京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19740号 / 工博第4195号 / 新制||工||1647(附属図書館) / 32776 / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 庸裕, 教授 阿部 竜, 教授 陰山 洋 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(生命科学) / 甲第20099号 / 生博第359号 / 新制||生||47(附属図書館) / 33215 / 京都大学大学院生命科学研究科統合生命科学専攻 / (主査)教授 福澤 秀哉, 教授 佐藤 文彦, 教授 河内 孝之 / 学位規則第4条第1項該当 / Doctor of Philosophy in Life Sciences / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21789号 / 工博第4606号 / 新制||工||1717(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 庸裕, 教授 佐藤 啓文, 教授 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The research in this thesis concentrates on investigation of the ecology of Arundinaria species for restoration purposes. Arundinaria species are key components in the canebrake ecosystem that was once prominent in the southeastern United States. Arundinaria still occurs as an understory component of bottomland hardwood forests, but with intense agricultural development and urbanization over the past 200 years, canebrakes are now a critically endangered ecosystem with greater than 98% loss. Specifically the thesis addresses the establishment of Arundinaria with other plant species and site preparation techniques. This study indicated that A. gigantea planted into plots dominated by non-native plants benefited significantly more from site preparation (soil tillage, herbicide application) than cane planted into native-species-dominated assemblages. The last portion of the research examined effects of inundation on A. gigantea and A. tecta. Arundinaria tecta appeared to be more flood tolerant than A. gigantea, reflecting habitats in which these species are known to occur.

No description available.

The progressive increase in the global population and the rapidly changing climate have put unprecedented pressure on crop production. Cowpea is one of the world’s most important leguminous crops, contributing to food security and environmental sustainability. However, cowpea productivity is limited due to waterlogging stress. The main objective of this study was to explore physiological and biochemical mechanisms to understand how cowpea genotypes respond to waterlogging stress. Four studies were conducted in controlled and field conditions to achieve these objectives. Study 1 characterized the waterlogging tolerance of 30 cowpea genotypes in a controlled environment using 24 morphophysiological parameters with waterlogging tolerance coefficients and multivariate analysis methods. 10% of the genotypes exhibited high tolerance to waterlogging stress, and the genotypes UCR 369 and EpicSelect.4 were identified as the most and least waterlogging tolerant, respectively. Study 2 evaluated the key parameters influencing carbon fixation of UCR 369 and EpicSelect.4 at the reproductive stage. The less tolerant EpicSelect.4 experienced high downregulation of stomatal and non-stomatal limiting factors during waterlogging and recovery, resulting in decreased carbon assimilation rates. UCR 369 rapidly developed adventitious roots, maintained biomass, and restored pigments and metabolites to sustain photosynthesis. A two-year field experiment was conducted in study 3 to quantify the effects of waterlogging on the yields, physiology, and biochemistry of cowpeas at different growth stages. The most apparent impact of waterlogging stress occurred at the reproductive stage, followed by the vegetative and maturity growth stages. Studies suggest that diverse cowpea genotypes have distinct physiological and biochemical mechanisms in response to waterlogging stress. In addition, the tolerant genotypes and traits identified herein can be used in genetic engineering and cowpea breeding programs that integrate increased yield with waterlogging stress tolerance.

No description available.

The photosynthesis of the aerial roots of epiphytic orchids has been the subject of numerous studies. However, the roots are always evaluated as a homogeneous structure, even though they actually consist of significantly different areas. This work deals for the first time with the possibility of the spatial distribution of photosynthesis between the root layers, specifically the cortex and the stele. A combination of various microscopic techniques, the histochemical characterization of the apoplastic barriers and the immunohistochemical localization of the photosynthetic enzyme phosphoenolpyruvate carboxylase has been used. The results show that well-developed chloroplasts in the stele probably occur in the subfamily Epidendroideae in all epiphytic representatives, while in the subfamily Vanilloideae they occur occasionally. The ultrastructure of chloroplasts from both areas is systematically different, so it is likely that their functions also differ. Apoplastic barriers are prominent in the roots and differentiate early during root development, which can effectively isolate chloroplasts in the stele from the cortex. Chloroplasts also occur in the sclerenchyma cells of the stele, where were identified hitherto unknown pits in cell walls that could provide gas exchange within the stele....

Seagrasses are well known for the important ecological roles they play in coastal marine waters worldwide. However, the severe rate of decline observed in seagrasses this century is expected to accelerate with climate change. Conservation efforts can be improved by quantifying physiological thresholds of seagrasses and using these estimates in modeling to forecast changes in distribution. This study examines the response of eelgrass (Zostera marina L.) across current temperatures to look for early warning signs of vulnerability and to evaluate the ways we determine critical thresholds for survival. Whole eelgrass ramets, collected from three beds in Morro Bay, California, were used to develop photosynthesis-irradiance (P-I) curves from 10-20°C. Productivity was not affected by changes in temperature when traditionally measured as the light-saturated photosynthetic rate to dark respiration rate (P:R) ratio. However, photosynthesis in light-limited conditions declined at higher temperatures, suggesting a decrease in productivity when coupled with the increased respiration rates observed at higher temperatures. Irradiance thresholds increased with temperature; critical irradiance was the most sensitive to increases in temperature due to the inclusion of overnight energy use, which also increases with temperature. Measurements of root and rhizome respiration, overnight respiration, and variation across eelgrass beds reveal that these are important components to consider when calculating survival thresholds to use in modeling. Differences in physiological responses across beds suggest that some eelgrass beds operate more efficiently than others in current conditions and are likely to be more resilient to the progressing stressors of climate change. Management of eelgrass in the face of climate change will require reliable distribution forecasts, and therefore accurate estimates of physiological thresholds, to guide mitigation and restoration efforts.

For optimal growth, plants have evolved strategies to integrate environmental signals to coordinate complex developmental and defensive processes to cope with the changing surroundings. Under challenges, plants prioritize their defense over growth. This trade-off involves complex interactions between multiple hormonal pathways and developmental networks. We discovered that JACKDAW (JKD), the core component of the SHORTROOT (SHR)-SCARECROW (SCR)- JKD plant developmental regulatory network is linking defense responses to the developmental programming. Unlike the well-studied function of JKD in root development, its function in leaves is yet to be understood. We found that JKD is expressed on the abaxial side of the leaf ground tissue. It has conserved functions in promoting SHR nuclear retention and restricting cyclinD6 expression in the leaf. Additionally, JKD has a function in leaf internal architecture establishment, including suppression of the bundle sheath cell division and shaping of the leaf ground tissue. We also found that SHR is a universal asymmetric cell division (ACD) activator, as ectopic SHR expression in the leaf ground tissue promotes stomata development via promoting the ACD to produce more stomata precursor cells. We showed that the knockout mutant of JKD has larger rosettes and better photosynthesis capacity, while the basal defense level and resistance to Botrytis cinerea, a necrotrophic pathogen, are enhanced. Our transcriptome and transcription studies revealed that JKD suppresses the expression of the plant defense hormone Jasmonic acid (JA) response genes and is itself downregulated by JA. This suggests that JKD is involved in the JA signaling, which mediates defense responses for wounding and herbivore attacks. Together, our study indicates that the loss of JKD uncoupled the plant growth-defense trade-off. JKD is a new link between plant development and defense. To verify whether this function of JKD is conserved in crops, JKD orthologues in tomatoes are identified, CRISPR-Cas9 and TILLING mutants are created and analyzed. The results showed that the functions of JKD in root development and resistance to botrytis are conserved. The broad presence of JKD orthologs makes them a great target for molecular breeding to generate crops that do not have to sacrifice their normal growth to defense response.