Improvement and transcriptome analysis of root architecture by overexpression of Fraxinus pennsylvanica DREB2A transcription factor in Robinia pseudoacacia L. 'Idaho'.

Transcription factors play a key role to enable plants to cope with abiotic stresses. DREB2 regulates the expression of several stress-inducible genes and constitutes major hubs in the water stress signalling webs. We cloned and characterized a novel gene encoding the FpDREB2A transcription factor from Fraxinus pennsylvanica, and a yeast activity assay confirmed its DRE binding and transcription activation. Overexpression of FpDREB2A in R. pseudoacacia showed enhanced resistance to drought stress. The transgenic plant survival rate was significantly higher than that of WT in soil drying and re-watering treatments. Transgenic lines showed a dramatic change in root architecture, and horizontal and vertical roots were found in transgenic plants compared to WT. The vertical roots penetrated in the field soil to more than 60 cm deep, while horizontal roots expanded within the top 20-30 cm of the soil. A physiological test demonstrated that chlorophyll contents were more gradually reduced and that soluble sugars and proline levels elevated more sharply but malondialdehyde level stayed the same (P < 0.05). Plant hormone levels of abscisic acid and IAA were higher than that of WT, while gibberellins and zeatin riboside were found to be lower. The root transcriptomes were sequenced and annotated into 2011 differential expression genes (DEGs). The DEGs were categorized in 149 pathways and were found to be involved in plant hormone signalling, transcription factors, stimulus responses, phenylalanine, carbohydrate and other metabolic pathways. The modified pathways in plant hormone signalling are thought to be the main cause of greater horizontal and vertical root development, in particular.

Microbial community structure and diversity in the soil spatial profile of 5-year-old Robinia pseudoacacia 'Idaho,' determined by 454 sequencing of the 16S RNA gene.

Relatively little information is available regarding the variability of microbial communities inhabiting deeper soil layers. We investigated the distribution of soil microbial communities down to 1.2 m in 5-year-old Robinia pseudoacacia 'Idaho' soil by 454 sequencing of the 16S RNA gene. The average number of sequences per sample was 12,802. The Shannon and Chao 1 indices revealed various relative microbial abundances and even distribution of microbial diversity for all evaluated sample depths. The predicted diversity in the topsoil exceeded that of the corresponding subsoil. The changes in the relative abundance of the major soil bacterial phyla showed decreasing, increasing, or no consistent trends with respect to sampling depth. Despite their novelty, members of the new candidate phyla OD1 and TM7 were widespread. Environmental variables affecting the bacterial community within the environment appeared to differ from those reported previously, especially the lack of detectable effect from pH. Overall, we found that the overall relative abundance fluctuated with the physical and chemical properties of the soil, root system, and sampling depth. Such information may facilitate forest soil management.

Ginkgo biloba use in nursing home elderly with epilepsy or seizure disorder.

PURPOSE: Ginkgo biloba, among the most widely used herbs, possesses the capacity both to induce and to inhibit seizures. The purpose of this study was to describe the prevalence of ginkgo and other common herb prescribing in a sample of nursing home (NH) elderly diagnosed with epilepsy/seizure (Epi/Sz) disorder and to determine demographic, clinical, and functional factors associated with ginkgo use. METHODS: This was a 1-year prevalence study of 68,403 NH residents living in 557 nursing facilities throughout the United States. RESULTS: Overall, herb use in the NHs was very low (0.41%). Ginkgo was prescribed 162 times, more than any other herb. St. John's wort was prescribed 40 times; garlic, 29 times; and all others, <20 times, for a total of 307 herb orders. Among all residents with an herb order, ginkgo was prescribed for 61.9% of residents with an Epi/Sz diagnosis and 58.0% (p = 0.820) of residents without an Epi/Sz diagnosis. Dementia, educational level, and the interaction of age group with cognitive impairment were all significantly associated with herb use among Epi/Sz residents. Cognitive impairment and the interaction of Epi/Sz disorder with dementia were associated specifically with ginkgo use. CONCLUSIONS: Ginkgo is the most frequently prescribed herb in this population in which >50% of all herb orders were written for ginkgo. The concern with ginkgo use among elderly with Epi/Sz is the lack of standardization that characterizes ginkgo products. In the absence of standardization, the likelihood is increased that ginkgo products may be adulterated with the Ginkgo biloba plant parts most commonly associated with seizure provocation.