Independent responses to ultraviolet radiation and herbivore attack in broccoli

The plant responses to ultraviolet-B radiation (UV-B) and to insect herbivory are believed to be partially similar. In this study, responses to these factors were investigated in the crop species broccoli (Brassica oleracea L. convar. botrytis, Brassicaceae). Plants were first grown under three UV-B regimes (80%, 23%, and 4% transmittance of ambient UV-B) in greenhouses covered with either innovative materials (high and medium transmittance) or conventional glass (low transmittance). Half of the plants then remained under these conditions, but the other half were transferred to the field with ambient light and herbivore access for up to 3 d. The plant responses to distinct environmental conditions were examined by analysing the morphological and chemical parameters of plants kept inside and plants exposed in the field. Furthermore, suitability of field-exposed plants to naturally occurring insects was investigated in relation to UV-B pretreatment. High levels of UV-B radiation led to increased flavonoid concentrations, but to a lower biomass accumulation in broccoli. These patterns remained after outdoor exposure. However, UV-induced changes of plant traits did not alter attractiveness to herbivorous insects: thrips, whiteflies, and aphids attacked plants independently of UV-B pretreatment. A 3-fold increase of indolyl glucosinolate concentrations occurred in above-ground tissue of all the plants, most likely due to massive herbivore attack after 3 d of field exposure. The results show that plants respond with high specificity to different abiotic and biotic impacts, demonstrating the separate perception and processing of stress factors

Genome-wide activity of unliganded estrogen receptor-\u3b1\ua0 in breast cancer cells

Estrogen receptor-\u3b1 (ER\u3b1) has central role in hormone-dependent breast cancer and its ligand-induced functions have been extensively characterized. However, evidence exists that ER\u3b1 has functions that are independent of ligands. In the present work, we investigated the binding of ER\u3b1 to chromatin in the absence of ligands and its functions on gene regulation. We demonstrated that in MCF7 breast cancer cells unliganded ER\u3b1 binds to more than 4,000 chromatin sites. Unexpectedly, although almost entirely comprised in the larger group of estrogen-induced binding sites, we found that unliganded-ER\u3b1 binding is specifically linked to genes with developmental functions, compared with estrogen-induced binding. Moreover, we found that siRNA-mediated down-regulation of ER\u3b1 in absence of estrogen is accompanied by changes in the expression levels of hundreds of coding and noncoding RNAs. Down-regulatedmRNAs showed enrichment in genes related to epithelial cell growth and development. Stable ER\u3b1 down-regulation using shRNA, which caused cell growth arrest, was accompanied by increased H3K27me3 at ER\u3b1 binding sites. Finally, we found that FOXA1 and AP2\u3b3 binding to several sites is decreased upon ER\u3b1 silencing, suggesting that unliganded ER\u3b1 participates, together with other factors, in the maintenance of the luminal-specific cistrome in breast cancer cell

Ozone depletion, ultraviolet radiation, climate change and prospects for a sustainable future

Changes in stratospheric ozone and climate over the past 40-plus years have altered the solar ultraviolet (UV) radiation conditions at the Earth's surface. Ozone depletion has also contributed to climate change across the Southern Hemisphere. These changes are interacting in complex ways to affect human health, food and water security, and ecosystem services. Many adverse effects of high UV exposure have been avoided thanks to the Montreal Protocol with its Amendments and Adjustments, which have effectively controlled the production and use of ozone-depleting substances. This international treaty has also played an important role in mitigating climate change. Climate change is modifying UV exposure and affecting how people and ecosystems respond to UV; these effects will become more pronounced in the future. The interactions between stratospheric ozone, climate and UV radiation will therefore shift over time; however, the Montreal Protocol will continue to have far-reaching benefits for human well-being and environmental sustainability.Peer reviewe

Network Analysis Identifies ELF3 as a QTL for the Shade Avoidance Response in Arabidopsis

Quantitative Trait Loci (QTL) analyses in immortal populations are a powerful method for exploring the genetic mechanisms that control interactions of organisms with their environment. However, QTL analyses frequently do not culminate in the identification of a causal gene due to the large chromosomal regions often underlying QTLs. A reasonable approach to inform the process of causal gene identification is to incorporate additional genome-wide information, which is becoming increasingly accessible. In this work, we perform QTL analysis of the shade avoidance response in the Bayreuth-0 (Bay-0, CS954) x Shahdara (Sha, CS929) recombinant inbred line population of Arabidopsis. We take advantage of the complex pleiotropic nature of this trait to perform network analysis using co-expression, eQTL and functional classification from publicly available datasets to help us find good candidate genes for our strongest QTL, SAR2. This novel network analysis detected EARLY FLOWERING 3 (ELF3; AT2G25930) as the most likely candidate gene affecting the shade avoidance response in our population. Further genetic and transgenic experiments confirmed ELF3 as the causative gene for SAR2. The Bay-0 and Sha alleles of ELF3 differentially regulate developmental time and circadian clock period length in Arabidopsis, and the extent of this regulation is dependent on the light environment. This is the first time that ELF3 has been implicated in the shade avoidance response and that different natural alleles of this gene are shown to have phenotypic effects. In summary, we show that development of networks to inform candidate gene identification for QTLs is a promising technique that can significantly accelerate the process of QTL cloning

Expression profiling during arabidopsis/downy mildew interaction reveals a highly-expressed effector that attenuates responses to salicylic acid

Plants have evolved strong innate immunity mechanisms, but successful pathogens evade or suppress plant immunity via effectors delivered into the plant cell. Hyaloperonospora arabidopsidis (Hpa) causes downy mildew on Arabidopsis thaliana, and a genome sequence is available for isolate Emoy2. Here, we exploit the availability of genome sequences for Hpa and Arabidopsis to measure gene-expression changes in both Hpa and Arabidopsis simultaneously during infection. Using a high-throughput cDNA tag sequencing method, we reveal expression patterns of Hpa predicted effectors and Arabidopsis genes in compatible and incompatible interactions, and promoter elements associated with Hpa genes expressed during infection. By resequencing Hpa isolate Waco9, we found it evades Arabidopsis resistance gene RPP1 through deletion of the cognate recognized effector ATR1. Arabidopsis salicylic acid (SA)-responsive genes including PR1 were activated not only at early time points in the incompatible interaction but also at late time points in the compatible interaction. By histochemical analysis, we found that Hpa suppresses SA-inducible PR1 expression, specifically in the haustoriated cells into which host-translocated effectors are delivered, but not in non-haustoriated adjacent cells. Finally, we found a highly-expressed Hpa effector candidate that suppresses responsiveness to SA. As this approach can be easily applied to host-pathogen interactions for which both host and pathogen genome sequences are available, this work opens the door towards transcriptome studies in infection biology that should help unravel pathogen infection strategies and the mechanisms by which host defense responses are overcome

Using Light to Improve Commercial Value

The plasticity of plant morphology has evolved to maximize reproductive fitness in response to prevailing environmental conditions. Leaf architecture elaborates to maximize light harvesting, while the transition to flowering can either be accelerated or delayed to improve an individual's fitness. One of the most important environmental signals is light, with plants using light for both photosynthesis and as an environmental signal. Plants perceive different wavelengths of light using distinct photoreceptors. Recent advances in LED technology now enable light quality to be manipulated at a commercial scale, and as such opportunities now exist to take advantage of plants' developmental plasticity to enhance crop yield and quality through precise manipulation of a crops' lighting regime. This review will discuss how plants perceive and respond to light, and consider how these specific signaling pathways can be manipulated to improve crop yield and quality