and it is reaching harmful values in several areas of the world. In this perspective, we assayed bio-phyto-remediation technology using Arundo donax L., assisted by Plant Growth Promoting Bacteria (PGPB) consortium (BC) constituted of two strains of Stenotrophomonas maltophilia sp. and one of Agrobacterium sp.; furthermore, we assayed the epigenetic response to As pollution. The three bacterial strains initially evaluated for their As tolerance, revealed different resistance to both forms of As[As(III) and As(V)] however at concentration greater than those foreseen in the phytoremediation experiment (2.0, 10.0, 20.0 mgL-1 of NaAsO2). At the end of the trial plant biomass and As concentration were measured. Plants did not show any visible signs of toxicity, rather the leaf and stem biomass slightly increased in the presence of As and/or PGPBs; moreover, although the Bioaccumulation Factor was double in the presence of BC, the absolute values of As accumulation in the Arundo plants were very low, both in the presence or absence of BC and only detectable in the presence of the highest As dose (20 mgL-1 As). In this case, regardless the presence of PGPB, ≈25% of As remained in the sand and ≈0.15% was accumulated in the plant, whilst the remaining 75% was volatilized by transpiration. Finally, the methylation sensitive amplified polymorphisms (MSAP) of leaves were analyzed in order to investigate their epigenetic response to As and/or BC. Our results suggest that epigenetic modifications are involved in stress response and As detoxification.


Assuntos
Arsênico/metabolismo , Biodegradação Ambiental , Poaceae/fisiologia , Agrobacterium , Biomassa , Epigênese Genética , Folhas de Planta/fisiologia
15.
PLoS One ; 15(5): e0232974, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32401803

RESUMO

Heat stress along with low water availability at reproductive stage (terminal growth phase of wheat crop) is major contributing factor towards less wheat production in tropics and sub-tropics. Flag leaf plays a pivotal role in assimilate partitioning and stress tolerance of wheat during terminal growth phase. However, limited is known about biochemical response of flag leaf to combined and individual heat and drought stress during terminal growth phase. Therefore, current study investigated combined and individual effect of terminal drought and heat stress on water relations, photosynthetic pigments, osmolytes accumulation and antioxidants defense mechanism in flag leaf of bread wheat. Experimental treatments comprised of control, terminal drought stress alone (50% field capacity during reproductive phase), terminal heat stress alone (wheat grown inside plastic tunnel during reproductive phase) and terminal drought stress + terminal heat stress. Individual and combined imposition of drought and heat stresses significantly (p≤0.05) altered water relations, osmolyte contents, soluble proteins and sugars along with activated antioxidant defensive system in terms of superoxide dismutase (SOD), peroxidase (POD) and ascorbate peroxidase (APX). Turgor potential, POD and APX activities were lowest under individual heat stress; however, these were improved when drought stress was combined with heat stress. It is concluded that combined effect of drought and heat stress was more detrimental than individual stresses. The interactive effect of both stresses was hypo-additive in nature, but for some traits (like turgor potential and APX) effect of one stress neutralized the other. To best of our knowledge, this is the first report on physiological and biochemical response of flag leaf of wheat to combine heat and drought stress. These results will help future studies dealing with improved stress tolerance in wheat. However, detailed studies are needed to fully understand the genetic mechanisms behind these physiological and biochemical changes in flag leaf in response to combined heat and drought stress.


Assuntos
Triticum/crescimento & desenvolvimento , Triticum/fisiologia , Antioxidantes/metabolismo , Pão , Clorofila/metabolismo , Secas , Grão Comestível/crescimento & desenvolvimento , Grão Comestível/fisiologia , Resposta ao Choque Térmico/fisiologia , Fotossíntese , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/fisiologia , Água/metabolismo
16.
Artigo em Inglês | MEDLINE | ID: mdl-32449682

RESUMO

Growing conditions at different tree canopy positions may significantly vary and lead to foliar changes even within the same tree. An assessment of foliar anatomy, including also epidermal features, can help us understand how plants respond to environmental factors. Working with two model tree species (i.e., Quercus petraea and Fagus sylvatica) grown at their southernmost European distribution area in Central Spain, the influence of irradiation and canopy height was examined by sampling lower canopy leaves and comparing them with fully irradiated, top canopy leaves and shaded top canopy leaves grown for months within a bag made of shade netting fabric before they sprouted. At the end of the summer, samples were collected, and several parameters were analysed. The results indicate that SLA (specific leaf area) differences are significant both between species and groups. Leaf and cuticle thickness differed significantly between groups while stomatal densities only between species. Regarding mineral concentrations, differences between species were significant for K, Mn, N and N: P ratios. It is concluded that leaf responses to environmental conditions may be variable both within the same tree and between species.


Assuntos
Fagus , Folhas de Planta/anatomia & histologia , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Quercus , Escuridão , Fotossíntese , Estômatos de Plantas , Espanha , Luz Solar , Árvores
17.
Artigo em Inglês | MEDLINE | ID: mdl-32449683

RESUMO

The stomata of maize (Zea mays) contain a pair of guard cells and a pair of subsidiary cells. To determine whether H2O2, Ca2+, and K+ in subsidiary cells were involved in stomatal movement, we treated four-week-old maize (Zhengdan 958) leaves with H2O2, diphenylene iodonium (DPI), CaCl2, and LaCl3. Changes in content and distribution of H2O2, Ca2+, and K+ during stomatal movement were observed. When exogenous H2O2 was applied, Ca2+ increased and K+ decreased in guard cells, while both ions increased in subsidiary cells, leading to stomatal closure. After DPI treatment, Ca2+ decreased and K+ increased in guard cells, but both Ca2+ and K+ decreased in subsidiary cells, resulting in open stomata. Exogenous CaCl2 increased H2O2 and reduced K+ in guard cells, while significantly increasing them in subsidiary cells and causing stomatal closure. After LaCl3 treatment, H2O2 decreased and K+ increased in guard cells, whereas both decreased in subsidiary cells and stomata became open. Results indicate that H2O2 and Ca2+ correlate positively with each other and with K+ in subsidiary cells during stomatal movement. Both H2O2 and Ca2+ in subsidiary cells promote an inflow of K+, indirectly regulating stomatal closure.


Assuntos
Cálcio , Peróxido de Hidrogênio , Estômatos de Plantas/fisiologia , Potássio , Transdução de Sinais , Zea mays/fisiologia , Folhas de Planta/fisiologia
18.
J Plant Physiol ; 250: 153188, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32450394

RESUMO

Circular RNAs (circRNAs) are a newly characterized type of noncoding RNA and play important roles in microRNA (miRNA) function and transcriptional control. To unravel the mechanism of soybean circRNAs in low-temperature (LT) stress response, genome-wide identification of soybean circRNAs was conducted under LT (4 °C) treatment via deep sequencing. In this study, the existence of backsplicing sites was validated and circRNAs exhibited specific expression patterns in response to LT. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that circRNAs could participate in LT-responsive processes. Our study revealed a new circRNA-miRNA-mRNA network, which is involved in LT responses. Furthermore, soybean circRNAs were predicted to have potential to encode polypeptides or protein. Taken together, our results indicate that soybean circRNAs might encode proteins and be involved in the regulation of LT responses, providing clues regarding the molecular LT-responsive mechanisms in soybean.


Assuntos
Temperatura Baixa , RNA Circular/genética , RNA de Plantas/genética , Soja/fisiologia , Estresse Fisiológico/genética , Biologia Computacional , Sequenciamento de Nucleotídeos em Larga Escala , Folhas de Planta/genética , Folhas de Planta/fisiologia , RNA Circular/metabolismo , RNA de Plantas/metabolismo , Análise de Sequência de RNA , Soja/genética
19.
J Plant Physiol ; 250: 153164, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32460035

RESUMO

Although anthocyanin color patterns on flowers are among the most attractive characteristics, the genetic mechanisms through which color patterns are developed are not well understood, especially for color patterns associated with altered petal structure. Lilium species and cultivars often develop raised spots, where the interior surfaces of tepals increase to develop bumps with accompanying anthocyanin accumulation. The aim of this study was to identify transcription factors regulating pigmentation of the bumps. We identified two R2R3-MYB genes, MYB19Long and MYB19Short, in Lilium leichtlinii, L. lancifolium, and Asiatic hybrid lily cultivars. Their amino acid sequences were similar; however, part of the C-terminal region was triplicated in MYB19Long. Spatial and temporal expression profiles in lilies were strongly associated with anthocyanin biosynthesis gene expression in the bumps, and some defects were found in these genes in L. lancifolium 'Pure Gold' that developed colorless bumps. Thus, both MYB19Long and MYB19Short were likely to be involved in the bump pigmentation. MYB19Long had a stronger ability to stimulate target gene expression than MYB19Short, and expression levels of MYB19Long were greater than those of MYB19Short in lily tepals; thus, the ability to biosynthesize anthocyanin pigments was greater for MYB19Long than for MYB19Short. Among the F1 population, MYB19Short expression was found only in the tepals of F1 plants that developed bumps, although all of the F1 plants possessed the MYB19Short gene, indicating that MYB19 expression followed bump development. These findings helped to elucidate the genetic mechanisms underlying raised spot development.


Assuntos
Antocianinas/fisiologia , Lilium/fisiologia , Folhas de Planta/fisiologia , Proteínas de Plantas/genética , Fatores de Transcrição/genética , Sequência de Aminoácidos , Antocianinas/genética , Lilium/genética , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Alinhamento de Sequência , Especificidade da Espécie , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo
20.
J Plant Physiol ; 249: 153161, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32353607

RESUMO

Optical leaf profiles depend on foliar pigment type and content, as well as anatomical aspects and cellular ultrastructure, whose effects are shown in several species. Monocotyledon and Dicotyledon plants presenting natural pigment content variations and anatomical alterations were analyzed. Each plant species displays its own spectral signatures, which are, in turn, influenced by foliar pigment class (composition) and concentration, as well as anatomical and ultrastructural plant cell characteristics. Plants with no anthocyanin displayed increased reflectance and transmittance in the green spectral region (501-565 nm), while values decreased in the presence of anthocyanin. At wavelengths below 500 nm (350-500 nm), strong overlapping signatures of phenolics, carotenoids, chlorophylls, flavonoids and anthocyanins were observed. Using a partial least squares regression applied to 350-700 nm spectral data allowed for accurate estimations of different foliar pigment levels. In addition, a PCA and discriminant analysis were able to efficiently discriminate different species displaying spectra overlapping. The use of absorbance spectra only was able to discriminate species with 100 % confidence. Finally, a discussion on how different wavelengths are absorbed and on anatomical interference of light interaction in leaf profiles is presented.


Assuntos
Pigmentos Biológicos/análise , Folhas de Planta/fisiologia , Espectrofotometria/métodos , Cordyline/fisiologia , Philodendron/fisiologia , Poaceae/fisiologia , Especificidade da Espécie , Tradescantia/fisiologia
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