abstract: Functional traits research has improved our understanding of how plants respond to their environments, identifying key trade-offs among traits. These studies primarily rely on correlative methods to infer trade-offs and often overlook traits that are difficult to measure (e.g., root traits, tissue senescence rates), limiting their predictive ability under novel conditions. I aimed to address these limitations and develop a better understanding of the trait space occupied by trees by integrating data and process models, spanning leaves to whole-trees, via modern statistical and computational methods. My first research chapter (Chapter 2) simultaneously fits a photosynthesis model to measurements of fluorescence and photosynthetic response curves, improving estimates of mesophyll conductance (gm) and other photosynthetic traits. I assessed how gm varies across environmental gradients and relates to other photosynthetic traits for 4 woody species in Arizona. I found that gm was lower at high aridity sites, varied little within a site, and is an important trait for obtaining accurate estimates of photosynthesis and related traits under dry conditions. Chapter 3 evaluates the importance of functional traits for whole-tree performance by fitting an individual-based model of tree growth and mortality to millions of measurements of tree heights and diameters to assess the theoretical trait space (TTS) of “healthy” North American trees. The TTS contained complicated, multi-variate structure indicative of potential trade-offs leading to successful growth. In Chapter 4, I applied an environmental filter (light stress) to the TTS, leading to simulated stand-level mortality rates up to 50%. Tree-level mortality was explained by 6 of the 32 traits explored, with the most important being radiation-use efficiency. The multidimentional space comprising these 6 traits differed in volume and location between trees that survived and died, indicating that selective mortality alters the TTS. / Dissertation/Thesis / Doctoral Dissertation Biology 2017

O aumento para demanda na produção de alimentos associado a possíveis alterações climáticas globais tem promovido um interesse renovado em pesquisas envolvendo o metabolismo fotossintético. Acredita-se que com o melhoramento fotossintético a produtividade das culturas aumente. Para se alcançar este objetivo, além do uso de práticas biotecnológicas, ainda são necessários estudos abordando as limitações intrisecas do processo fotossintético que possam contribuir com a identificação de alvos para a engenharia genética. Neste contexto, esta tese aborda perguntas especificas sobre a regulação da fotossíntese C4 pela nutrição nitrogenada, o deficit hídrico e a interação destes dois fatores. No primeiro capítulo experimental foi desenvolvido um estudo envolvendo os efeitos da nutrição nitrogenada na difusão interna de CO2. Foi observado que o conteúdo de nitrogênio (N) foliar é determinante para a condutância interna de CO2 (? 18O-gm). Um menor conteúdo de N induz reduções iniciais em ? 18O-gm devido menor atividade das enzimas carboxilativas. Conforme o conteúdo de N reduz em folhas mais velhas alterações na antomia passaram a contribuir com a regulação de ? 18O-gm. No segundo capítulo, foi explorada a variação genotipica de cana-de-açúcar quanto a parâmetros relacionados a fotossíntese e o nitrogênio foliar, envolvendo a eficiência de uso de nitrogênio fotossintética (PNUE) e índices de herdabilidade. A variabilidade dos materiais genéticos foi explicada principalmente pelos parâmetros de trocas gasosas que contribuíram com o agrupamento dos materiais em três grupos. A partir deste agrupamento é possível verificar as diferenças entre os materiais em reposta a nutrição nitrogenada. Além disto, parâmetros de trocas gasosas como a taxa de assimilação de CO2 e condutância estomática junto com PNUE apresentaram altos índices de herdabilidade no sentido restrito. Por fim, o terceiro capítulo investigou a regulação do metabolismo de assimilação de CO2 em resposta ao deficit hídrico em folhas de cana-de-açúcar e como o metabolismo de nitrogênio está envolvido neste processo. Diferentes fatores envolvidos na regulação negativa da fotossíntese foram identicados. Interesantemente, alterações nos componentes nitrogenados só contribuíram com a inibição metabólica na fase de estresse severo. Adicionalmente foi observado que a superação da inibição metabólica durante a reidratação é mais rápida quando a cultivar apresenta decréscimos mais lentos no metabolismo de N no período de seca, associado a menores danos na capacidade fotossintética. / Increased demand for food production and the possibility of global climate change has promoted renewed interest in photosynthesis research. It is expected that with the photosynthetic improving the crop productivity increase. For this, besides of the use of biotechnological practices, further studies are needed about intrinsic limitations of the photosynthetic process that can contribute to the identification of targets for genetic engineering. In this context, this thesis discusses specific questions about photosynthesis regulation C4 by nitrogen nutrition, water deficit and the interaction of these two factors. In the chapter I, it was developed a study of the effects of nitrogen nutrition in the internal diffusion of CO2. It was observed that the leaf nitrogen (N) is essential for the internal CO2 conductance (Δ 18O-gm). A lower leaf N induces initial reductions in Δ18O-gm by lower activity of the carboxylation enzymes. With N leaf reduction in older leaves anatomy changes began to contribute to the regulation of Δ18 O-gm. In the chapter II, the genotypic variation of sugarcane to photosynthetic parameters and leaf nitrogen was explored, involving the photosynthetic nitrogen use efficiency (PNUE) and heritability analysis. The variability of the genetic material is explained mainly by gas exchange parameters that contributed to the grouping of materials into three groups. From this, it is possible examine the differences between the materials in response to nitrogen nutrition. Furthermore, gas exchange parameters such as CO2 assimilation rate and stomatal conductance along with PNUE showed high heritability in the narrow sense. Finally, the chapter III investigated the regulation of CO2 assimilation metabolism in response to water deficit sugarcane leaves and how nitrogen metabolism is involved in this process. Different factors involved in the negative regulation of photosynthesis were identified. Interestingly, changes in nitrogen components only contributed to metabolic inhibition in severe stress. Additionally it noted that overcoming metabolic inhibition during rehydration is faster when the cultivar presents slower decreases in N metabolism during water deficit, associated with less damage to the photosynthetic capacity.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21805号 / 農博第2318号 / 新制||農||1065(附属図書館) / 学位論文||H31||N5177(農学部図書室) / 京都大学大学院農学研究科農学専攻 / (主査)教授 白岩 立彦, 教授 奥本 裕, 教授 稲村 達也 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Les travaux de cette thèse se sont situés autour de la relation entre discrimination isotopique du carbone 13 et échanges gazeux foliaires. Le modèle établi par Farquhar et al. (1982) permet de prédire la discrimination contre le 13C pendant la photosynthèse (delta13C) en tenant compte des processus de diffusion, de carboxylation et décarboxylation engagés pendant la photosynthèse. Cette relation permet d'utiliser delta13C comme indicateur de l'efficience d'utilisation de l'eau (WUE, quantité de carbone fixé en fonction de l'eau consommée), un paramètre particulièrement important dans un contexte de changement climatique, d'agriculture et de sylviculture. Le modèle de delta13C a également été utilisé pour estimer la conductance mésophyllienne au CO2 (gm), un paramètre qui limite fortement la photosynthèse via la disponibilité en carbone dans le chloroplaste. Au cours de nos travaux, nous avons analysé le modèle delta13C pour identifier les paramètres les plus influents dans le modèle, et mis en évidence que l'utilisation du "modèle simple" de delta13C (ignorant gm et les processus de décarboxylation) peut induire un biais important dans l'estimation de WUE. Dans un second temps nous nous sommes concentrés sur les possibles variations à court-terme de gm, un domaine encore sujet a débat. Nous avons confirmé que gm était sensible aux variations de CO2 et d'irradiance sur toutes les espèces d'arbres mesurées dans cette étude. Nous avons aussi montré que ces variations rapides ne peuvent pas être dues a des variations des autres paramètres du modèle, à l'exception possible du paramètre b (discrimination pendant la carboxylation). Nous suggérons que les prochaines études dans ce domaine portent sur (i) la possible variabilité environnementale et génétique du paramètre b et (ii) les mécanismes à l'origine des variations rapides de gm (aquaporines et anhydrases carboniques) / This work was focused on the relationship between isotopic discrimination of 13C during photosynthesis (delta13C) and leaf gas exchange. The model of Farquhar and colleagues (Farquhar et al. 1982) predicts delta13C by accounting for diffusion, carboxylation and decarboxylation processes during the photosynthesis. This relationship is widely used and delta13C is frequently considered as a proxy water use efficiency (WUE, the amount of water required to fix a amount of carbon), an interesting parameter in the context of climate change, crop production and sylviculture. The delta13C model is also used to assess mesophyll conductance to CO2 (gm), that strongly limits photosynthesis via the availability of carbon in the chloroplast. Along this work we analyzed the delta13C model and identified the most important parameters, and highlighted that using the "simple form" of the model (which ignores gm and the decarboxylations) could lead to misestimating WUE. We also focused on the possible rapid variations of gm, a subject still under debate. We confirmed that gm was sensitive to rapid variations of CO2 and irradiance in all species tested in this study. We also showed that apparent rapid variations of gm could not be induced by variations of other parameters in the model, with the exception of parameter b (discrimination during carboxylation). We propose that future studies should focus on (i) the possible environmental and genetic variability of parameter b, and (ii) the physiological processes able to change gm at short time scales (aquaporins and carbonic anhydrase).

Die vorliegende Arbeit liefert neue Kenntnisse über das Konkurrenzverhalten der Sprossscheitelschichten bei der Blattmesophyllbildung und trägt dadurch zum Verständnis der Entwicklungsgeschichte höherer Pflanzen bei. Weißbunte Pflanzen von Peperomia serpens SW. LOUD, Sedum rubrotinctum R. T. CLAUSEN, Pedilanthus tithymaloides (L.) POIT. und Plectranthus coleoides BENTH wurden verwendet, um den Bau des Sprossscheitels und die chimärische Natur des Laubblattes zu analysieren. Durch die Untersuchungen zum Bau des Sprossscheitels und zur Blattanatomie wurden die Anzahl initialer Sprossscheitelschichten und die periklinalchimärische Natur der untersuchten Pflanzen bestätigt. Mit Hilfe von Mittelwertvergleichen der Mächtigkeit L2- und L3-bürtiger Mesophyllgewebe wurde die Beteiligung genetisch verschiedener internaler Sprossscheitelschichten an der Bildung des Blattmesophylls bei Sedum rubrotinctum, Pedilanthus tithymaloides und Peperomia serpens erfasst. Die Existenz histogenetisch grüner L2- oder L3-bürtiger Gewebe verursacht eine Zunahme der Blattquerschnittfläche (Sedum rubrotinctum) und eine Vergrößerung der Blattmesophyllhöhe (Peperomia serpens und Pedilanthus tithymaloides). Es wurden Regenerationsversuche an Blattstecklingen der Periklinalchimäre von Peperomia serpens und Sedum rubrotinctum durchgeführt. Durch In-vivo-Provozierung von Adventivsprossen an Blattstücken und achselknospenfreien Sprossen gelang es, die zwei untersuchten heterohistischen Musterpflanzen von Peperomia serpens ('GGW' und 'GWG') in grüne und weiße Nachkommen zu zerlegen. An Blattstecklingen bildeten sich in der Mehrzahl L3-bürtige Regenerate (ca. 75 %). Eine Beteiligung der L2-bürtigen Gewebe bei der Regeneration war an den Blattrandexplantaten zu beobachten. Das L1-bürtige Hypoderm konnte nur in der In-vitro-Blattregeneration deutlich seine Fähigkeit zur Adventivsprossbildung zeigen. Die Blattregenerationsergebnisse bei Peperomia serpens demonstrieren deutlich, dass sich alle drei Sprossscheitelschichten (L1, L2, L3) an der Blattmesophyllbildung beteiligen können. An Blattstecklingen von Periklinalchimären bei Sedum rubrotinctum bildeten sich grüne, weiße und neue chimärische Adventivsprosse. Aus den Regenerationsergebnissen lässt sich die entscheidende Rolle der L2-bürtigen Gewebe bei der Adventivsprossbildung ablesen. Die Regenerationsergebnisse sprechen dafür, dass die Bildung der Adventivsprosse durch die Beteiligung der L2- und L3-bürtigen Gewebe hervorgerufen wurde und die L1-bürtigen Gewebe an der Adventivsprossbildung nicht beteiligt sein konnten. Demzufolge sind tiefer liegende Gewebe (L2- und L3-bürtige) des Laubblattes beider Arten bei der Bildung der Adventivsprosse entscheidender als die L1-bürtige Epidermis. Das Ausmaß der Beteiligung an der Adventivsprossbildung bei Peperomia serpens und Sedum rubrotinctum wird nicht von der genetischen Herkunft (weiß oder grün) des L2- bzw. L3-bürtigen Gewebes gesteuert, sondern durch die Lage und damit durch die Abstammung der Gewebe aus der entsprechenden Sprossscheitelschicht bestimmt. Die abschließenden Untersuchungen an Plectranthus coleoides, dessen Chlorophyll- und Ploidiechimären quantitativ analysiert wurden, verdeutlichen die Erkenntnisse über die Beteiligung der Sprossscheitelschichten an der Bildung des Blattmesophylls. Es wurde deutlich, dass die Gewebekonkurrenz im Beisein einer doppelten Markierung nicht lagebedingt sein kann, sondern aufgrund verschiedener Ploidiestufen stattfindet. / The studies presented in this thesis provide new insights into the competitive reaction of the shoot apical layers during the foliar mesophyll formation and thus contribute to understanding of plant development. The variegated plants of Peperomia serpens SW. LOUD, Sedum rubrotinctum R. T. CLAUSEN, Pedilanthus tithymaloides (L.) POIT. and Plectranhus coleoides BENTH were used to analyse the cellular organisation of shoot apex and the histogenetic constitution of the leaf. Shoot apex and leaves structural analyses confirm the number of initial shoot apical layers and the periclinal chimeric nature of investigated plants. Quantitative analysis of foliar mesophyll of Sedum rubrotinctum, Peperomia serpens and Pedilanthus tithymaloides have been used to deduce patterns of meristem layers intercellular interaction during mesophyll formation. The expression of the histogenetic green meristem layer (L2 or L3) causes a increase of "mesophyll area" (Sedum rubrotinctum) and a enlargement of "mesophyll height" (Peperomia serpens and Pedilanthus tithymaloides) in leaves. Four periclinal chimeric forms of Peperomia serpens ('GGW' and 'GWG') and of Sedum rubrotinctum ('GGW' and 'GWG'), each of which possesses normal green cell layers but a genetically different chlorophyll-deficient cell layer, were utilized to study the effect of genotype on the ability of the cell layers of in vivo and in vitro leaf cutting to regenerate adventitious shoots and to analyse the competition between apical layers and their derivatives in the plant ontogeny. Among the in vivo adventitious shoots of the leaf cuttings and leaf of Peperomia serpens, shoots were green, white and variegated. The L3-derived cell layer is alone responsible for the formation of ca. 75 % of adventitious shoots. The relative significant contribution of L2-derived cell layers to mesophyll formation increases in margin of leaf. The L1-derived hypoderm in foliar mesophyll of Peperomia serpens were apparently incapable of shoot regeneration of in vivo leaf cutting, yet in both periclinal forms clearly produced green shoots in vitro. Results demonstrate that all initial apical meristem layers in Peperomia serpens can contribute with different ability to foliar mesophyll formation. Adventitious shoots were in vivo induced on leaf of periclinal chimeric plants of Sedum rubrotinctum. Plants derived from leaf culture were three types: green, white and variegated. Among the adventitious shoots of green- and white-margined leaf of Sedum rubrotinctum, most adventitious shoots (ca. 90 %) were L2-derived, a few were L3-derived. Results demonstrate that the L1 derivatives can not contribute to foliar mesophyll formation. According to these results the internal tissues (L2- and L3-derived cell layers) of leaf are more competitive than the epidermis. The lineage of adventitious shoot is not controlled by the genetic origin of L2- and L3-derived tissues, but by the position of these derived tissues according to the shoot apical meristem layer. The last experiments on Plectranthus coleoides which have combined quantitative analysis of variegated- leaf chimeras with quantitative analysis of cytochimeras have begun to shed more light on the contribution of apical meristem layers to foliar mesophyll formation. It has revealed how the ploidy degree of apical layers derivatives in a cytochimera control leaf cell fate more than their position in the meristem.

Mesophyll conductance is (together with stomatal conductance) a crucial component of diffusion limitations of photosynthesis and it is important to understand the mechanisms of CO2 fluxes through the leaves. Here I tested a new technique for estimation of drawdown in CO2 concentration across hypostomatous leaves based on carbon isotope composition (13C) of leaf cuticle and cuticular waxes isolated from opposite leaf sides.

The present Master thesis focuses on evalution of CO2 concentration and irradiance on selected leaf anatomical parameters of European Beech (Common Beech) Fagus sylvatica L.. The process of photosynthesis is remarkably determined by numerous extrenal factors, among them by atmoshperic CO2 concentration and irradiance and is closely correlated with leaf anatomical parameters. One of these most important anatomical parameters affecting the net assimilation rate is an internal leaf surface, which corresponds to mesophyll area avialable for gas exhcange. Experimental material of the study was sampled from the leaves of juvenile trees of F. sylvatica planted in 2005 and growing under ambient (390 ppm, AC) and elevated (700 ppm, EC) CO2 concentrations on the experimental site of the Global Change Research Center AS CR at Bílý Kříž in the Beskydy Mountains. Sun and shade leaves were sampled from trees of both CO2 treatments in two seasons 3 years apart (2009 and 2012). To determine leaf anatomical parameters, the stereological methods were applied, which yield unbiased estimation of measured parameters, particularly the Fakir method for internal leaf surface determination. The EC effect was observed on the leaves sampled in 2009 only in the decrease of proportion of intercellular spaces in mesophyll. In...

Due to coal mining activities, heap substrates rich in clays with poor water permeability and lack of nutrients are relocated outside of mines representing hostile environment to the majority of vegetation. A material from the surface coal mines in Sokolov forming the Velká Podkrušnohorská Heap (VPS) form large locality showing characteristics of anthropogenically devasted landscape. The aim of the present study was to compare leaf structural and biochemical parameters with relation to a leaf reflectance of two pioneer tree species Salix caprea and Populus tremula with regard to leaf water regime and leaf adaptation to a water loss. From the methodological point of view, the study aimed on contribution to determine relation of selected leaf structural parameters to leaf reflectance what has not been intensively studied yet. The foliage of trees P. tremula and S. caprea grown on succession localities S2 a S3 for 30 years was used as a material for my study. The material was studied for its structure using the leaf cross sections nd abaxial epidermal strips (thickness of the leaf tissue layers and of a leaf, stomatal size density and area). Other studied parameters were contents of photosynthetic pigments, specific leaf area (SLA), water potential and leaf reflectance in regions of photosyntetically...

No description available.

La sequera és una de les majors limitacions per a l’agricultura en general, factor que pot incrementar d’acord amb les prediccions del canvi climàtic. Per això, reduir l’ús de l’aigua en el reg i augmentar l’eficiència en l’ús de l’aigua (EUA) constitueix una de les majors prioritats per aconseguir una agricultura sostenible. L’EUA és un balanç entre guanys de biomassa i les despeses d’aigua. Aquesta Tesi s’ha centrat en l’estudi de 3 dels processos fisiològics que afecten a l’ús de l’aigua i a la producció de la planta en el cas de la vinya, i que per tant poden ser considerats factors potencials per millorar l’EUA: (1) conductància del mesòfil, (2) transpiració nocturna (3) respiració. Els resultats d’aquesta Tesi revelen que la conductància del mesòfil i la respiració són els principals components per millorar l’EUA permetent millorar l’assimilació de carboni o minimitzant les pèrdues del carboni fixat per la fotosíntesis