There are currently more than 1700 gene banks in the world today, all dedicated to ex situ conservation of plant diversity. Most of these are seed banks applying conventional storage protocols in which seeds are placed in a freezer at -20C. Such conservation efforts hinge on seed survival following extreme desiccation. However, seed responses to drying vary considerably among species, and those species producing seeds that are intolerant to desiccation (i.e., ‘recalcitrant’ response) are excluded from most seed banking programs. This seed trait, exhibited in several palms and cycads, and many tree species, is most frequent in tropical rainforests, a habitat that is both under threat from deforestation and home to about half the world’s flowering plants. Hence, there is an urgent need for non-conventional methods to preserve diversity of tropical plants. Alternative, innovative approaches use ultra-low temperature (i.e., cryopreservation). Another group of tropical and subtropical species produce seeds that tolerate partial drying but tend to age rapidly under conditions used in conventional seed banks. These species include important commodities (e.g., coffee, neem, tea), fruits (e.g., citrus, papaya) and ornamentals (e.g., orchids, Anthurium). Cryopreservation is also the only option to preserve diversity of these species. The purpose of this symposium is to explore current understanding of the factors that contribute to successful seed and tissue cryopreservation such as control of intracellular water relations, permeation of cryoprotective chemicals and retention of cell structural integrity. Using case studies on tropical biodiversity, the importance of multidisciplinary approaches that combine biochemistry, biophysics, microscopy will be highlighted and areas for future research needs will be identified.
A limiting factor is a factor that controls a process. Light intensity, temperature and carbon dioxide concentration are all factors which can control the rate of photosynthesis. Usually, only one of these factors will be the limiting factor in a plant at a certain time. This is the factor which is the furthest from its optimum level at a particular point in time. If we change the limiting factor the rate of photosynthesis will change but changes to the other factors will have no effect on the rate. If the levels of the limiting factor increase so that this factor is no longer the furthest from its optimum level, the limiting factor will change to the factor which is at that point in time, the furthest from its optimum level. For example, at night the limiting factor is likely to be the light intensity as this will be the furthest from its optimum level. During the day, the limiting factor is likely to switch to the temperature or the carbon dioxide concentration as the light intensity increases.
Describe the roles of photosynthesis and respiration in ..
The drawback to C4 photosynthesis is the extra energy in the form of that is used to pump the 4-carbon acids to the bundle sheath cell and the pumping of the 3-carbon compound back to the mesophyll cell for conversion to PEP. This loss to the system is why C3 plants will outperform C4 plants if there is a lot of water and sun. The C4 plants make some of that energy back in the fact that the rubisco is optimally used and the plant has to spend less energy synthesizing rubisco.
Temperature plays a role in affecting the rate of photosynthesis.
Plant evolutionary biologists have long appreciated the role of key innovations, such as nectar spurs, in the diversification of flowering plants. Recent evidence suggests that chemical features of flowers – their scent, nectar, pollen and oils - play important roles in the spectrum of generalized to specialized relationships with pollinators. These roles include the structuring of plant-pollinator community networks through pollinator attraction and repellence, innate pollinator preference in specialized reward-based systems, partner choice in obligate mutualism and sensory exploitation in deceptive pollination. Improved methods in chemical analysis, combined with new statistical, genomic and phylogenetic approaches, make it possible to combine chemical ecological methods with the study of diversification in species-rich angiosperm lineages (e.g. orchids, figs, Araceae, Phyllanthaceae). This symposium will showcase the state of the art of these combined chemical ecological and comparative approaches, to explore the potential for floral chemical traits to function as key innovations in the diversification of angiosperm lineages. Southern China is an inspiring place to discuss such a topic, with botanical diversity across all of its biomes and emerging local research on chemical aspects of pollination.
The thylakoid membranes are the site of the photosynthetic light ..
Animals do not always deliver pollen grains to recipient flowers of the same species. Interspecific pollen transfer (IPT) is a potential force in several contexts, including (1) the evolution of isolating barriers in speciation, (2) the interplay between competition/facilitation when co-occurring plant species share pollinators, (3) the potential physiological effects of allelopathic pollen on female reproductive success, (4) the loss of fitness through male function, and (5) the possible role in species interactions that govern plant community assembly or disassembly, including invasive species and phenological shifts. Over the last 40 years, such phenomena have received attention in scattered studies, but there has been a recent resurgence, as a number of young investigators have converged—from all of the above directions—to identify IPT as a primary object of study. The time is ripe for a symposium that will critically look backward and forward. Looking backward will help place current questions in a historical context and revise some incorrect or superficial impressions that show signs of taking root. Looking forward will help establish an agenda for further research. Expected participants include: Nathan Muchhala, Gerardo Arceo-Gomez, Robin Hopkins, Tia-Lynn Ashman, Shuang-Quan Huang, James Thomson