All living cells possess adaptive responses to environmental stress that are essential to ensuring cell survival. For motile organisms, this can culminate in avoidance or attractile behavior, but for sessile organisms such as plants, stress adaptation is a process of success or failure within the confines of a given environment. Nearly all bacterial species possess a highly evolved system for stress adaptation, known as the "stringent response." This ancient and ubiquitous regulatory response is mediated by production of a second messenger of general stress, the nucleotide guanosine-3 ,5 -(bis)pyrophosphate (ppGpp), which mediates reprogramming of the global transcriptional output of the cell. Accumulation of ppGpp is stress-induced through the enzymatic activation of the well known bacterial ppGpp synthetases, RelA and SpoT. We have recently discovered homologues of bacterial relA/spoT genes in the model plant Nicotiana tabacum. We hypothesize that these homologues (designated RSH genes for RelA/SpoT homologues) serve a stress-adaptive function in plants analogous with their function in bacteria. In support of this hypothesis, we find 1) inducibility of tobacco RSH gene expression following treatment with jasmonic acid; 2) bona fide ppGpp synthesis activity of purified recombinant Nt-RSH2 protein, and 3) a wide spread distribution of RSH gene expression in the plant kingdom. Phylogenetic analyses identifies a distinct phylogenetic branch for the plant RSH proteins with two subgroups and supports ancient symbiosis and nuclear gene transfer as a possible origin for these stress response genes in plants. In addition, we find that Nt-RSH2 protein co-purifies with chloroplasts in subcellular fractionation experiments. Taken together, our findings implicate a direct mode of action of these ppGpp synthetases with regard to plant physiology, namely regulation of chloroplast gene expression in response to plant defense signals.The relA and spoT genes in bacteria encode enzymes that synthesize the unusual nucleotide guanosine-3Ј,5Ј-(bis)pyrophosphate (ppGpp), 1 which is a second messenger of the socalled "stringent response" to nutrient deprivation and environmental stress. ppGpp is the intracellular effector of the stringent response, which acts by binding directly to and inducing allosteric modification of the bacterial RNA polymerase (RNAP) (1). This results in global reprogramming of the bacterium's transcriptional activity. There is a general inhibition of transcription and halting of the production of components of the protein synthesis apparatus in order to conserve energy. Simultaneously, there is an induction of stress genes to ensure proper cell adaptation and survival (2). Until recently, it was believed that the stringent response was limited to the bacterial domain of the prokaryote kingdom; however, plant homologues to these bacterial stress enzymes were recently identified (3, 4). In Arabidopsis thaliana, a relA/spoT homologue At-RSH1 was discovered in a yeast two-hybrid system using a disease resistance p...

Gene copy number (CN) variation is known to be important in nearly every species where it has been examined. Alterations in gene CN may provide a fast way of acquiring diversity, allowing rapid adaptation under strong selective pressures, and may also be a key component of standing genetic variation within species. Cannabis sativa plants produce a distinguishing set of secondary metabolites, the cannabinoids, many of which have medicinal utility. Two major cannabinoids—THCA (delta-9-tetrahydrocannabinolic acid) and CBDA (cannabidiolic acid)—are products of a three-step biochemical pathway. Using whole-genome shotgun sequence data for 69 Cannabis cultivars from diverse lineages within the species, we found that genes encoding the synthases in this pathway vary in CN. Transcriptome sequence data show that the cannabinoid paralogs are differentially expressed among lineages within the species. We also found that CN partially explains variation in cannabinoid content levels among Cannabis plants. Our results demonstrate that biosynthetic genes found at multiple points in the pathway could be useful for breeding purposes, and suggest that natural and artificial selection have shaped CN variation. Truncations in specific paralogs are associated with lack of production of particular cannabinoids, showing how phytochemical diversity can evolve through a complex combination of processes.

We have used micrococcal nuclease (MNase) digestion followed by deep sequencing in order to obtain a higher resolution map than previously available of nucleosome positions in the fission yeast, Schizosaccharomyces pombe. Our data confirm an unusually short average nucleosome repeat length, ∼152 bp, in fission yeast and that transcriptional start sites (TSSs) are associated with nucleosome-depleted regions (NDRs), ordered nucleosome arrays downstream and less regularly spaced upstream nucleosomes. In addition, we found enrichments for associated function in four of eight groups of genes clustered according to chromatin configurations near TSSs. At replication origins, our data revealed asymmetric localization of pre-replication complex (pre-RC) proteins within large NDRs—a feature that is conserved in fission and budding yeast and is therefore likely to be conserved in other eukaryotic organisms.

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BackgroundStudies of nuclear function in many organisms, especially those with tough cell walls, are limited by lack of availability of simple, economical methods for large-scale preparation of clean, undamaged nuclei.FindingsHere we present a useful method for nuclear isolation from the important model organism, the fission yeast, Schizosaccharomyces pombe. To preserve in vivo molecular configurations, we flash-froze the yeast cells in liquid nitrogen. Then we broke their tough cell walls, without damaging their nuclei, by grinding in a precision-controlled motorized mortar-and-pestle apparatus. The cryo-ground cells were resuspended and thawed in a buffer designed to preserve nuclear morphology, and the nuclei were enriched by differential centrifugation. The washed nuclei were free from contaminating nucleases and have proven well-suited as starting material for genome-wide chromatin analysis and for preparation of fragile DNA replication intermediates.ConclusionsWe have developed a simple, reproducible, economical procedure for large-scale preparation of endogenous-nuclease-free, morphologically intact nuclei from fission yeast. With appropriate modifications, this procedure may well prove useful for isolation of nuclei from other organisms with, or without, tough cell walls.

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Background Cannabis sativa is a primarily dioecious angiosperm that exhibits sexual developmental plasticity. Developmental genes for staminate male flowers have yet to be elucidated; however, there are regions of male-associated DNA from Cannabis (MADC) that correlate with the formation of pollen producing staminate flowers. MADC2 is an example of a PCR-based genetic marker that has been shown to produce a 390-bp amplicon that correlates with the expression of male phenotypes. We demonstrate applications of a cost-effective high-throughput male genotyping assay and other genotyping applications of male identification in Cannabis sativa. Methods In this study, we assessed data from 8200 leaf samples analyzed for real-time quantitative polymerase chain reaction (qPCR) detection of MADC2 in a commercial testing application offered through Steep Hill Laboratories. Through validation, collaborative research projects, and follow-up retest analysis, we observed a > 98.5% accuracy of detection of MADC2 by qPCR. We also carried out assay development for high-resolution melting analysis (HRM), loop-mediated isothermal amplification (LAMP), and TwistDx recombinase amplification (RPA) assays using MADC2 for male identification. Results We demonstrate a robust high-throughput duplex TaqMan qPCR assay for identification of male-specific genomic signatures using a novel MADC2 qPCR probe. The qPCR cycle quotient (Cq) value representative of MADC2 detection in 3156 males and the detection of tissue control cannabinoid synthesis for 8200 samples and the absence of MADC2 detection in 5047 non-males demonstrate a robust high-throughput real-time genotyping assay for Cannabis. Furthermore, we also demonstrated the viability of using nearby regions to MADC2 with novel primers as alternative assays. Finally, we also show proof of concept of several additional commercially viable sex determination methodologies for Cannabis sativa. Discussion In industrial applications, males are desirable for their more rapid growth and higher quality fiber quality, as well as their ability to pollinate female plants and produce grain. In medicinal applications, female cultivars are more desirable for their ability to produce large amounts of secondary metabolites, specifically the cannabinoids, terpenes, and flavonoids that have various medicinal and recreational properties. In previous studies, traditional PCR and non-high-throughput methods have been reported for the detection of male cannabis, and in our study, we present multiple methodologies that can be carried out in high-throughput commercial cannabis testing. Conclusion With these markers developed for high-throughput testing assays, the Cannabis industry will be able to easily screen and select for the desired sex of a given cultivar depending on the application.