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1.
Sci Total Environ ; 700: 134453, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31670196

RESUMO

Heat stress induces secondary metabolic changes in plants, channeling photosynthetic carbon and energy, away from primary metabolic processes, including, growth. Use of ACC (1-aminocyclopropane-1-carboxylate) deaminase containing plant growth promoting bacteria (PGPB) in conferring heat resistance in plants and the role of PGPB, in altering net carbon assimilation, constitutive and stress volatile emissions has not been studied yet. We exposed leaves of Eucalyptus grandis inoculated and non-inoculated with PGPB Brevibacterium linens RS16 to two levels of heat stress (37 °C and 41 °C for 5 min) and quantified temporal changes in foliage photosynthetic characteristics and volatile emission rates at 0.5 h, day 1 and day 5 after the stress application. Heat stress resulted in immediate reductions in dark-adapted photosystem II (PSII) quantum yield (Fv/Fm), net assimilation rate (A), stomatal conductance to water vapor (gs), and enhancement of stress volatile emissions, including enhanced emissions of green leaf volatiles (GLV), mono- and sesquiterpenes, light weight oxygenated volatile organic compounds (LOC), geranyl-geranyl diphosphate pathway volatiles (GGDP), saturated aldehydes, and benzenoids, with partial recovery by day 5. Changes in stress-induced volatiles were always less in leaves inoculated with B. linens RS16. However, net assimilation rate was enhanced by bacterial inoculation only in the 37 °C treatment and overall reduction of isoprene emissions was observed in bacterially-treated leaves. Principal component analysis (PCA), correlation analysis and partial least squares discriminant analysis (PLS-DA) indicated that different stress applications influenced specific volatile organic compounds. In addition, changes in the expression analysis of heat shock protein 70 gene (DnaK) gene in B. linens RS16 upon exposure to higher temperatures further indicated that B. linens RS16 has developed its own heat resistance mechanism to survive under higher temperature regimes. Taken together, this study demonstrates that foliar application of ACC deaminase containing PGPB can ameliorate heat stress effects in realistic biological settings.


Assuntos
Brevibacterium/fisiologia , Eucalyptus/fisiologia , Resposta ao Choque Térmico , Estresse Fisiológico , Compostos Orgânicos Voláteis/análise , Carbono-Carbono Liases , Fotossíntese , Desenvolvimento Vegetal , Folhas de Planta
2.
Chemosphere ; 226: 891-897, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31509918

RESUMO

Eucalyptus globulus pre-treated by static magnetic fields of 30, 60, 120, 150 and 400 mT (mT) before sowing were used in a 45-day experiment to remediate soil containing Cd, Hg, Pb, Zn, Cr and Cu. The influence of magnetic fields on its remediation efficiency was evaluated. Magnetic fields with strength of 30, 60, 120 and 150 mT increased the biomass yield of the species by 3.1, 19.4, 48.1 and 60.9%, respectively, while 400 mT decreased the yield by 16.7%. Comparing with the control exposed only to the earth's geomagnetic field, all plants pre-treated by static magnetic field had significantly higher metal concentrations with the highest values achieved in the field of 400 mT. Higher transpiration rate of the plants along with exposure to static magnetic fields induced lower soil moisture content and was beneficial to environmental control because it could reduce the leachate during the phytoremediation process. Among all static magnetic field treatments, 150 mT was the best to improve the phytoremediation and alleviate the environmental risk, which shortened the time to purify Cd, Pb and Cu by 27.8-73.2%, 27.3-74.7% and 2.5-50.6%, respectively and intercepted 31.6-86.1% of the leachate. Therefore, static magnetic field with appropriate intensity is a suitable candidate to improve phytoremediation efficiency through enhancing the biomass production, toxin uptake and leachate interception.


Assuntos
Biodegradação Ambiental , Biomassa , Eucalyptus/fisiologia , Campos Magnéticos , Metais Pesados/análise , Poluentes do Solo/análise , Solo/química , Eucalyptus/crescimento & desenvolvimento
3.
Environ Sci Pollut Res Int ; 26(24): 24372-24379, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31230238

RESUMO

The Eucalyptus cultivation acreage was large in Guangxi provinces. Guanglin 9 (Eucalyptus grandis × Eucalyptus urophylla) is a widely cultivated Eucalyptus species and has been found to grow normally in soils contaminated by heavy metals such as arsenic (As), but the detoxification mechanisms are not clear yet. Through hydroponic experiment, the adsorption and detoxification of As in Eucalyptus were studied from three aspects, namely subcellular distribution of As, chemical forms of As, and the response of sulfhydryl substances. The subcellular distribution data showed that in the Eucalyptus roots, As was mainly present in the soluble fraction (66.3-79.9%), in leaves in the soluble fraction (50.6-53.8%), and the cell wall fraction (35.6-40.0%) under As stress. The chemical form data showed that in roots, As was mainly present in ethanol extraction state (29.5-40.0%), deionized water extraction state (28.3-31.7%), and sodium chloride extraction state (24.1-33.8%). As stress can induce the formation of non-protein thiols (NPT), glutathione (GSH), and phytochelatins (PCs). With the increasing As concentration, the NPT (maximum increase 55.9%) and GSH (maximum increase 79.9%) contents in roots significantly increased, while the PC content significantly increased and then significantly decreased. It is concluded that the As detoxification mechanisms of Eucalyptus are mainly vacuolar compartmentalization and the chelation of sulfhydryl substances, while cell wall adsorption and As chemical forms have limited effects on As detoxification.


Assuntos
Arsênico/toxicidade , Eucalyptus/fisiologia , Poluentes do Solo/toxicidade , Arsênico/análise , Parede Celular/metabolismo , Quelantes/farmacologia , China , Eucalyptus/efeitos dos fármacos , Glutationa/metabolismo , Hidroponia , Inativação Metabólica/fisiologia , Metais Pesados/análise , Fitoquelatinas/metabolismo , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Solo/química , Poluentes do Solo/análise , Compostos de Sulfidrila/metabolismo
4.
Am J Bot ; 106(6): 760-771, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31157413

RESUMO

PREMISE: Cambial activity in some tropical trees varies intra-annually, with the formation of xylem rings. Identification of the climatic factors that regulate cambial activity is important for understanding the growth of such species. We analyzed the relationship between climatic factors and cambial activity in four tropical hardwoods, Acacia mangium, Tectona grandis, Eucalyptus urophylla, and Neolamarckia cadamba in Yogyakarta, Java Island, Indonesia, which has a rainy season (November-June) and a dry season (July-October). METHODS: Small blocks containing phloem, cambium, and xylem were collected from main stems in January 2014, October 2015 and October 2016, and examined with light microscopy for cambial cell division, fusiform cambial cells, and expanding xylem cells as evidence of cambial activity. RESULTS: During the rainy season, when precipitation was high, cambium was active. By contrast, during the dry season in 2015, when there was no precipitation, cambium was dormant. However, in October 2016, during the so-called dry season, cambium was active, cell division was conspicuous, and a new xylem ring formation was initiated. The difference in cambial activity appeared to be related to an unusual pattern of precipitation during the typically dry months, from July to October, in 2016. CONCLUSIONS: Our results indicate that low or absent precipitation for 3 to 4 months induces cessation of cambial activity and temporal periodicity of wood formation in the four species studied. By contrast, in the event of continuing precipitation, cambial activity in the same trees may continue throughout the year. The frequency pattern of precipitation appears to be an important determinant of wood formation in tropical trees.


Assuntos
Câmbio/anatomia & histologia , Câmbio/fisiologia , Chuva , Árvores/anatomia & histologia , Árvores/fisiologia , Acacia/anatomia & histologia , Acacia/crescimento & desenvolvimento , Acacia/fisiologia , Câmbio/crescimento & desenvolvimento , Divisão Celular , Eucalyptus/anatomia & histologia , Eucalyptus/crescimento & desenvolvimento , Eucalyptus/fisiologia , Agricultura Florestal , Indonésia , Lamiaceae/anatomia & histologia , Lamiaceae/crescimento & desenvolvimento , Lamiaceae/fisiologia , Rubiaceae/anatomia & histologia , Rubiaceae/crescimento & desenvolvimento , Rubiaceae/fisiologia , Estações do Ano , Especificidade da Espécie , Árvores/crescimento & desenvolvimento
5.
Proc Biol Sci ; 286(1897): 20182477, 2019 02 27.
Artigo em Inglês | MEDLINE | ID: mdl-30963833

RESUMO

Biological invasions are on the rise globally. To reduce future invasions, it is imperative to determine the naturalization potential of species. Until now, screening approaches have relied largely on species-specific functional feature data. Such information is, however, time-consuming and expensive to collect, thwarting the screening of large numbers of potential invaders. We propose to resolve such data limitations by developing indicators of establishment success of alien species that can be readily derived from open-access databases. These indicators describe key features of successfully established aliens, including estimates of potential range size, niche overlap with human-disturbed environments, and proxies of species traits related to their palaeoinvasions and local dominance capacities. We demonstrate the utility of this new approach by applying it to two large and highly invasive plant groups: Australian acacias and eucalypts. Our results show that these indicators robustly predict establishment successes and failures in each clade independently, and that they can cross-predict establishment in these two clades. Interestingly, the indicator identified as most important was species potential range size on Earth, a variable too rarely considered as a predictor. By successfully identifying key features that predispose Australian plants to naturalize, we provide an objective and cost-effective protocol for flagging high-risk introductions.


Assuntos
Ecossistema , Espécies Introduzidas , Traços de História de Vida , Dispersão Vegetal , Fenômenos Fisiológicos Vegetais , Acacia/fisiologia , Austrália , Eucalyptus/fisiologia , Dinâmica Populacional , Especificidade da Espécie
6.
Tree Physiol ; 39(6): 910-924, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30865274

RESUMO

Drought-induced tree mortality alters forest structure and function, yet our ability to predict when and how different species die during drought remains limited. Here, we explore how stomatal control and drought tolerance traits influence the duration of drought stress leading to critical levels of hydraulic failure. We examined the growth and physiological responses of four woody plant species (three angiosperms and one conifer) representing a range of water-use and drought tolerance traits over the course of two controlled drought-recovery cycles followed by an extended dry-down. At the end of the final dry-down phase, we measured changes in biomass ratios and leaf carbohydrates. During the first and second drought phases, plants of all species closed their stomata in response to decreasing water potential, but only the conifer species avoided water potentials associated with xylem embolism as a result of early stomatal closure relative to thresholds of hydraulic dysfunction. The time it took plants to reach critical levels of water stress during the final dry-down was similar among the angiosperms (ranging from 39 to 57 days to stemP88) and longer in the conifer (156 days to stemP50). Plant dry-down time was influenced by a number of factors including species stomatal-hydraulic safety margin (gsP90 - stemP50), as well as leaf succulence and minimum stomatal conductance. Leaf carbohydrate reserves (starch) were not depleted at the end of the final dry-down in any species, irrespective of the duration of drought. These findings highlight the need to consider multiple structural and functional traits when predicting the timing of hydraulic failure in plants.


Assuntos
Secas , Magnoliopsida/fisiologia , Pinus/fisiologia , Árvores/fisiologia , Eucalyptus/fisiologia , Folhas de Planta/fisiologia , Caules de Planta/fisiologia , Estômatos de Plantas/fisiologia , Estresse Fisiológico , Árvores/crescimento & desenvolvimento
7.
Tree Physiol ; 39(6): 1061-1070, 2019 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-30865277

RESUMO

Transient thermal dissipation (TTD) systems provide a simple way to measure xylem sap flow with dual or single Granier-type probe, which gives lower energy consumption and higher accuracy due to its lessor sensitivity to thermal interferences. A new system, TTD heat within 5 min (TTD5), proposed on the reduction of the heating duration. This evolution captured interest through decreased energy consumption and increased temporal resolution. Within our study, the first objective was to test and calibrate this new system with a single probe for young rubber tree - Hevea brasiliensis. The second objective was to explore the sources of variability in calibration such as species, individual cut-stems and probe-wood contact. The complementary species consisted of two diffuse-porous species (mango tree - Mangifera indica, eucalyptus tree - Eucalyptus camaldulensis) and one ring-porous species (teak tree - Tectonia grandis). Twenty-eight response curves were assessed over a large range of flux densities from 0.5 to 10 l dm-2 h-1. The incremental rise of temperature from 30 to 300 s (T300-30) after commencement of heating was sensitive to flux density over the complete range. Compared with the full signal at 300 s, the incremental signal markedly reduced the variability between response curves within species and between species. Moreover, a new index K2, defined as (T0 - Tu)/T0, normalized the responses between 0 and 1. However, the responses had a non-linear trend above 5 l dm-2 h-1. Within diffuse-porous wood type, the species did not differ in calibration, whereas the ring-porous species was markedly different. A sigmoid function provided the best fit for the diffuse-porous species. Individual stems were identified as the main source of within-species variability in calibration. The normalizing K2 index removed the influence of probe-wood contacts, controlled through drilling difference; however, there was still an effect of individual stems interacting with flux density (P = 0.019). Replications of cut-stems and response curves are necessary to assess a reliable averaged calibration. In conclusion, the applicability of the TTD5 system with a single probe has been confirmed and several sources of variability in calibration have been evaluated.


Assuntos
Botânica/métodos , Transpiração Vegetal/fisiologia , Árvores/fisiologia , Xilema/fisiologia , Botânica/instrumentação , Calibragem , Eucalyptus/fisiologia , Hevea/fisiologia , Lamiaceae/fisiologia , Mangifera/fisiologia , Especificidade da Espécie , Temperatura Ambiente , Madeira/fisiologia
8.
Glob Chang Biol ; 25(5): 1665-1684, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30746837

RESUMO

Understanding forest tree responses to climate warming and heatwaves is important for predicting changes in tree species diversity, forest C uptake, and vegetation-climate interactions. Yet, tree species differences in heatwave tolerance and their plasticity to growth temperature remain poorly understood. In this study, populations of four Eucalyptus species, two with large range sizes and two with comparatively small range sizes, were grown under two temperature treatments (cool and warm) before being exposed to an equivalent experimental heatwave. We tested whether the species with large and small range sizes differed in heatwave tolerance, and whether trees grown under warmer temperatures were more tolerant of heatwave conditions than trees grown under cooler temperatures. Visible heatwave damage was more common and severe in the species with small rather than large range sizes. In general, species that showed less tissue damage maintained higher stomatal conductance, lower leaf temperatures, larger increases in isoprene emissions, and less photosynthetic inhibition than species that showed more damage. Species exhibiting more severe visible damage had larger increases in heat shock proteins (HSPs) and respiratory thermotolerance (Tmax ). Thus, across species, increases in HSPs and Tmax were positively correlated, but inversely related to increases in isoprene emissions. Integration of leaf gas-exchange, isoprene emissions, proteomics, and respiratory thermotolerance measurements provided new insight into mechanisms underlying variability in tree species heatwave tolerance. Importantly, warm-grown seedlings were, surprisingly, more susceptible to heatwave damage than cool-grown seedlings, which could be associated with reduced enzyme concentrations in leaves. We conclude that species with restricted range sizes, along with trees growing under climate warming, may be more vulnerable to heatwaves of the future.


Assuntos
Mudança Climática , Eucalyptus/fisiologia , Resposta ao Choque Térmico/fisiologia , Temperatura Ambiente , Eucalyptus/genética , Eucalyptus/crescimento & desenvolvimento , Eucalyptus/metabolismo , Florestas , Fotossíntese/fisiologia , Dispersão Vegetal , Folhas de Planta/fisiologia , Especificidade da Espécie , Termotolerância
9.
Tree Physiol ; 39(4): 679-693, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30597089

RESUMO

We assessed the effects of heater wattage on sap flux estimates from heat dissipation sensors and generated calibrated equations for 1-year-old Eucalyptus grandis Hill ex Maiden trees. We used a total of eight trees ranging from 3 to 6 cm in diameter. Our calibration experiment was performed with a modified tree-cut approach, which allowed us to estimate gravimetric water use manually weighing 20 l buckets every 15 min while sap flux was monitored on each tree. Our results indicate that changes the current supplied to the heaters from 0.15 to 0.25 W does not significantly influence sap flux estimates, as long as the maximum temperature (Tmax) is properly determined for each period when wattage is different, and natural temperature gradients are corrected. Using the original parameters developed for this method, sap flux density and sap flow had an average underestimation of 53%, which according to our analysis had a reduced but relevant correlation with tree diameter (R2 = 0.3, linear regression). These results may allow researchers to supply different currents to heat dissipation sensors to increase sensitivity or to reduce power consumption. They also provide evidence in favor of the correction and use of raw data collected when unwanted changes in wattage occur. The relationship observed between estimation error and tree diameter, while not strongly significant, suggests that diameter plays an important role in the estimation errors that has not been previously considered, and requires further research.


Assuntos
Eucalyptus/fisiologia , Transpiração Vegetal/fisiologia , Água/fisiologia , Transporte Biológico , Calibragem , Temperatura Alta , Caules de Planta/fisiologia , Árvores
10.
Plant Biotechnol J ; 17(4): 801-811, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30230168

RESUMO

The breeding of plantation forestry trees for the possible afforestation of marginal land would be one approach to addressing global warming issues. Here, we developed novel transgenic Eucalyptus trees (Eucalyptus camaldulensis Dehnh.) harbouring an RNA-Binding-Protein (McRBP) gene derived from a halophyte plant, common ice plant (Mesembryanthemum crystallinum L.). We conducted screened-house trials of the transgenic Eucalyptus using two different stringency salinity stress conditions to evaluate the plants' acute and chronic salt stress tolerances. Treatment with 400 mM NaCl, as the high-stringency salinity stress, resulted in soil electrical conductivity (EC) levels >20 mS/cm within 4 weeks. With the 400 mM NaCl treatment, >70% of the transgenic plants were intact, whereas >40% of the non-transgenic plants were withered. Treatment with 70 mM NaCl, as the moderate-stringency salinity stress, resulted in soil EC levels of approx. 9 mS/cm after 2 months, and these salinity levels were maintained for the next 4 months. All plants regardless of transgenic or non-transgenic status survived the 70 mM NaCl treatment, but after 6-month treatment the transgenic plants showed significantly higher growth and quantum yield of photosynthesis levels compared to the non-transgenic plants. In addition, the salt accumulation in the leaves of the transgenic plants was 30% lower than that of non-transgenic plants after 15-week moderate salt stress treatment. There results suggest that McRBP expression in the transgenic Eucalyptus enhances their salt tolerance both acutely and chronically.


Assuntos
Eucalyptus/genética , Mesembryanthemum/genética , Proteínas de Ligação a RNA/metabolismo , Embaralhamento de DNA , Eucalyptus/fisiologia , Fotossíntese , Folhas de Planta/genética , Folhas de Planta/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Proteínas de Ligação a RNA/genética , Salinidade , Tolerância ao Sal , Plantas Tolerantes a Sal , Cloreto de Sódio/efeitos adversos , Árvores
11.
Sci Total Environ ; 655: 1457-1467, 2019 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-30577137

RESUMO

Sewage sludge (SS) reuse in forest plantation as soil fertilizer/amendment has tremendously increased in recent years. However, SS may have high concentrations of potentially toxic elements (PTE), representing a potential risk for soil and the whole ecosystem. This paper was aimed to assess the toxicity of PTE in unfertile tropical soils amended with SS in a commercial Eucalyptus plantation, with an integrated multiple approaches combining: i) the use of a battery of bioassays (Daphnia magna, Pseudokcrichirella subcapitata, Lactuca sativa, and Allium cepa); and ii) the evaluation of some PTE (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) and their availability into the pedoenvironment. Differences in total and available PTE between SS doses and time of treatments were evaluated using ANOVA; correlations between PTE and bioassays by a sparse partial robust M-regression (SPRM), while multiple correlations among parameters were performed by principal factor analysis (PFA). Results show that PTE contents in soils tended to increase with SS application doses. However this cannot be assumed as a general rule since in all the investigated treatments the PTE concentrations were consistently below both soil natural background concentrations and quality reference values. Bioassays showed a generalized low eco- and genotoxicity of SS with an increase in toxicity at increasing SS doses but with a clear decreasing trend as time went by. A. cepa was the most sensitive bioassay followed by P. subcapitata > D. magna > L. sativa. Overall, the results indicate that in realistic open field conditions SS risk may be lower than expected due to dynamic decrease in PTE toxicity with time after application. This study has an important implication that open-field trials should be strongly encouraged for evaluating environmental risk of SS application in forestry.


Assuntos
Eucalyptus/efeitos dos fármacos , Fertilizantes/análise , Esgotos/efeitos adversos , Poluentes do Solo/toxicidade , Eucalyptus/crescimento & desenvolvimento , Eucalyptus/fisiologia , Agricultura Florestal , Solo/química
12.
Tree Physiol ; 38(11): 1623-1639, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30496539

RESUMO

Previous knowledge suggested the involvement of specific pathways/proteins that could be identified as potential molecular indicators linked to enhanced drought tolerance in Eucalyptus globulus. Here, we looked for specific variations in key transcripts of two Eucalyptus globulus clones (AL-18 and AL-13) exposed to water deficit and rehydration with two main goals: (i) to check if and how transcripts potentially associated with stress response and protection are modulated in a controlled experiment; and (ii) to verify if the transcript response is robust in a field case study. Our results showed that the controlled experiment induced a severe acute stress that resulted in a strong realignment of gene expression resulting from an overwhelming of physiological adjustments to water limitation. A number of transcripts exhibited altered abundance after the acute water stress: reduction of RuBisCO activase and mitochondrial glycine cleavage system H protein, and increase of isoflavone reductase. Malate dehydrogenase, catalase, dehydration response element B1A and potassium channel GORK showed a different abundance pattern in each clone. The stress in the field was more moderate and chronic and the plants were able to deal with the stress primarily through physiological adjustments resulting in much smaller changes in gene expression. The transcripts of clone AL-18 showed few alterations between irrigated and non-irrigated plants throughout the experiment, while the transcript changes found in clone AL-13 highlighted the impact of early rewatering rather than growing under extended drought typical of a Mediterranean summer. Although a few concurrent responses were found, the results obtained in the field study draw a very distinct picture when compared with the controlled experiment.


Assuntos
Aclimatação/genética , Secas , Eucalyptus/fisiologia , Transcrição Genética/fisiologia , Dessecação , Eucalyptus/genética , Perfilação da Expressão Gênica , Portugal , Reação em Cadeia da Polimerase em Tempo Real , Estresse Fisiológico/genética , Fatores de Tempo
13.
J Hered ; 109(7): 802-810, 2018 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-30285150

RESUMO

Open-pollinated (OP) mating is frequently used in forest tree breeding due to the relative temporal and financial efficiency of the approach. The trade-off is the lower precision of the estimated genetic parameters. Pedigree/sib-ship reconstruction has been proven as a tool to correct and complete pedigree information and to improve the precision of genetic parameter estimates. Our study analyzed an advanced generation Eucalyptus population from an OP breeding program using single-step genetic evaluation. The relationship matrix inferred from sib-ship reconstruction was used to rescale the marker-based relationship matrix (G matrix). This was compared with a second scenario that used rescaling based on the documented pedigree. The proposed single-step model performed better with respect to both model fit and the theoretical accuracy of breeding values. We found that the prediction accuracy was superior when using the pedigree information only when compared with using a combination of the pedigree and genomic information. This pattern appeared to be mainly a result of accumulated unrecognized relatedness over several breeding cycles, resulting in breeding values being shrunk toward the population mean. Using biased, pedigree-based breeding values as the base with which to correlate predicted GEBVs, resulted in the underestimation of prediction accuracies. Using breeding values estimated on the basis of sib-ship reconstruction resulted in increased prediction accuracies of the genotyped individuals. Therefore, selection of the correct base for estimation of prediction accuracy is critical. The beneficial impact of sib-ship reconstruction using G matrix rescaling was profound, especially in traits with inbreeding depression, such as stem diameter.


Assuntos
Cruzamento/métodos , Eucalyptus/genética , Eucalyptus/fisiologia , Genes de Plantas , Polinização , Marcadores Genéticos
14.
Plant Cell Environ ; 41(12): 2869-2881, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30106477

RESUMO

The ability to resist hydraulic dysfunction in leaves, stems, and roots strongly influences whether plants survive and recover from drought. However, the coordination of hydraulic function among different organs within species and their links to gas exchange during drought and recovery remains understudied. Here, we examine the interaction between gas exchange and hydraulic function in the leaves, stems, and roots of three semiarid evergreen species exposed to a cycle of severe water stress (associated with substantial cavitation) and recovery. In all species, stomatal closure occurred at water potentials well before 50% loss of stem hydraulic conductance, while in two species, leaves and/or roots were more vulnerable than stems. Following soil rewetting, leaf-level photosynthesis (Anet ) returned to prestress levels within 2-4 weeks, whereas stomatal conductance and canopy transpiration were slower to recover. The recovery of Anet was decoupled from the recovery of leaf, stem, and root hydraulics, which remained impaired throughout the recovery period. Our results suggest that in addition to high embolism resistance, early stomatal closure and hydraulic vulnerability segmentation confers drought tolerance in these arid zone species. The lack of substantial embolism refilling within all major organs suggests that vulnerability of the vascular system to drought-induced dysfunction is a defining trait for predicting postdrought recovery.


Assuntos
Acacia/fisiologia , Eucalyptus/fisiologia , Folhas de Planta/fisiologia , Raízes de Plantas/fisiologia , Caules de Planta/fisiologia , Transpiração Vegetal , Água/metabolismo , Acacia/metabolismo , Desidratação , Eucalyptus/metabolismo , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Caules de Planta/metabolismo , Transpiração Vegetal/fisiologia
15.
Gene ; 678: 38-48, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30077764

RESUMO

The WRKY transcription factors, a large family of proteins in plants, are involved in multiple developmental and biological processes including response to phytohormones and abiotic stress. However, little information is available regarding the WRKY family in Eucalyptus, which has been the most widely planted hardwood trees in tropical and subtropical areas. In this study, a total of 79 WRKY genes (named as EgrWRKY1-79) were identified from the Eucalyptus grandis genome and classified into three main groups according to the phylogenetic analysis, which was further supported by their gene structure and conserved motifs. Of which, 28 EgrWRKYs were involved in tandem duplication but none for segmental duplication, indicating that tandem duplication was the main cause for the expansion of WRKY gene family in E. grandis. Subsequently, expression profiles of EgrWRKY genes in eight different tissues and in response to treatments of three hormones (SA, JA, and BR) and two abiotic stresses (salt and cold) were analyzed. The results revealed that the EgrWRKY genes had differential expression in their transcript abundance and they were differentially expressed in response to plant hormones and salt and cold stresses, suggesting their contributions to plant developmental processes as well as abiotic stresses with the involvement of hormone signaling transduction. Taken together, these findings will increase our understanding of EgrWRKY gene family involved in abiotic stresses and hormone signaling transduction, and also will provide some stress-responsive candidate EgrWRKY genes for further characterization of their functions in Eucalyptus.


Assuntos
Eucalyptus/genética , Perfilação da Expressão Gênica/métodos , Reguladores de Crescimento de Planta/farmacologia , Fatores de Transcrição/genética , Cromossomos de Plantas/genética , Eucalyptus/fisiologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Genoma de Planta , Família Multigênica , Filogenia , Proteínas de Plantas/genética , Estresse Fisiológico , Distribuição Tecidual
16.
J Chem Ecol ; 44(7-8): 658-670, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30039208

RESUMO

In the worldwide search for new strategies in sustainable weed management, the use of allelopathic plants incorporated into the soil as green manure can help control weeds by releasing allelochemicals into the environment. In previous experiments, Eucalyptus globulus leaves incorporated into the soil as green manure were shown to have a notable potential for weed control. But, 'what was exactly happening at chemical level?' and 'which were the compounds potentially responsible for the phytotoxic effects observed during those greenhouse assays?' In the present study, in-vitro phytotoxicity bioassays and chemical analysis of eucalyptus leaves were carried out in order to explore the relationship between the temporal phytotoxic effects and the dynamics of chemical composition. For that, eucalyptus leaves were removed from soil at different sampling times during 30 days and analyzed for phenolic and volatile organic compounds (VOCs) by HPLC and HS-SPME/GC-MS, respectively. The phytotoxic potential of the aqueous extract and the volatile fraction was tested on the germination and early growth of Lactuca sativa. Eucalyptus leaves incorporated into the soil as green manure showed a continuous release of different phenolic and volatile compounds during a 30-day period of decomposition. Both fractions had phytotoxic effects during the time assayed; however, the target process of phytotoxicity was different: phenolic compounds being the factor causing germination inhibition and VOCs responsible for growth reduction. The dynamics of release of this cocktail of allelochemicals into the soil environment may be the responsible for the phytotoxicity observed in our previous works.


Assuntos
Eucalyptus/fisiologia , Feromônios/metabolismo , Folhas de Planta/fisiologia , Alelopatia , Eucalyptus/química , Germinação/efeitos dos fármacos , Alface/efeitos dos fármacos , Alface/crescimento & desenvolvimento , Fenóis/análise , Fenóis/metabolismo , Feromônios/análise , Feromônios/toxicidade , Folhas de Planta/química , Solo/química , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/metabolismo , Compostos Orgânicos Voláteis/toxicidade , Controle de Plantas Daninhas/métodos
17.
Tree Physiol ; 38(9): 1286-1301, 2018 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-29741732

RESUMO

Intraspecific variation in biomass production responses to elevated atmospheric carbon dioxide (eCO2) could influence tree species' ecological and evolutionary responses to climate change. However, the physiological mechanisms underlying genotypic variation in responsiveness to eCO2 remain poorly understood. In this study, we grew 17 Eucalyptus camaldulensis Dehnh. subsp. camaldulensis genotypes (representing provenances from four different climates) under ambient atmospheric CO2 and eCO2. We tested whether genotype leaf-scale photosynthetic and whole-tree carbon (C) allocation responses to eCO2 were predictive of genotype biomass production responses to eCO2. Averaged across genotypes, growth at eCO2 increased in situ leaf net photosynthesis (Anet) (29%) and leaf starch concentrations (37%). Growth at eCO2 reduced the maximum carboxylation capacity of Rubisco (-4%) and leaf nitrogen per unit area (Narea, -6%), but Narea calculated on a total non-structural carbohydrate-free basis was similar between treatments. Growth at eCO2 also increased biomass production and altered C allocation by reducing leaf area ratio (-11%) and stem mass fraction (SMF, -9%), and increasing leaf mass area (18%) and leaf mass fraction (5%). Overall, we found few significant CO2 × provenance or CO2 × genotype (within provenance) interactions. However, genotypes that showed the largest increases in total dry mass at eCO2 had larger increases in root mass fraction (with larger decreases in SMF) and photosynthetic nitrogen-use efficiency (PNUE) with CO2 enrichment. These results indicate that genetic differences in PNUE and carbon sink utilization (in roots) are both important predictors of tree productivity responsiveness to eCO2.


Assuntos
Dióxido de Carbono , Carbono/metabolismo , Eucalyptus/fisiologia , Fotossíntese/genética , Folhas de Planta/fisiologia , Austrália , Biomassa , Eucalyptus/genética , Genótipo , Nitrogênio/metabolismo , Fotossíntese/fisiologia , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Ribulose-Bifosfato Carboxilase/metabolismo , Árvores/crescimento & desenvolvimento , Árvores/fisiologia
18.
Ann Bot ; 122(1): 181-194, 2018 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-29788049

RESUMO

Background and Aims: Evolutionary change in developmental trajectories (heterochrony) is a major mechanism of adaptation in plants and animals. However, there are few detailed studies of the variation in the timing of developmental events among wild populations. We here aimed to identify the climatic drivers and measure selection shaping a genetic-based developmental cline among populations of an endemic tree species complex on the island of Tasmania. Methods: Seed lots from 38 native provenances encompassing the clinal transition from the heteroblastic Eucalyptus tenuiramis to the homoblastic Eucalyptus risdonii were grown in a common-garden field trial in southern Tasmania for 20 years. We used 27 climatic variables to model the provenance variation in vegetative juvenility as assessed at age 5 years. A phenotypic selection analysis was used to measure the fitness consequences of variation in vegetative juvenility based on its impact on the survival and reproductive capacity of survivors at age 20 years. Key Results: Significant provenance divergence in vegetative juvenility was shown to be associated with home-site aridity, with the retention of juvenile foliage increasing with increasing aridity. Our results indicated that climate change may lead to different directions of selection across the geographic range of the complex, and in our mesic field site demonstrated that total directional selection within phenotypically variable provenances was in favour of reduced vegetative juvenility. Conclusions: We provide evidence that heteroblasty is adaptive and argue that, in assessing the impacts of rapid global change, developmental plasticity and heterochrony are underappreciated processes which can contribute to populations of long-lived organisms, such as trees, persisting and ultimately adapting to environmental change.


Assuntos
Evolução Biológica , Eucalyptus/genética , Adaptação Fisiológica , Mudança Climática , Eucalyptus/fisiologia , Florestas , Fenótipo , Sementes/genética , Sementes/fisiologia , Tasmânia , Árvores
19.
Glob Chang Biol ; 24(9): 4293-4303, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29758588

RESUMO

Analysis of growth and biomass turnover in natural forests of Eucalyptus regnans, the world's tallest angiosperm, reveals it is also the world's most productive forest type, with fire disturbance an important mediator of net primary productivity (NPP). A comprehensive empirical database was used to calculate the averaged temporal pattern of NPP from regeneration to 250 years age. NPP peaks at 23.1 ± 3.8 (95% interquantile range) Mg C ha-1  year-1 at age 14 years, and declines gradually to about 9.2 ± 0.8 Mg C ha-1  year-1 at 130 years, with an average NPP over 250 years of 11.4 ± 1.1 Mg C ha-1  year-1 , a value similar to the most productive temperate and tropical forests around the world. We then applied the age-class distribution of E. regnans resulting from relatively recent historical fires to estimate current NPP for the forest estate. Values of NPP were 40% higher (13 Mg C ha-1  year-1 ) than if forests were assumed to be at maturity (9.2 Mg C ha-1  year-1 ). The empirically derived NPP time series for the E. regnans estate was then compared against predictions from 21 global circulation models, showing that none of them had the capacity to simulate a post-disturbance peak in NPP, as found in E. regnans. The potential importance of disturbance impacts on NPP was further tested by applying a similar approach to the temperate forests of conterminous United States and of China. Allowing for the effects of disturbance, NPP summed across both regions was on average 11% (or 194 Tg C/year) greater than if all forests were assumed to be in a mature state. The results illustrate the importance of accounting for past disturbance history and growth stage when estimating forest primary productivity, with implications for carbon balance modelling at local to global scales.


Assuntos
Ciclo do Carbono , Eucalyptus/fisiologia , Florestas , Árvores/crescimento & desenvolvimento , Austrália , China , Eucalyptus/crescimento & desenvolvimento , Estados Unidos
20.
Tree Physiol ; 38(8): 1193-1199, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29757423

RESUMO

Manipulative experiments have suggested that embolism-induced hydraulic impairment underpins widespread tree mortality during extreme drought, yet in situ evidence is rare. One month after drought-induced leaf and branch dieback was observed in field populations of Eucalyptus piperita Sm. in the Blue Mountains (Australia), we measured the level of native stem embolism and characterized the extent of leaf death in co-occurring dieback and healthy (non-dieback) trees. We found that canopy dieback-affected trees showed significantly higher levels of native embolism (26%) in tertiary order branchlets than healthy trees (11%). Furthermore, there was a significant positive correlation (R2 = 0.51) between the level of leaf death and the level of native embolism recorded in branchlets from dieback-affected trees. This retrospective study suggests that hydraulic failure was the primary mechanism of leaf and branch dieback in response to a natural drought event in the field. It also suggests that post-drought embolism refilling is minimal or absent in this species of eucalypt.


Assuntos
Secas , Eucalyptus/fisiologia , Xilema/fisiologia , Longevidade , New South Wales , Folhas de Planta/fisiologia , Caules de Planta/fisiologia
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