The wheat spikelet meristem differentiates into up to 12 floret primordia, but many of them fail to reach the fertile floret stage at anthesis. We combined microarray, biochemical and anatomical ...studies to investigate floret development in wheat plants grown in the field under short or long days (short days extended with low-fluence light) after all the spikelets had already differentiated. Long days accelerated spike and floret development and greening, and the expression of genes involved in photosynthesis, photoprotection and carbohydrate metabolism. These changes started while the spike was in the light-depleted environment created by the surrounding leaf sheaths. Cell division ceased in the tissues of distal florets, which interrupted their normal developmental progression and initiated autophagy, thus decreasing the number of fertile florets at anthesis. A massive decrease in the expression of genes involved in cell proliferation, a decrease in soluble carbohydrate levels, and an increase in the expression of genes involved in programmed cell death accompanied anatomical signs of cell death, and these effects were stronger under long days. We propose a model in which developmentally generated sugar starvation triggers floret autophagy, and long days intensify these processes due to the increased carbohydrate consumption caused by the accelerated plant development.
Cultivated tomato (Solanum lycopersicum L.) has narrow genetic diversity that makes it difficult to identify polymorphisms between elite germplasm. We explored array-based single feature polymorphism ...(SFP) discovery as a high-throughput approach for marker development in cultivated tomato.
Three varieties, FL7600 (fresh-market), OH9242 (processing), and PI114490 (cherry) were used as a source of genomic DNA for hybridization to oligonucleotide arrays. Identification of SFPs was based on outlier detection using regression analysis of normalized hybridization data within a probe set for each gene. A subset of 189 putative SFPs was sequenced for validation. The rate of validation depended on the desired level of significance (alpha) used to define the confidence interval (CI), and ranged from 76% for polymorphisms identified at alpha <or= 10-6 to 60% for those identified at alpha <or= 10-2. Validation percentage reached a plateau between alpha <or= 10-4 and alpha <or= 10-7, but failure to identify known SFPs (Type II error) increased dramatically at alpha <or= 10-6. Trough sequence validation, we identified 279 SNPs and 27 InDels in 111 loci. Sixty loci contained >or= 2 SNPs per locus. We used a subset of validated SNPs for genetic diversity analysis of 92 tomato varieties and accessions. Pairwise estimation of theta (Fst) suggested significant differentiation between collections of fresh-market, processing, vintage, Latin American (landrace), and S. pimpinellifolium accessions. The fresh-market and processing groups displayed high genetic diversity relative to vintage and landrace groups. Furthermore, the patterns of SNP variation indicated that domestication and early breeding practices have led to progressive genetic bottlenecks while modern breeding practices have reintroduced genetic variation into the crop from wild species. Finally, we examined the ratio of non-synonymous (Ka) to synonymous substitutions (Ks) for 20 loci with multiple SNPs (>or= 4 per locus). Six of 20 loci showed ratios of Ka/Ks >or= 0.9.
Array-based SFP discovery was an efficient method to identify a large number of molecular markers for genetics and breeding in elite tomato germplasm. Patterns of sequence variation across five major tomato groups provided insight into to the effect of human selection on genetic variation.
The Arabidopsis gene COI1 is required for jasmonic acid (JA)-induced growth inhibition, resistance to insect herbivory, and resistance to pathogens. In addition, COI1 is also required for ...transcription of several genes induced by wounding or by JA. Here, we use microarray gene transcription profiling of wild type and coi1 mutant plants to examine the extent of the requirement of COI1 for JA-induced and wound-induced gene transcription. We show that COI1 is required for expression of approximately 84% of 212 genes induced by JA, and for expression of approximately 44% of 153 genes induced by wounding. Surprisingly, COI1 was also required for repression of 53% of 104 genes whose expression was suppressed by JA, and for repression of approximately 46% of 83 genes whose expression was suppressed by wounding. These results indicate that COI1 plays a pivotal role in wound- and JA signalling.
Affymetrix GeneChips arrayed with about one-half (~23K) of the rice genes were used to profile gene transcription activity in three tissues comprising the maize root tip; the proximal meristem (PM), ...the quiescent center (QC), and the root cap (RC). Here we analyze the gene transcription profile of the RC, compared to both the PM and the QC, from three biological replicates. In the RC, a total of 669 genes were identified as being differentially upregulated, and 365 differentially downregulated. Real-time quantitative RT-PCR analysis was used to confirm upregulated genes in the RC. In addition, using the technique of laser microdissection (LMD) we localized upregulated gene expression to the lateral RC cells. Taken as a whole, transcription profile analyses revealed the upregulation in the maize RC of clusters of genes linked to major metabolic processes and pathways, including: (1) transport, both the export of carbohydrates and the uptake of nutrients; (2) sensing and responding to (often stressful) biotic and abiotic environmental stimuli; (3) integrating the responses of at least 3 major growth regulators (auxin, ethylene, jasmonic acid); (4) processing the large amount of carbohydrate transported into the RC. Although the profile data are derived using heterologous rice GeneChips, with about half of the total rice gene set, this study, nevertheless, provides a genomic scale characterization of the entire RC, and serves as a new platform from which to advance studies of the network of pathways operating in the maize RC.
Mass casualty decontamination is a public health intervention that would be employed by emergency responders following a chemical, biological, or radiological incident. The decontamination of large ...numbers of casualties is currently most often performed with water to remove contaminants from the skin surface. An online survey was conducted to explore US fire departments' decontamination practices and their preparedness for responding to incidents involving mass casualty decontamination. Survey respondents were asked to provide details of various aspects of their decontamination procedures, including expected response times to reach casualties, disrobing procedures, approaches to decontamination, characteristics of the decontamination showering process, provision for special populations, and any actions taken following decontamination. The aim of the survey was to identify any differences in the way in which decontamination guidance is implemented across US states. Results revealed that, in line with current guidance, many US fire departments routinely use the "ladder-pipe system" for conducting rapid, gross decontamination of casualties. The survey revealed significant variability in ladder-pipe construction, such as the position and number of fire hoses used. There was also variability in decontamination characteristics, such as water temperature and water pressure, detergent use, and shower duration. The results presented here provide important insights into the ways in which implementation of decontamination guidance can vary between US states. These inconsistencies are thought to reflect established perceived best practices and local adaptation of response plans to address practical and logistical constraints. These outcomes highlight the need for evidence-based national guidelines for conducting mass casualty decontamination.
Several hundred strains of Bacillus thuringiensis (Bt), isolated in New Zealand from samples of soil and sheep fleece, were tested for toxicity to larvae of the blowfly Lucilia cuprina Wiedemann. ...Characterization of the Bt strains revealed that three of the more active strains produced Cry1Ba (an insecticidal protein present in Bt mother cell crystal inclusion) that was toxic to blowflies. These strains were evaluated for the ability to prevent experimentally induced fly strike in a bioassay by using first instars. Results with undiluted spore/crystal preparations were variable, but they generally prevented fly strike on sheep maintained on pasture for 3–6 wk. Spore viability was satisfactory throughout the trials and environmental factors (e.g., precipitation and UV radiation) seemed to have minimal effect on persistence. The loss of fly strike protection in these experiments correlated with the movement of spore/crystal toxicity away from the skin as a result of wool growth. Solubilized protein preparations were not as potent as spore/crystal preparations and fly strike protection lasted only from 1 to 3 wk. Vegetative forms of the Cry1Ba-producing strains of Bt did not establish on the fleece of sheep, did not produce significant sporulation, and no protection against fly strike was achieved. Escherichia coli expressing recombinant Cry1Ba protein was toxic to larvae in vitro but did not effectively protect sheep from fly strike because blowfly larvae were able to establish readily 8 d posttreatment. In a single field experiment involving 80 sheep per group, a spore/crystal preparation from a Bt strain expressing Cry1Ba provided less protection from naturally acquired fly strike than afforded by a commercially available dip.
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