A holística do metabolismo do carbono no processo de respiração: as relações entre o efluxo de CO 2 e as variações de temperatura nas árvores de uma floresta de Terra Firme na Amazônia Central

The real carbon sink represented by Amazon forest and the autotrophic feedback respiration in trees facing the climate change are emergency questions to be answeredand it can help to better characterize the carbon balance in tropical forests. It is well known that plants as primary producer presents low efficiency rates of CO 2 assimilation via photosynthesis. Considering this, a large amount of carbon (approximately 70%) can be lost to respiration processes and it can represent a potential carbon loss that is reemitted as CO 2 to the atmosphere. It is clearly known and well accepted at plants physiology area of knowledge that trunks significantly contribute for the plants CO 2 emissions, in rates that can be greater than the leaves emissions by unit area. Considering this, the aim of this study was to provide information about the intern transport of CO 2 in plants and the routes of this carbon emitted by respiration. To conduct this research three trees were monitored at the “terra firme” forest at the central Amazon, by collecting data of: stem CO 2 efflux (E A ), stem temperature, crown temperature and sap velocity. As results, evidences of the control that temperature shows by mediating the inner water transport, and consequently on E A were found. It was also possible to show the differences between day and night time for all the measured variables obtained for all the trees that composed this study. Mainly, the contribution of this study is a holistic aspect in what concerns the E A that is an important component of the carbon cycle in plants. The interactions and also the mechanisms that controls the respiration processes which doesn’t works separately, could be characterized by the importance that temperature shows to the inner water transport and the connections of this mechanism with the respiration processes at the trees.O esclarecimento da real capacidade de sequestro de CO 2 pelas florestas e os feedbacks da respiração das plantas frente à mudança no clima global são de suma importância para tornar conhecido o balanço de carbono nas florestas tropicais. Sabe-se que as plantas, enquanto produtoras primárias, apresentam baixas taxas de aproveitamento de CO 2 na assimilação via fotossíntese para a formação de folhas, galhos, troncos e raízes. Este baixo aproveitamento reflete em estimativas de que até 70% do total de CO 2 absorvido na fotossíntese não é assimilado na formação ou na manutenção de tecidos celulares e,portanto, é reemitido pelo processo de respiração. Na área de conhecimento de fisiologia vegetal é esclarecido e aceito que o tronco das árvores contribui significativamente para o total de CO 2 emitido pelas plantas em taxas que, por unidade de área, podem inclusive superar a respiração nas folhas. Dessa forma, este estudo teve como finalidade promover o melhor entendimento sobre o transporte interno do CO 2 bem como os possíveis destinos desse carbono na fisiologia das plantas. Para tanto, foram monitorados em três árvores de floresta de terra firme na Amazônia central, os seguintes parâmetros: efluxo de CO 2 na superfície do tronco (E A ), temperatura do tronco, temperatura da copa e a velocidade de transporte de seiva inorgânica. Como resultado, foram encontradas evidências da importância que as variações de temperatura na copa exercem sobre a regulação da variável velocidade de transporte de seiva, o que consequentemente implica em variações no E A . Também foi possível demonstrar as diferenças entre dia e noite que ocorrem para as variáveis que foram coletadas em todas as árvores que compuseram o estudo. Sobretudo, os resultados gerados no presente estudo contribuem para promover uma abordagem holística do ciclo do carbono, em se tratando do produto do processo de respiração, relacionado à dinâmica da água nas árvores estudadas. Dessa forma, as interações e mecanismos que regulam os processos biológicos que não funcionam de forma isolada e compartimentalizada foram descritas sob a perspectiva das variações simultâneas da temperatura da copa das árvores e da velocidade de transporte de seiva no xilema produzindo efeito na regulação dos destinos do CO 2 resultante da respiração celular

Demonstration of a strict molecular oxygen requirement of yellow latex oxidation in the central Amazon canopy tree muiratinga (Maquira sclerophylla (Ducke) C.C. Berg)

Plant-derived latex is widely used in rubber production and plays important roles in ecological processes in the tropics. Although it is known that latex oxidation from the commercially important tree Hevea brasiliensis, results in latex browning, little is known about latex oxidation in highly diverse tropical ecosystems. Here we show that upon physical trunk damage, yellow latex released from the canopy tree Muiratinga (Maquira sclerophylla (Ducke) C.C. Berg) is rapidly and extensively oxidized to a black resin in the presence of air within 15-30 min. In a nitrogen atmosphere, latex oxidation was inhibited, but was immediately activated upon exposure to air. The results suggest the occurrence of O2-dependent oxidative enzymes including polyphenol oxidase (PPO) within the latex of Muiratinga and supports previous findings of a key role of oxidation during latex coagulation. © 2018 Secretaria Regional do Rio de Janeiro da Sociedade Brasileira de Quimica.All right reserved

Volatile monoterpene ‘fingerprints’ of resinous Protium tree species in the Amazon rainforest

Volatile terpenoid resins represent a diverse group of plant defense chemicals involved in defense against herbivory, abiotic stress, and communication. However, their composition in tropical forests remains poorly characterized. As a part of tree identification, the ‘smell’ of damaged trunks is widely used, but is highly subjective. Here, we analyzed trunk volatile monoterpene emissions from 15 species of the genus Protium in the central Amazon. By normalizing the abundances of 28 monoterpenes, 9 monoterpene ‘fingerprint’ patterns emerged, characterized by a distinct dominant monoterpene. While 4 of the ‘fingerprint’ patterns were composed of multiple species, 5 were composed of a single species. Moreover, among individuals of the same species, 6 species had a single ‘fingerprint’ pattern, while 9 species had two or more ‘fingerprint’ patterns among individuals. A comparison of ‘fingerprints’ between 2015 and 2017 from 15 individuals generally showed excellent agreement, demonstrating a strong dependence on species identity, but not time of collection. The results are consistent with a previous study that found multiple divergent copies of monoterpene synthase enzymes in Protium. We conclude that the monoterpene ‘fingerprint’ database has important implications for constraining Protium species identification and phylogenetic relationships and enhancing understanding of physiological and ecological functions of resins and their potential commercial applications. © 2019 The Author

Below versus above ground plant sources of abscisic acid (ABA) at the heart of tropical forest response to warming

Warming surface temperatures and increasing frequency and duration of widespread droughts threaten the health of natural forests and agricultural crops. High temperatures (HT) and intense droughts can lead to the excessive plant water loss and the accumulation of reactive oxygen species (ROS) resulting in extensive physical and oxidative damage to sensitive plant components including photosynthetic membranes. ROS signaling is tightly integrated with signaling mechanisms of the potent phytohormone abscisic acid (ABA), which stimulates stomatal closure leading to a reduction in transpiration and net photosynthesis, alters hydraulic conductivities, and activates defense gene expression including antioxidant systems. While generally assumed to be produced in roots and transported to shoots following drought stress, recent evidence suggests that a large fraction of plant ABA is produced in leaves via the isoprenoid pathway. Thus, through stomatal regulation and stress signaling which alters water and carbon fluxes, we highlight the fact that ABA lies at the heart of the Carbon-Water-ROS Nexus of plant response to HT and drought stress. We discuss the current state of knowledge of ABA biosynthesis, transport, and degradation and the role of ABA and other isoprenoids in the oxidative stress response. We discuss potential variations in ABA production and stomatal sensitivity among different plant functional types including isohydric/anisohydric and pioneer/climax tree species. We describe experiments that would demonstrate the possibility of a direct energetic and carbon link between leaf ABA biosynthesis and photosynthesis, and discuss the potential for a positive feedback between leaf warming and enhanced ABA production together with reduced stomatal conductance and transpiration. Finally, we propose a new modeling framework to capture these interactions. We conclude by discussing the importance of ABA in diverse tropical ecosystems through increases in the thermotolerance of photosynthesis to drought and heat stress, and the global importance of these mechanisms to carbon and water cycling under climate change scenarios. © 2018 by the authors. Licensee MDPI, Basel, Switzerland

Below versus above Ground Plant Sources of Abscisic Acid (ABA) at the Heart of Tropical Forest Response to Warming.

Warming surface temperatures and increasing frequency and duration of widespread droughts threaten the health of natural forests and agricultural crops. High temperatures (HT) and intense droughts can lead to the excessive plant water loss and the accumulation of reactive oxygen species (ROS) resulting in extensive physical and oxidative damage to sensitive plant components including photosynthetic membranes. ROS signaling is tightly integrated with signaling mechanisms of the potent phytohormone abscisic acid (ABA), which stimulates stomatal closure leading to a reduction in transpiration and net photosynthesis, alters hydraulic conductivities, and activates defense gene expression including antioxidant systems. While generally assumed to be produced in roots and transported to shoots following drought stress, recent evidence suggests that a large fraction of plant ABA is produced in leaves via the isoprenoid pathway. Thus, through stomatal regulation and stress signaling which alters water and carbon fluxes, we highlight the fact that ABA lies at the heart of the Carbon-Water-ROS Nexus of plant response to HT and drought stress. We discuss the current state of knowledge of ABA biosynthesis, transport, and degradation and the role of ABA and other isoprenoids in the oxidative stress response. We discuss potential variations in ABA production and stomatal sensitivity among different plant functional types including isohydric/anisohydric and pioneer/climax tree species. We describe experiments that would demonstrate the possibility of a direct energetic and carbon link between leaf ABA biosynthesis and photosynthesis, and discuss the potential for a positive feedback between leaf warming and enhanced ABA production together with reduced stomatal conductance and transpiration. Finally, we propose a new modeling framework to capture these interactions. We conclude by discussing the importance of ABA in diverse tropical ecosystems through increases in the thermotolerance of photosynthesis to drought and heat stress, and the global importance of these mechanisms to carbon and water cycling under climate change scenarios

Below versus above Ground Plant Sources of Abscisic Acid (ABA) at the Heart of Tropical Forest Response to Warming.

Warming surface temperatures and increasing frequency and duration of widespread droughts threaten the health of natural forests and agricultural crops. High temperatures (HT) and intense droughts can lead to the excessive plant water loss and the accumulation of reactive oxygen species (ROS) resulting in extensive physical and oxidative damage to sensitive plant components including photosynthetic membranes. ROS signaling is tightly integrated with signaling mechanisms of the potent phytohormone abscisic acid (ABA), which stimulates stomatal closure leading to a reduction in transpiration and net photosynthesis, alters hydraulic conductivities, and activates defense gene expression including antioxidant systems. While generally assumed to be produced in roots and transported to shoots following drought stress, recent evidence suggests that a large fraction of plant ABA is produced in leaves via the isoprenoid pathway. Thus, through stomatal regulation and stress signaling which alters water and carbon fluxes, we highlight the fact that ABA lies at the heart of the Carbon-Water-ROS Nexus of plant response to HT and drought stress. We discuss the current state of knowledge of ABA biosynthesis, transport, and degradation and the role of ABA and other isoprenoids in the oxidative stress response. We discuss potential variations in ABA production and stomatal sensitivity among different plant functional types including isohydric/anisohydric and pioneer/climax tree species. We describe experiments that would demonstrate the possibility of a direct energetic and carbon link between leaf ABA biosynthesis and photosynthesis, and discuss the potential for a positive feedback between leaf warming and enhanced ABA production together with reduced stomatal conductance and transpiration. Finally, we propose a new modeling framework to capture these interactions. We conclude by discussing the importance of ABA in diverse tropical ecosystems through increases in the thermotolerance of photosynthesis to drought and heat stress, and the global importance of these mechanisms to carbon and water cycling under climate change scenarios

Protium Burm.f.

<i>2.4. Comparison of Protium monoterpene ‘fingerprints’ between individuals</i> <p> Of the 77 <i>Protium</i> individuals, we observed a consistency of <i>Protium</i> monoterpene ‘fingerprints’ that could be separated in two cases: a) similar monoterpene ‘fingerprints’ patterns between individuals of different species, b) similar monoterpene ‘fingerprints’ patterns between individuals of the same species. Graphical representations of example monoterpene ‘fingerprints’ showing consistency between individuals of different species (Figs. S2–S 4) and the same species (Figs. S5–S 6) is provided in the supporting information.</p> <p> As an example of similar patterns between individuals from different species, the comparison of the monoterpene ‘fingerprint’ from <i>P. calendulinum</i> species (Tree 1408) and that of <i>P. hebetatum</i> var. 1 (Tree 277C) showed a strong consistency of monoterpene patterns (Figs. S2a and S2d). Both ‘fingerprints’ presented the same dominant monoterpene (α-pinene) and similar relative abundance for other monoterpenes, including camphene, β-pinene, and <i>d</i> -limonene (MTPs 8, 12 and 18, respectively).</p> <p> In a second example, the monoterpene ‘fingerprint’ of a <i>P. paniculatum</i> var. <i>paniculatum</i> individual (Tree 1301) showed similarities with the ‘fingerprint’ of a second individual, from <i>P. paniculatum</i> var. <i>paniculatum</i> species (Tree 157), with α-phellandrene as the dominant monoterpene in both cases (compare Fig. S2b with S2e). There was also a good similarity between the relative abundances of the monoterpenes α-terpinene, β-phellandrene, γ-terpinene, α-terpinolene and isoterpinolene (MTPs 16, 19, 22, 24 and 25, respectively). Another interesting example showed that the ‘fingerprint’ of a <i>P. apiculatum</i> (Tree 464) had a good similarity with the ‘fingerprint’ of a <i>P. nitidifolium</i> (Tree 334D) individual, with <i>d</i> -limonene as the dominant monoterpene (compare Fig. S2c with S2f). More examples of monoterpene ‘fingerprints’ similarities for individuals from different species can be observed in Figs. S3 and S 4.</p> <p> A comparison analysis of monoterpene ‘fingerprints’ with similar patterns between individuals from the same species was also conducted. Monoterpene ‘fingerprints’ from two individuals of <i>P. hebetatum</i> var. 2 (Trees 661 and 724) showed a consistency of monoterpene patterns (compare Fig. S5a with S5d), with α-pinene as the dominant monoterpene. Furthermore, for both ‘fingerprints’, the monoterpenes β-pinene, α-phellandrene and α-terpinene were detected. For another two monoterpene ‘fingerprints’ (Trees 261 and 931B), also from <i>P. hebetatum</i> var. 2 species and with α-pinene as the dominant monoterpene, we can observe a consistency of monoterpenes occurrence and monoterpenes relative abundance (compare Fig. S5b with S5e). Other examples of similarities for ‘fingerprints’ from the same species are highlighted in Fig. S6 (a-f). In this figure, it is interesting to observe that four individuals from <i>P. paniculatum</i> var. <i>modestum</i> species presented strong similarities in their monoterpene ‘fingerprints’. For example, both Trees 1289 and 1295 (Figs. S6a and S6b) presented the occurrence of monoterpenes 3-carene, α-terpinene, β-phellandrene, cis-β-ocimene and γ-terpinene, with strong relative abundance similarities of these monoterpenes. For these four ‘fingerprints’ from the same species, the same dominant monoterpene (α-phellandrene) was observed, as well.</p>Published as part of <i>Piva, Luani R. de O., Jardine, Kolby J., Gimenez, Bruno O., Perdiz, Ricardo de Oliveira, Menezes, Valdiek S., Durgante, Flávia M., Cobello, Leticia O., Higuchi, Niro & Chambers, Jeffrey Q., 2019, Volatile monoterpene ' fingerprints' of resinous Protium tree species in the Amazon rainforest, pp. 61-70 in Phytochemistry 160</i> on pages 63-64, DOI: 10.1016/j.phytochem.2019.01.014, <a href="http://zenodo.org/record/10481082">http://zenodo.org/record/10481082</a&gt

Species-specific shifts in diurnal sap velocity dynamics and hysteretic behavior of ecophysiological variables during the 2015–2016 el niño event in the amazon forest

Current climate change scenarios indicate warmer temperatures and the potential for more extreme droughts in the tropics, such that a mechanistic understanding of the water cycle from individual trees to landscapes is needed to adequately predict future changes in forest structure and function. In this study, we contrasted physiological responses of tropical trees during a normal dry season with the extreme dry season due to the 2015–2016 El Niño-Southern Oscillation (ENSO) event. We quantified high resolution temporal dynamics of sap velocity (Vs), stomatal conductance (gs) and leaf water potential (ΨL) of multiple canopy trees, and their correlations with leaf temperature (Tleaf) and environmental conditions [direct solar radiation, air temperature (Tair) and vapor pressure deficit (VPD)]. The experiment leveraged canopy access towers to measure adjacent trees at the ZF2 and Tapajós tropical forest research (near the cities of Manaus and Santarém). The temporal difference between the peak of gs (late morning) and the peak of VPD (early afternoon) is one of the major regulators of sap velocity hysteresis patterns. Sap velocity displayed species-specific diurnal hysteresis patterns reflected by changes in Tleaf. In the morning, Tleaf and sap velocity displayed a sigmoidal relationship. In the afternoon, stomatal conductance declined as Tleaf approached a daily peak, allowing ΨL to begin recovery, while sap velocity declined with an exponential relationship with Tleaf. In Manaus, hysteresis indices of the variables Tleaf-Tair and ΨL-Tleaf were calculated for different species and a significant difference (p < 0.01, α = 0.05) was observed when the 2015 dry season (ENSO period) was compared with the 2017 dry season (“control scenario”). In some days during the 2015 ENSO event, Tleaf approached 40°C for all studied species and the differences between Tleaf and Tair reached as high at 8°C (average difference: 1.65 ± 1.07°C). Generally, Tleaf was higher than Tair during the middle morning to early afternoon, and lower than Tair during the early morning, late afternoon and night. Our results support the hypothesis that partial stomatal closure allows for a recovery in ΨL during the afternoon period giving an observed counterclockwise hysteresis pattern between ΨL and Tleaf. © 2019 Gimenez, Jardine, Higuchi, Negrón-Juárez, Sampaio-Filho, Cobello, Fontes, Dawson, Varadharajan, Christianson, Spanner, Araújo, Warren, Newman, Holm, Koven, McDowell and Chambers