A review of the correlation of flooding adaptability and carbohydrates in plants

Enhancing atmospheric CO2 levels in commercial glasshouses is a widely used technique to increase productivity, but has high-energy costs and detrimental environmental impacts due to frequent ventilation of the glasshouse (to prevent plant diseases) releasing CO2 into the atmosphere. Previous studies suggest that enrichment of the root zone (RZ) with CO2 (RZ CO2) may be a more economic and sustainable alternative to aerial CO2 enrichment. This thesis aimed to compare the effects of RZ dissolved inorganic carbon (DIC) enrichment by adding either bicarbonate (HCO3-) or gaseous CO2 to hydroponic and aeroponic systems, and to determine the physiological and molecular mechanisms by which plants respond to RZ DIC. Supplying hydroponically grown plants with high bicarbonate concentrations (20 mM) inhibited growth of lettuce, pepper and tomato. However, lower concentrations increased biomass accumulation in lettuce (10% increase at both 1 mM and 5 mM HCO3-) and pepper (10% increase at 1 mM HCO3-), but had no effect in tomato. Exposing plants to 1 mM NaH13CO3- significantly increased shoot δ13C values over time, therefore confirming the uptake of DIC by the roots. Root δ13C values also significantly increased over time, however higher values at the beginning of NaH13CO3- exposure suggested root-to-shoot transport of DIC. Nutrient solution pH did not affect root carbon uptake, but shoot δ13C values were lower in those plants exposed to lower pH levels (5.8) compared to those exposed to fluctuating pH (between 6.3 and 6.7), suggesting differences in root-to-shoot transport of DIC. Thus, root carbon uptake was independent of the form in which CO2 was provided (gaseous CO2 at pH 5.8; HCO3- at higher pHs). Adding 1 mM HCO3- to hydroponically grown plants did not change foliar nutrient content, but K, P, N, Zn, Cu and Mn concentrations decreased at 20 mM HCO3-, suggesting nutrient deficiencies could limit growth. Applying 2000 ppm RZ CO2 to hydroponically grown lettuce, tomato and pepper did not affect biomass accumulation. Applying 1500 ppm CO2 to the RZ of aeroponically grown lettuce increased shoot biomass between 19-25% (in 4 independent experiments) compared to those grown with 400 ppm RZ CO2. However, leaf gas exchange measurements were inconsistent and therefore increased biomass could not be attributed to higher photosynthetic rates. In another 3 independent experiments, applying 1500 ppm CO2 to the RZ of aeroponically grown lettuce did not stimulate biomass accumulation, probably because the plants were exposed to higher night temperatures. Similarly, pepper and tomato did not show any biomass response to elevated RZ CO2, suggesting that the responses to RZ CO2 concentration are environment- and species-dependent. Nutrient analysis indicated that aeration with high RZ CO2 decreased lettuce foliar Mg and S concentrations, whereas root N concentrations were higher than control plants. Multi-hormone analysis of foliar and root tissues revealed that lettuce plants showed few differences in hormone status following RZ CO2 enrichment. High RZ CO2 increased foliar jasmonic acid concentration of lettuce, but the physiological significance of this change is not clear. Pepper plants showed significantly higher foliar 1-aminocyclopropane-1-carboxylic acid and lower trans-zeatin and salicylic acid concentrations, as well as lower root N6-(Δ2-isopentenyl) adenine and higher salicylic acid and gibberellic acid concentrations. These hormonal responses were associated with lower leaf area expansion of pepper plants exposed to elevated RZ CO2. Finally, transcriptome analysis of lettuce plants indicated that fatty acid biosynthesis, amino acid biosynthesis and carbon metabolism appeared to be the major pathways enriched in roots exposed to elevated RZ CO2. In addition, proteins related to the cell walls and membranes seemed enhanced under elevated RZ CO2. Although increased CO2 concentration around the roots caused major transcriptomic restructuring, the aerial parts of the plants showed limited transcriptomic changes. Taken together, this thesis is the first study of the responses of several horticultural species to elevated RZ CO2 within different growing systems in order to decipher the impact that elevated RZ CO2 has on crop productivity. Although bicarbonate enrichment of hydroponics and RZ CO2 enrichment of aeroponics stimulated biomass accumulation of lettuce in many experiments, further work is required to fully understand the physiological response mechanisms to RZ CO2. Whether the root transcriptomic changes in response to elevated RZ CO2 represent an adaptive response to their environment requires a better temporal understanding of changes in specific genes. Ultimately, whether these changes are functionally significant to shoot growth seems to be strongly environmentally regulated.

Effect of 6-Benzylaminopurine on Morphogenesis and Production Process of Sweet Pepper (Capsicum annuum L.)

Arbuscular mycorrhizal (AM) fungi are soil borne fungi forming symbiotic relationship with majority of higher plants providing a direct link between soil and plant roots. AM fungi undergo a multi-step colonization process before benefiting the host plant. The strong glue glomalin is a glyco protein produced by an AM fungi. The deposition of glomalin on soil particles leads to buildup and stabilization of aggregates, which leads to better soil structure which in turn leads to increased soil water availability under water stress condition. The mycorrhizal colonization is effective aggregators and therefore management of mycorrhizal fungi can be considered as a biological amendment for soil structure and other soil physical properties. Mycorrhizal plants could take up more metal nutrients via extraradical hyphae, which provide larger surface areas than the roots alone and reduce the distance for diffusion, thereby enhancing the absorption of immobile metal nutrients (especially Phosphorus and Zinc). Mycorrhizal inoculated plants produce larger biomass as a direct consequence of improved photosynthetic activities and translocate 20 to 30% of the assimilated C to the underground where mycorrhizal structures conserve soil carbon. AM symbiosis enhanced the plant growth by increasing plant access to immobile mineral ions mainly Phosphorus and Zinc, improving physical conditions and by binding heavy metals into roots that restricts their translocation into shoot tissues. The mycorrhizal symbiosis assists in biofortification of micronutrients such as Fe and Zn in maize grain irrespective of calcareous and non-calcareous soils. The mechanism involved in improved micro nutrition of maize includes acidification of rhizosphere; siderophore production enhanced physiologically active Fe and production of anti-oxidants besides synergistic interaction between P and micronutrients. Key words: Mycorrhiza, soil aggregation, micronutrients, carbon sequestration, heavy metals, enzymatic activity, glomalin, biofortification.

کودهای زیستی، متشکل از ریزموجودات مفید، به عنوان جایگزین مناسبی برای کودهای شیمیایی در تولید محصولات گلخانه‌ای در سامانه‌های کشاورزی پایدار محسوب می‌گردند. در تحقیق حاضر تاثیر غلظت‌های 0(شاهد)، 80، 160، 250 و 330 اسپور در میلی‌لیتر قارچ اندوفیت P. indica بر میزان گلدهی و پارامترهای رشدی ریشه گیاه توت‌فرنگی (رقم گاویتا) تحت شرایط کشت هیدروپونیک در قالب طرح کاملا تصادف در 28 تکرار مورد بررسی قرار گرفت. قارچ P. indica در غلظت‌های مختلف بصورت روش تزریق پای بوته به گیاهان توت فرنگی تلقیح شد. میزان گلدهی‌ 8 ماه بعد از تلقیح برای تمام گلدان‌ها اندازه‌گیری شد. یک هفته پس از آخرین برداشت طول و وزن تر و خشک ریشه اندازه‌گیری گردید. نتایج نشان داد که بیشترین و کمترین میزان گلدهی، طول و وزن تر وخشک ریشه مربوط به تیمار 330 اسپور در میلی‌لیتر و شاهد به ترتیب با 37، 72 ، 71/76 و 52/75 درصد افزایش نسبت به شاهد می‌باشد و همچنین بین تیمارهای شاهد، 80 و 160 اسپور در میلی لیتر در مورد صفات مذکور اختلاف معنی‌داری مشاهده نشد در حالی که تیمارهای 330 و 250 اسپور در میلی‌لیتر با بقیه تیمارها در (01/0P≤) اختلاف معنی‌داری داشتند. بنابراین می‌توان نتیجه گرفت که غلظت‌های بالای قارچ P. indica می‌تواند باعث افزایش صفات مذکور و در نتیجه بر رشد و عملکرد گیاه تاثیر مثبت داشته باشد.

Fructans, the polymers of fructose (Fru), are major non-structural storage carbohydrates in the vegetative tissues of many higher plants including temperate forage grasses and cereals, as well as major crop plants such as wheat and barley. Fructans play an important role in assimilate partitioning, plant development, environmental stress tolerance etc. Fructans also have a vast application potential in nutrition and medicine. The main focus of this dissertation is the fructan biosynthetic pathway in barley leaves. Its major aspects are the identification of sucrose:sucrose 1-fructosyltransferase (1-SST) as a pacemaker enzyme, regulation of the promoter of sucrose:fructan 6-fructosyltransferase (6-SFT) - one of the main fructosyltransferases (FTs) and the role of vacuolar invertases during fructan metabolism. Excised barley leaves exposed to continuous light accumulate large amounts of fructans containing β(2-6) linkages with β(2-1) branches, the so-called graminans. The pathway for graminan biosynthesis has not been well characterised, but it has been proposed that the successive action of two main enzymes, 1-SST and 6-SFT is involved (1-SST/6-SFT model). To demonstrate the validity of this model, excised leaves were subjected to a light-dark regime known to sequentially induce fructan accumulation and mobilization. The pattern of accumulation of soluble carbohydrates, the level of 1-SST and 6-SFT activities, and the expression of the corresponding genes, all indicate that the diversion of sucrose (Suc) into the pathway fructan synthesis is initiated by 1-SST induction. The stability of transcripts and enzyme activities of 1-SST and 6-SFT were compared, using appropriate inhibitors. The transcripts of 1-SST and enzymatic activity are subject to a rapid turnover and respond more quickly than 6-SFT. The much higher responsiveness of 1-SST to regulatory processes clearly indicates that it plays the role of the pacemaker enzyme of fructan synthesis in barley leaves. Plants regulate fructan synthesis in response to several internal and external stimuli primarily through the modulation of gene expression of FTs. Little is known about signal perception and transduction events that control the expression of FT genes. The regulatory sequences of FT genes are valuable tools to decipher the underlying signaling events. Using PCR-based genome walking procedures, the promoter of 6-SFT gene corresponding to 1.6 kb of the upstream region of the coding sequence, was cloned. The promoter activity of the cloned sequence was investigated in transient assays by fusing it to a reporter gene [uidA encoding β-glucuronidase, (GUS)] and by microprojectile bombardment of excised barley leaves. Strong expression of the GUS gene was observed in leaves induced for fructan biosynthesis by Suc and light, indicating that the cloned sequence contains the necessary cis acting elements conferring Suc and light induction of 6-SFT transcription. Arabidopsis thaliana has been extensively used to study the sugar induced signal transduction pathways in plants. In order to investigate the signaling events involved in the activation of the 6-SFT promoter, stably transformed Arabidopsis plants harboring the 6-SFT promoter driving the expression of the GUS reporter gene, were obtained. Though Arabidopsis is a non-fructan producing plant, the sugar-regulated activation of the barley 6-SFT promoter is maintained in Arabidopsis. The inhibitors of protein phosphatases and protein kinases, and a chelator of calcium, known to block Suc induction of 6-SFT gene expression in wheat, were effective in Arabidopsis too, suggesting that this signal transmission process seems to be conserved between cereals and Arabidopsis. These transgenic plants are valuable to study the activity of the barley 6-SFT promoter further and identify the transcription factors that interact with the key promoter elements. Invertases play a central role in the metabolism of Suc, the main product of photosynthesis and substrate for the synthesis of the fructans. Soluble acid invertase (SAI) isoforms are present in the vacuoles and are believed to be the ancestors of fructosyltransferases FTs. No SAI sequences are available from barley yet. In the present work, a soluble acid invertase cDNA was cloned from barley (HvSAI) and functionally characterized by heterologous expression in Pichia pastoris. Furthermore, the expression of HvSAI gene was studied in excised leaves and roots. The recombinant HvSAI cleaves Suc efficiently, but despite very high amino acid sequence similarity to FTs, is devoid of FT or fructan hydrolase like side activities. Compared to the FTs, the activity of the recombinant HvSAI is relatively easily saturable (Km of 13.5 mM for Suc) and possesses a higher temperature optimum (10°C more that 1-SST). The mRNA levels of HvSAI are constitutive and not affected much by enhanced sugar levels in excised leaves and roots, by Suc supply or continuous illumination of cut leaves. The cloning of SAIs will help to investigate their role in the regulation of fructan metabolism and decipher the structure-function relationship between SAI and FTs.

طبق تحقیقات انجام شده تولید و فعالیت هورمون‌های گیاهی تحت تأثیر عوامل طبیعی و عناصر غذایی مورد نیاز گیاه قرار گرفته و نیتروژن مهم‌ترین تأثیر را بر تولید و انتقال جیبرلیک اسید به اندام‌های هوایی گیاه دارد. به‌منظور بررسی اثر جیبرلیک اسید و نیتروژن بر برخی پارامترهای فیزیولوژی و عناصر غذایی کم‌مصرف پسته (رقم قزوینی) تحت تنش شوری، آزمایشی به‌صورت فاکتوریل در قالب طرح کاملا تصادفی با سه تکرار انجام شد. تیمارها شامل سه سطح شوری (صفر، 1000 و 2000 میلی‌گرم کلرید سدیم در کیلوگرم خاک)، سه سطح نیتروژن (صفر، 75 و 150 میلی‌گرم در کیلوگرم خاک از منبع نیترات آمونیوم) و سه سطح جیبرلیک اسید (صفر، 250 و 500 میلی‌گرم در لیتر) بودند. نتایج این آزمایش نشان داد که شوری کلرید سدیم محتوای کاروتنوئید و شاخص کلروفیل فلورسانس را نسبت به شاهد کاهش داد، ولی با اعمال تیمارهای جیبرلیک اسید و نیتروژن پارامترهای ذکر شده با افزایش چشمگیری نسبت به شاهد روبرو شد. با توجه به این‌که شوری کلرید سدیم سبب افزایش میزان پرولین برگ گردید، کاربرد 150 میلی‌گرم نیتروژن و محلول‌پاشی 500 میلی‌گرم در لیتر جیبرلیک اسید این پارامتر را به ترتیب 55 و 26 درصد افزایش داد، اما کاربرد توأمان این دو تیمار در بالاترین سطوح خود باعث افزایش 79 درصدی پرولین نسبت به شاهد شد. نتایج این آزمایش هم‌چنین نشان داد، با افزایش شوری کلرید سدیم غلظت عناصر آهن، منگنز و روی افزایش ولی غلظت مس اندام هوایی و ریشه کاهش یافت، لیکن با کاربرد 150 میلی‌گرم نیتروژن و با مصرف 500 میلی‌گرم در لیتر جیبرلیک اسید غلظت مس نیز افزایش یافت. به‌طور کلی نتایج این آزمایش نشان داد در شرایط شوری کلرید سدیم، کاربرد جیبرلیک اسید و نیتروژن به تنهایی و یا توأمان از طریق بهبود پارامترهای فیزیولوژی و هم‌چنین افزایش غلظت عناصر غذایی کم مصرف عملکرد گیاه پسته در شرایط تنش شوری کلرید سدیم را بهبود بخشید.

Gene induction during plant-microbe interactions : the role of chitinases during fungal infection and the investigation of mycorrhiza-induced genes in the model plant "M. truncatula"

Increasing global population is magnifying demand for raw resources from mining, with the resulting mine soil overburden low in the carbon (C) and nitrogen (N) necessary for plant rehabilitation. Unabated growth in anthropogenic carbon dioxide (CO2) emissions is changing plant and spoil C and N cycles. The full extent of these changes is unknown, adding further complexity to mine spoil rehabilitation. Biochar is a promising soil rehabilitation product, with a stable aromatic structure derived from the anoxic pyrolysis of organic matter. This study aimed to investigate the C and N pools in mine soil, and plant physiological response to the use of biochar produced at different temperatures under elevated and ambient atmospheric CO2. An experiment was established in four biochambers, with controlled temperature, CO2 and UV, in the University of Western Sydney. Five species of plants were grown in mine spoil pots treated with three types of pinewood biochar, slow pyrolised at 650 oC, 750 oC, and 850 oC respectively, with CO2 concentrations at 400 ppm and 700 ppm. Plant foliar, stem, and root samples and soil samples were collected and analysed for total C (TC), total N (TN), C isotope composition (δ13C) and N isotope composition (δ15N) plant biomass and soil moisture. The results showed that elevated CO2 resulted in the further depletion of δ13C, with the 700 ppm CO2 reducing foliar δ13C compared to the 400 ppm CO2 treatments, at -36.8‰ and -30.9‰ respectively. Elevated CO2 also created a CO2 fertilisation effect, with the 700 ppm CO2 increasing plant foliar TC compared to the 400 ppm CO2 treatment, at 1.35 g and 1.05 g respectively. Evidently, elevated CO2 increased plant water use efficiency (WUE) and plant photosynthesis. Biochar amendment to the mine soil significantly increased soil moisture, plant biomass, and further depleted plant δ13C and δ15N. The biochar treatment significantly increased soil moisture and reduced plant δ13C which, in combination, provides strong evidence for the ability of biochar to increase the water holding capacity of soil, and water bioavailability to plants. Reduced δ15N provides evidence that biochar amendment increased the availability of N sources with a depleted 15N value in the soil with significant N limitation. Complementing the growing literature on the benefits of biochar, these results showed that the amendment of soil with biochar was able to increase plant growth success in a poor C and N environment, reducing the leaching of soil N and increasing the bioaccumulation of soil C and N compared to the soil without the biochar treatment.

In natural and agricultural ecosystems, arbuscular mycorrhizal (AM) fungi play a major role in plant nutrition. In AM symbiosis, the AM fungi extract mineral nutrients from the substrate and transfer them to the host plant. Inside the roots of the host plant, the intraradical hyphae form tree like structures (arbuscules) where the nutrients are released to the plant fungal interface. In return, the AM fungi receive carbohydrates from the plants. Specialized transport systems enable nutrient uptake from the substrate and translocation across membranes. As main components of organic molecules, phosphorus (P), nitrogen (N) and carbon (C) are of particular importance for symbiotic nutrient exchanges. This work is focused on a range of genes that encode proteins contributing to transport molecules (P, N and C nutrients) across cellular membranes in the plants Populus trichocarpa (poplar) and Sorghum bicolor (sorghum), and in the AM fungus Rhizophagus irregularis. In the AM fungus R. irregularis (formerly Glomus intraradices), we identified and characterized a novel functional ammonium transporter (AMT), GintAMT3. Quantification of transcript abundances in the extraradical mycelium (ERM) and the intraradical mycelium (IRM) during symbiosis with poplar and sorghum revealed that GintAMT3 was highly expressed in the IRM of AM roots. Phylogenetic analysis showed further, that the six glomeromycotan AMTs share high sequence similarity, but are distinct to AMTs of other fungal phyla. To functionaly analyze GintAMT3, we expressed GintAMT3 in a yeast deletion mutant devoid of all AMTs. The heterologous expression revealed that GintAMT3 is a low affinity transporter. Heterologous expression of GFP tagged GintAMT3 in yeast showed that GintAMT3 is localized in the plasma membrane and the vacuolar membrane. Further, we could show that expression of GinAMT3 is dependent on the N nutrition status and the fungal C status. Taken together, our data suggested that GintAMT3 is the main export carrier for ammonium at the arbuscular site. Using mRNA sequencing, we could show that low N availability significantly increased gene expression of the AM fungus, including genes involved in cell growth and membrane biogenesis as well as genes involved in signaling and metabolic processes. High abundances of genes related to N metabolism, including glutamine synthase, aminotransferase, AMTs as well as arginases, indicated a high turnover rate of N in the symbiotic root tissue. Depending on P availability, gene expression of AM phosphate transporters (PT) and AMT changed. Induction of PT and AMT under low-P availability indicated that the AM fungus transfers more nutrients to the host plant. Further, we identified amino acids transporters and H+/oligopeptide transporters specifically induced in mycorrhizal poplar roots, indicating that amino acids are transferred between the AM fungus and the plant. In poplar, we found that root colonization and low-N conditions resulted in the down-regulation of defense gene expression, suggesting that the plant stimulated symbiotic interactions with the AM fungus. We showed that root colonization specifically induced expression of known and newly identified PT and AMT in poplar and sorghum. Specific induction of nutrient transporters upon starvation strongly indicated that they are essential components of a functional symbiosis and suggested they are located in AM roots. Furthermore, root colonization suppressed the expression of genes involved in P starvation response, indicating that root colonization efficiently alleviated P stress of the plant. Moreover, we could show that the annual sorghum is more dependent on the AM fungus than the perennial poplar, but also that more P and possibly also more N is transferred from the AM fungus to the host plant. Non-mycorrhized sorghum accumulated similar quantities of P as AM sorghum under conditions, in which only the AM fungus had access to the P source. Poplar on the other hand accumulated less P in AM plants. In addition, we observed that a subset of poplar Pht1 transporters was regulated independently on the AM fungus, but depending on the P availability of the substrate. To deepen our understanding about symbiotic C exchange, we made transcriptome analysis and qRT-PCR to investigate the role of carbohydrate transporters in AM symbiosis between R. irregularis and, poplar and sorghum, respectively. In R. irregularis, the monosaccharide transporter GintMST2 was specifically induced in the IRM independently on the nutrient condition. Interestingly, we observed the down-regulation of many carbohydrate transporters in AM roots of poplar and sorghum. However, in poplar, we identified one carbohydrate transporter, which might be involved in symbiotic C transfer. In conclusion, our data on C transport suggested that carbohydrates are taken from the plant by the AM fungus instead of actively transferred to the fungus by the host plant. Taken together, the data summarized in my thesis add to our understanding of nutrient transport in AM symbiosis under different environmental conditions and help elucidating the underlying mechanisms. Regarding climate changes and resources shortening, a precise understanding of the efficiency of AM symbiosis may help to increase the efficiency of sustainable agriculture.

To understand the response of selection of Vitis thunbergii, We Compared phenotypic variation and correlations among agronomic characters including root production. Two field experiments were conducted in 1999 and 2000 at the experiment field of TARI (Taichung). Ten Lines of Vitis thunbergii Sieb.et. Zucc. var. taiwaniana and two Vitis adstricta Hance were grown in two randomized complete block designs with three replication. Two experiments differed in respect to irrigation regime. The values of eleven characters and relationships of nine characters were assessed.Most of the characters including root yield and main stem diameter showed considerable genotypic and phenotypic variations. Water flooding significantly decreased root yield and its components, however, β-sitosterol content did not differ significantly. Genotypic and phenotypic correlations revealed that root yield had significant positive correlations with main root diameter, main stem diameter, plant height branch weight and main stem weight under normal irrigation. Root yield had significant correlations with β-sitosterol content and main stem diameter under normal irrigation regime, while these correlations became insignificant under water flooding conditions.

Heat and flooding are environmental stresses that inhibit tomato growth and productivity during the hot season in Taiwan. Selecting plant lines tolerant to flooding and heat would increase the productivity of tomato during the hot season. Two-month-old plants from the tomato lines Solanum pimpinellifolium L4422, S. habrochaites L3683, S. peruvianum L1947, and the tomato (S. lycopersicum L.) 'ASVEG #6' were flooded for 5 d during the hot season in Taipei. The relative water content, stomatal conductance, and chlorophyll fluorescence in the leaves, and the antioxidant contents, and activity of antioxidative and fermentative enzymes in the roots were measured. At 12 h after flooding, L1947 revealed a rapid decrease in stomatal conductance and Fm value, higher α-tocopherol content and Fv/Fm value than L4422, and higher alcohol dehydrogenase activity than that in the other three Solanum plants. The Fm values for L1947 and L3683 decreased earlier (at 12 h) than 'ASVEG #6' and L4422 (at 24 h) after flooding. The ascorbate peroxidase activity and fresh weight in L1947 root were increased at 48 h after flooding. Thus, among the four Solanum plants studied, L1947 is more tolerant to flooding during the hot season in Taipei.

During the last decades public awareness of the limitations of traditional engineering practices and the imperative to conserve nature have led to changes in river management; including river restoration measures. The enlargement of the fluvial corridor is one of the often considered management measures. However, the high-pressure on land-use, the conflict of interests, as well as the uncertainty of vegetation and landscape development scenarios after restoration, can make their implementation difficult. In actual decision-making processes of large river restoration projects, no dynamic long-term modelling approach of potential riparian woody species development exists mainly due to the complexity of interacting driving-processes creating lateral and longitudinal gradients. So far, forest succession models applied to riparian areas are not conceived for river areas found in Central Europe and do not address explicitly environmental influences like nitrogen scarcity or drought stress important for certain riparian systems, nor they cover integrally the vegetation-hydraulics interaction. To support and enhance the decision-making processes in river restoration projects and to provide a better understanding of riparian forest dynamics and its driving-processes, the present thesis develops a coupled model of ecological and hydraulic processes to simulate riparian forest dynamics for Central European conditions, particularly for the case of enlarged fluvial corridors. The developed model RIFOD ('RIparian FOrest Dynamics') – a distribution-based forest succession model (i.e. ecological model) coupled to a quasi-2D hydraulic model – simulates short or long-term riparian forest dynamics at a yearly time step. The model, applied on a 10 times 10 m mesh grid, is spatially-explicit concerning the interactions of the ecological and hydraulic processes and integrates 65 Central European tree and shrub species. The ecological model is based on developments of different upland forest succession models, which were improved, adapted and complemented in regard to the ecological processes in riparian areas, for example concerning regeneration, nitrogen dynamics, soil water availability or flooding stress. At the basis of the modelling of physiological flooding stress response of plants, we carried out an in-depth review of the actual knowledge of the flooding stress response of Central European tree and shrub species. The review could highlight the main biotic and abiotic factors that influence species response and revealed the broad but still vague knowledge about physiological mechanisms and species-specific data of plant response. Based on the above findings, the fuzzy set theory was chosen to model flooding stress response integrating the main abiotic factors (e.g. flooding duration, -depth). The Central European tree and shrub species were classified into flooding tolerance classes by use of clustering analysis based on proxy-data, which allowed us considering indirectly the anatomical, morphological or physiological adaptations to flooding. To model mechanical flooding stress, existing mechanistic models simulating failure resistance to uprooting or stem breakage conceived for wind load studies have been adapted to the case of water flow. Required geometrical characteristics of trees and shrubs, such as crown width and crown heights, were estimated based on available field data, whereas rooting depths in dependence of the growth stage of an individual plant were simulated by developing a quasi-mechanistic vertical root growth model for Central European tree and shrub species. This root growth model allowed also a more realistic simulation of drought stress by calculating root water extraction in relation to the development stage of stand and determining species-specific and development dependent accessibility to groundwater – not integrated in the soil water balance so far. Compared to the situation in uplands, a more realistic modelling of nitrogen availability in riparian areas could be achieved by considering the loss of nitrogen via denitrifcation, as well as the loss of litter due to flooding. In opposition to existing riparian forest succession models, RIFOD considers riparian vegetation not as a purely dependent variable of flooding. Floods may affect vegetation but they are also affected by it, owing to the contribution of vegetation to hydraulic roughness. The coupling of the forest succession model to a quasi 2-D hydraulic model allowed considering this. Moreover, the quasi steady-state model approach allowed emphasizing on the ecological relevant lateral dimension and to make the model spatially explicit in the sense of vegetation-hydraulics interaction. The current version of RIFOD finds its application in riparian areas in which the geomorphological activity of the river is not a dominant process or in case of restoration projects, for widened fluvial corridors with morphologically stable stream channels. Model evaluation (validation and sensitivity analysis) revealed that RIFOD simulates plausibly the ecological gradients observed in the field and the resulting riparian forest dynamics. By applying the model at different lateral fluvial corridor designs at the River Rhone, the consequences of a restoration measure and the change of the hydrological regime for woody vegetation could be illustrated. From a management point of view, the model revealed for example that relative benefits become smaller as the width increases or that in absence of morphological activity (e.g. lateral bank erosion) the hydraulic processes alone are not sufficient for reinitiating riparian forest succession even for high energy streams such as the River Rhone. Moreover, the model allowed verifying and discussing current scientific concepts and hypotheses, as for example the intermediate stress hypothesis. Simulation results revealed that biological diversity is highest between the very low and very severe flooding stress levels confirming the intermediate stress hypothesis involving a trade-off between competitive dominant species which monopolise stable habitats and the few fugitive species that survive high levels of instability. The value of RIFOD relies in the capacity of displaying tendencies of riparian forest dynamics and associated characteristics in function of different fluvial corridor design variants. Moreover, it allows the understanding of processes and patterns in nature by allowing exploring the consequences of a set of explicitly stated assumptions that are too complex to explore by other methods. RIFOD is the first process-based riparian forest dynamics model for Central Europe and can be seen as a step forward into a more integral modelling of the riparian forest dynamics and its processes in view of a decision-aiding tool for large river restoration projects. A future integration of geomorphological processes will allow the application of RIFOD to quasi-natural river conditions.

The studies carried out during my Ph.D thesis focused on the identification of genetic mechanisms which regulate tomato fruit quality traits under abiotic (water deficit) and biotic (Botrytis cinerea) stress conditions. Specifically the work was developed through two lines of research with certain objectives: 1) Identification of candidate genes controlling tomato fruit quality in response to water deficit, through microarray tools and the use of an Introgression line (IL9-2-5). 2) The study of shelf life and Botrytis cinerea resistance of transgenic tomatoes enriched in flavonoid. In the first part of study the selected approach consisted to study the peculiar behavior of the genotype IL9-2-5, an introgression line of the cultivated Solanum lycopersicum with a 9 cM introgression from the wild species Solanum pennellii. This introgressed segment gives fruits with high soluble solids amount and previous experiments, performed in laboratory where I worked, highlighted its superior performances under water stress. This was confirmed in the present thesis. In particular, the Blum index (parameter that allows to evaluate yield of a cultivated plant under drought stress) evidenced a lower yield losses under 50% water treatment in IL9-2-5 compared with M82, in both two tolerance tests. In addition, phenotipic data for fruit quality highlighted very low changes in firmness, soluble solids and nutrient content underlining more stability under water deficit in IL9-2-5 compared with M82, in the first tolerance test. Among phenotypic data, a stability in AsA content in IL9-2-5 under 50% water treatment was noteworthy, while in M82 was evident its dramatic decrease. Also transcriptomic data were in line with the hypothesis of a more stability of the IL9-2-5, specifically its comparison between the two water treatments in microarray analysis highlighted the low fold changes of transcripts, indeed only 5 probes differentially expressed were retrieved. On the contrary, the elevated amount of TCs showing differential expression in M82 under 50% water treatment (204) indicated an activation/repression of a lots of genes involved in defense mechanisms towards abiotic stress. The correlation data (by CoExpression Tool) made possible to establish a relation among AsA metabolism, carbohydrate metabolism and water stress. This part of work allowed to identify IL9- 2-5 as a genotype to use in breeding programs to obtain fruit with good quality traits (in particular soluble solids and vitamin C amount, both important for tomato processing industry) reducing water consumption. In the second part of study, transgenic tomatoes, accumulating different flavonoid compounds, were tested to have extended shelf life and enhanced pathogen resistance to Botrytis cinerea. Comprehensively all the transgenic lines investigated were very interesting as healthy foods, but only purple and indigo tomatoes (both accumulating anthocyanins) showed 2-fold longer shelf life and increased resistance to the opportunistic pathogen tested, compared with red tomato. On the other hand, orange tomato (which accumulates flavonols) had longer shelf life compared with red tomato but shorter than purple and indigo tomatoes. In addition, orange tomato showed no resistance to Botrytis cinerea. Our data suggest that high antioxidant capacity of anthocyanins reduces the increase in reactive oxygen species, better than flavonols during late ripening stages, and scavenges H2O2 (and probably other ROS too), produced by Botrytis c. during infection, better than flavonols, stopped necrosis damns. This part of work allowed to identify all transgenic lines investigated, not only interesting as healthy foods, but also interesting to enhance fruit shelf life, but just purple and indigo to enhance also resistance to Botritys cinerea.

本研究之目的為利用台灣五葉松 (Pinus morrisonicola) 幼苗，種植於無鋁毒害的土壤(農業用土) 及平溪野外採集具有鋁毒害的土壤 (煤礦棄土)，並接種彩色豆馬勃 (Pisolithus tinctorius, P.t.) 及龜紋硬皮馬勃 (Scleroderma areolatum, S.a.) 2種外生菌根菌，苗木生長2個月後，進行不同鋁濃度 (0 μM、300 μM、1000 μM和1300 μM) 及時間 (30天和70天) 的處理，進行生物量、植體養分、可溶性碳水化合物及葉綠素濃度測定，以了解不同處理對台灣五葉松苗木生長的影響及生理效應。結果顯示，台灣五葉松之生物量以0 μM鋁並接種 P.t. 處理，具最大生物量。植體養分中氮、磷、鉀、鈣、鎂隨著鋁濃度增加而減少，鈉則隨著鋁濃度增加而增加；未接種菌根菌的植體，會有較高的鈉累積，但氮、磷、鉀、鈣、鎂濃度則較低。另外，植體中可溶性碳水化合物及葉綠素濃度也隨著鋁處理濃度增加而降低。比較兩種不同土壤的差異，農業用土即使經過了1300 μM濃度的鋁處理，土壤可置換鋁離子顯著低於煤礦棄土，證實台灣五葉松苗木在煤礦棄土上之生長及生理效應較農業用土壤劣勢。同時，台灣五葉松苗木生長於煤礦棄土中，其生長生理表現，接種菌根處理者較未接種處理者佳；而在大多數處理中，接種 P.t. 對於苗木的助益也優於接種 S.a. 之苗木。接種外生菌根菌能增加台灣五葉松在鋁逆境下的耐受性。在長期高濃度鋁處理下，未接種菌根處理下，苗木累積可溶性碳水化合物濃度明顯低於接種菌根處理者，而地下部乾重和氮、磷、鉀、鈣、鎂濃度也均大於未接種菌根處理者，證明外生菌根菌的苗木具有最優的耐鋁能力，而無外生菌根的植株則表現最差。

In this study, Scaevola sericea and Messerschmidia argentea were inoculated with two kinds ofendomycorrhizal fungi isolated from nursery (man-made cultural environment; M1), or from native coastal habitat (natural distribution; M2). Seedlings were grown in greenhouse, for 10 months, then treated with different salt concentrations (0%, 1%, 2% and 3%) and different time (1, 5, 10, 15, 30, 60 days). Finally, the biomass, plant nutrient, proline, total soluble carbohydrates, chlorophyll and chlorophyll fluorescence parameters were determined to evaluate the different treatments on plant growth and physiologic effects. With the increased salt concentration, the seedlings biomass, chlorophyll, Fv / Fm, ΦPS II and qP were decreased, but the proline, soluble carbohydrates and qN were increased. When the days of salt treatment were increased, the Na+, proline of leaves and qN were increased, but chlorophyll, Fv / Fm, ΦPS II and qP were decreased. Proline and soluble carbohydrates could be used as osmotic adjustment in leaves of S. sericea, but the increased K+ accumulation in root could increase osmotic potential. Increased proline concentration both in leaves and roots of M. argentea could resist osmotic stress. Mycorrhizal inoculation could increase the tolerance of S. sericea and M. argentea to salt stress, but buth with slight difference. The proline and soluble carbohydrates of S. sericea treated with M1 were significantly lower than those treated with M2. It showed that M1 could be more adapted to salt stress than M2. The root dry weight and phosphorus concentrations of M. argentea inoculated with M2 were higher than those inoculated with M1, but Na+, proline and soluble carbohydrates were significantly lower than those inoculated with M1. It showed that M2 could be more adapted to salt stress than M1. In conclusion, different time and salt concentrations were used to test the influences of salt stress on S. sericea and M. argentea. It showed that mycorrhizal inoculation played an important role in the growth and resistance to salt stress for seedlings growth.