Plants live in fixed locations and survive adversity by integrating growth responses to diverse environmental signals. Here, we show that the nuclear-localized growth-repressing DELLA proteins of Arabidopsis integrate responses to independent hormonal and environmental signals of adverse conditions. The growth restraint conferred by DELLA proteins is beneficial and promotes survival. We propose that DELLAs permit flexible and appropriate modulation of plant growth in response to changes in natural environments.

Metabolomics studies generate increasingly complex data tables, which are hard to summarize and visualize without appropriate tools. The use of chemometrics tools, e.g., principal component analysis (PCA), partial least-squares to latent structures (PLS), and orthogonal PLS (OPLS), is therefore of great importance as these include efficient, validated, and robust methods for modeling information-rich chemical and biological data. Here the S-plot is proposed as a tool for visualization and interpretation of multivariate classification models, e.g., OPLS discriminate analysis, having two or more classes. The S-plot visualizes both the covariance and correlation between the metabolites and the modeled class designation. Thereby the S-plot helps identifying statistically significant and potentially biochemically significant metabolites, based both on contributions to the model and their reliability. An extension of the S-plot, the SUS-plot (shared and unique structure), is applied to compare the outcome of multiple classification models compared to a common reference, e.g., control. The used example is a gas chromatography coupled mass spectroscopy based metabolomics study in plant biology where two different transgenic poplar lines are compared to wild type. By using OPLS, an improved visualization and discrimination of interesting metabolites could be demonstrated.

of lowering LDL-C with statins alone vs statins plus ezetimibe on common CIMT in patients with type 2 diabetes and no known prior cardiovascular events. The SANDS Trial was a randomized, open labeled, blinded to outcomes, 3-year trial examining the effects of aggressive goals for LDL-C (Յ70 mg/dL) non-high-density lipoprotein cholesterol (Ͻ100 mg/dL) and blood pressure (Ͻ115/75 mm Hg) reduction vs standard goals of Ͻ100 mg/dL, Ͻ130mg/dL, and Ͻ130/80 mm Hg, respectively, in 499 Native American patients with type 2 diabetes. The primary outcome was change in CIMT after 36 months of treatment.Ezetimibe is an antihyperlipidemic medication used to lower cholesterol levels. It acts by decreasing cholesterol absorption in the intestine and can be used alone or with other cholesterol-lowering medications. It is generally indicated for use when cholesterol levels cannot be controlled with statins alone.The authors compared CIMT levels for 36 months in diabetic individuals aged Ͼ40 years receiving statins plus ezetimibe vs statins alone. The CIMT changes in both aggressive subgroups were compared with changes in the standard subgroups. LDL-C was reduced by 31 mg/dL (range, 23-37 mg/dL) and 32 mg/dL (range, 27-38 mg/dL) in the aggressive group by statins plus ezetimibe and statins alone, respectively. This was compared with changes of 1 mg/dL (range Ϫ3 to 6 mg/dL) in the standard group vs both aggressive subgroups (P Ͻ .0001). Within the aggressive group, mean CIMT at 36 months regressed in the ezetimibe and nonezetimibe subgroups but progressed in the standard treatment arm (Ϫ0.025, Ϫ0.012, and 0.039 mm, respectively; P Ͻ .0001).Comment: CIMT is considered a marker of future cardiovascular risk and thus can serve as a short-term surrogate for potential long-term cardiovascular events. The current trial has, therefore, two potential significant implications. The first is that ezetimibe does not provide any advantage over a statin alone in reducing long-term cardiovascular risk. The results would therefore seem to confirm the Enhanced Trial (N Engl J Med 2008;358: 1431-43) of 720 patients with familial hypercholesterolemia where there was no statistically significant difference in the primary end point of mean increase in CIMT over 24 months in the patients treated with statins alone vs statin plus ezetimibe. The second point is that it does appear possible to actually reduce surrogate markers of future atherosclerosis by aggressively lowering cholesterol beyond standard target levels. In its early stages, atherosclerosis may be a reversible disease.

SummaryReverse transcription-polymerase chain reaction (RT-PCR) approaches have been used in a large proportion of transcriptome analyses published to date. The accuracy of the results obtained by this method strongly depends on accurate transcript normalization using stably

Gas chromatography-mass spectrometry based metabolite profiling of biological samples is rapidly becoming one of the cornerstones of functional genomics and systems biology. Thus, the technology needs to be available to many laboratories and open exchange of information is required such as those achieved for transcript and protein data. The key-step in metabolite profiling is the unambiguous identification of metabolites in highly complex metabolite preparations with composite structure. Collections of mass spectra, which comprise frequently observed identified and non-identified metabolites, represent the most effective means to pool the identification efforts currently performed in many laboratories around the world. Here, we describe a platform for mass spectral and retention time index libraries that will enable this process (MSRI; www.csbdb.mpimpgolm.mpg.de/gmd.html). This resource should ameliorate many of the problems that each laboratory will face both for the initial establishment of metabolome analysis and for its maintenance at a constant sample throughput.

In most tree-breeding programs worldwide, increasing the trees' growth rates and stem volumes and shortening their rotation times are important aims. Such trees would yield more biomass per unit area. Here we show that overexpressing a key regulatory gene in the biosynthesis of the plant hormone gibberellin (GA) in hybrid aspen (Populus tremula x P. tremuloides) improves growth rate and biomass. In addition, these transgenic trees have more numerous and longer xylem fibers than unmodified wild-type (wt) plants. Long fibers are desirable in the production of strong paper, but it has not as yet proved possible to influence this trait by traditional breeding techniques. We also show that GA has an antagonistic effect on root initiation, as the transgenic lines showed poorer rooting than the control plants when potted in soil. However, the negative effect on rooting efficiencies in the initial establishment of young plantlets in the growth chamber did not significantly affect root growth at later stages.

No abstract

Local concentration gradients of the plant growth regulator auxin (indole-3-acetic acid [IAA]) are thought to instruct the positioning of organ primordia and stem cell niches and to direct cell division, expansion, and differentiation. Highresolution measurements of endogenous IAA concentrations in support of the gradient hypothesis are required to substantiate this hypothesis. Here, we introduce fluorescence-activated cell sorting of green fluorescent protein-marked cell types combined with highly sensitive mass spectrometry methods as a novel means for analyses of IAA distribution and metabolism at cellular resolution. Our results reveal the presence of IAA concentration gradients within the Arabidopsis thaliana root tip with a distinct maximum in the organizing quiescent center of the root apex. We also demonstrate that the root apex provides an important source of IAA and that cells of all types display a high synthesis capacity, suggesting a substantial contribution of local biosynthesis to auxin homeostasis in the root tip. Our results indicate that local biosynthesis and polar transport combine to produce auxin gradients and maxima in the root tip.