Project description:In Arabidopsis, an individually darkened leaf (IDL) initiates senescence much quicker than a leaf from an entirely darkened plant (DP). In this study, we analysed the transcriptomes of leaves in these two darkening setups, to identify the differing metabolic strategies utilised that lead to such different fates.
Project description:Plants grow continuously and undergo numerous changes in their vegetative morphology and physiology during their life span. The molecular basis of these changes is largely unknown. To provide a more comprehensive picture of shoot development in Arabidopsis, microarray analysis was used to profile the mRNA content of shoot apices of different ages, as well as leaf primordia and fully-expanded leaves from 6 different positions on the shoot, in early-flowering and late-flowering genotypes. This extensive dataset provides a new and unexpectedly complex picture of shoot development in Arabidopsis. At any given time, the pattern of gene expression is different in every leaf on the shoot, and reflects the activity at least 6 developmental programs. Three of these are specific to individual leaves (leaf maturation, leaf aging, leaf senescence), two occur at the level of the shoot apex (vegetative phase change, floral induction), and one involves the entire shoot (shoot aging). Our results demonstrate that vegetative development is a much more dynamic process that previously imagined, and provide new insights into the underlying mechanism of this process.
Project description:Plant respiration responses to elevated growth [CO2] are key uncertainties in predicting future crop and ecosystem function. In particular, the effects of elevated growth [CO2] on respiration over leaf development are poorly understood. This study tested the prediction that, due to greater whole-plant photoassimilate availability and growth, elevated [CO2] induces transcriptional reprogramming and a stimulation of nighttime respiration in leaf primordia, expanding leaves, and mature leaves of Arabidopsis thaliana. In primordia, elevated [CO2] altered transcript abundance, but not for genes encoding respiratory proteins. In expanding leaves, elevated [CO2] induced greater glucose content and transcript abundance for some respiratory genes, but did not alter respiratory CO2 efflux. In mature leaves, elevated [CO2] led to greater glucose, sucrose and starch content, plus greater transcript abundance for many components of the respiratory pathway, and greater respiratory CO2 efflux. Therefore, growth at elevated [CO2] stimulated dark respiration only after leaves transitioned from carbon sinks into carbon sources. This coincided with greater photoassimilate production by mature leaves under elevated [CO2] and peak respiratory transcriptional responses. It remains to be determined if biochemical and transcriptional responses to elevated [CO2] in primordial and expanding leaves are essential prerequisites for subsequent alterations of respiratory metabolism in mature leaves.
Project description:The goal of this project is to compare the primary metabolite profile in different tissue types of the model plant Arabidopsis thaliana. Specifically, plants were grown hydroponically under the long-day (16hr light/day) condition at 21C. Tissue samples, including leaves, inflorescences, and roots were harvest 4 1/2 weeks post sowing. Untargeted primary metabolites profiling was carried out using GCTOF.
Project description:Microarrays were used to evaluate the effect of sucrose on gene expression in guard cells. Strips of Arabidopsis leaves were incubated with sucrose or mannitol or no sugars, then the leaves were freeze dried and guard cells were dissected from the leaf strips and analyzed.
Project description:The growth of plant organs is driven by cell division and subsequent cell expansion. The transition from proliferation into expansion is critical for the final organ size and, consequently plant yield. Exit from proliferation and onset of expansion is accompanied by major metabolic reprogramming, and in leaves with the establishment of photosynthesis. To learn more about the molecular mechanisms underlying the developmental and metabolic transitions important for plant growth, we used untargeted proteomics and metabolomics analyses to profile young leaves of a model plant Arabidopsis thaliana representing proliferation, transition, and expansion stages. The third true leaves of the in vitro grown Arabidopsis seedlings were harvested daily from day 8 to day 13 after stratification (8 to 13 DAS). Days 8 and 9 correspond to proliferation, days 12 and 13 to expansion and days 10 and 11 to the transition. The dataset presented represents a unique resource comprising approximately 4000 proteins and 300 annotated small-molecular compounds measured across six consecutive days of leaf growth. These can now be mined for novel developmental and metabolic regulators of plant growth and can act as a blueprint for future studies aimed at better defining the interface of development and metabolism in any other species.
Project description:Plants adapt to the prevailing photoperiod by optimally adjusting growth and flowering to the availability of energy. When Arabidopsis thaliana plants are grown in long days individual leaf growth is favoured, whereas whole plant leaf area is decreased because of the rapid shift to floral stages and, consequently, the low number of total leaves. To understand the molecular profiles of adaptation to long-day conditions we profiled Arabidopsis leaf number six of plants grown in 16 hours of light at four developmental stages both at the end of the day and the end of the night and compared the profiles to those acquired in short day conditions.
Project description:Plant respiration responses to elevated growth [CO2] are key uncertainties in predicting future crop and ecosystem function. In particular, the effects of elevated growth [CO2] on respiration over leaf development are poorly understood. This study tested the prediction that, due to greater whole-plant photoassimilate availability and growth, elevated [CO2] induces transcriptional reprogramming and a stimulation of nighttime respiration in leaf primordia, expanding leaves, and mature leaves of Arabidopsis thaliana. In primordia, elevated [CO2] altered transcript abundance, but not for genes encoding respiratory proteins. In expanding leaves, elevated [CO2] induced greater glucose content and transcript abundance for some respiratory genes, but did not alter respiratory CO2 efflux. In mature leaves, elevated [CO2] led to greater glucose, sucrose and starch content, plus greater transcript abundance for many components of the respiratory pathway, and greater respiratory CO2 efflux. Therefore, growth at elevated [CO2] stimulated dark respiration only after leaves transitioned from carbon sinks into carbon sources. This coincided with greater photoassimilate production by mature leaves under elevated [CO2] and peak respiratory transcriptional responses. It remains to be determined if biochemical and transcriptional responses to elevated [CO2] in primordial and expanding leaves are essential prerequisites for subsequent alterations of respiratory metabolism in mature leaves. Arabidopsis plants were grown in either ambient (370 ppm) or elevated (750 ppm) CO2. Leaf number 10 was harvested when it was a primordia, expanding, or mature in each of the CO2 treatments.