non-aqueous-isolation-enrichment-glandular-capitate-stalked-sessile

Non-Aqueous Isolation and Enrichment of Glandular Capitate Stalked and Sessile Trichomes from <em>Cannabis sativa</em>

This paper presents a protocol for the convenient and high-throughput isolation and enrichment of glandular capitate stalked and sessile trichomes from ...

ARO- Volcani Center

One of the approaches for conducting genomics research in organisms without extant microarray platforms is to profile their expression patterns by using Cross-Species Hybridization (CSH). Several different studies using spotted microarray and CSH produced contradicting conclusions in the ability of CSH to reflect biological processes described by species-specific hybridization (SSH).

Derivation of species-specific hybridization-like knowledge out of cross-species hybridization results.

The use of cross-species hybridization (CSH) to DNA microarrays, in which the target RNA and microarray probe are from different species, has increased in the past few years. CSH is used in comparative, evolutionary and ecological studies of closely related species, and for gene-expression profiling of many species that lack a representative microarray platform. However, unlike species-specific hybridization, CSH is still considered a non-standard use of microarrays. Here, we present the recent developments in the field of CSH for cDNA and oligomer microarray platforms. We discuss issues that influence the quality of CSH results, including platform choice, experiment design and data analysis, and suggest strategies that can lead to improvement of CSH studies to investigate species diversity.

Cross-species microarray hybridizations: a developing tool for studying species diversity.

Cross-species hybridization (CSH), i.e., the hybridization of a (target) species RNA to a DNA microarray that represents another (reference) species, is often used to study species diversity. However, filtration of CSH data has to be applied to extract valid information. We present a novel approach to filtering the CSH data, which utilizes spot characteristics (SCs) of image-quantification data from scanned spotted cDNA microarrays. Five SCs that were affected by sequence similarity between probe and target sequences were identified (designated as BS-SCs). Filtration by all five BS-SC thresholds demonstrated improved clustering for two of the three examined experiments, suggesting that BS-SCs may serve for filtration of data obtained by CSH, to improve the validity of the results. This CSH data-filtration approach could become a promising tool for studying a variety of species, especially when no genomic information is available for the target species.

Utilizing microarray spot characteristics to improve cross-species hybridization results.

Microarray-hybridization specificity is one of the main effectors of microarray result quality. In the present review, we suggest a definition for specificity that spans four hybridization levels, from the single probe to the microarray platform. For increased hybridization specificity, it is important to quantify the extent of the specificity at each of these levels, and correct the data accordingly. We outline possible effects of low hybridization specificity on the obtained results and list possible effectors of hybridization specificity. In addition, we discuss several studies in which theoretical approaches, empirical means or data filtration were used to identify specificity effectors, and increase the specificity of the hybridization results. However, these various approaches may not yet provide an ultimate solution; rather, further tool development is needed to enhance microarray-hybridization specificity.

Specificity of DNA microarray hybridization: characterization, effectors and approaches for data correction.

Strigolactones are considered a new group of plant hormones. Their role as modulators of plant growth and signalling molecules for plant interactions first became evident in Arabidopsis, pea, and rice mutants that were flawed in strigolactone production, release, or perception. The first evidence in tomato (Solanum lycopersicon) of strigolactone deficiency is presented here. Sl-ORT1, previously identified as resistant to the parasitic plant Orobanche, had lower levels of arbuscular mycorrhizal fungus (Glomus intraradices) colonization, possibly as a result of its reduced ability to induce mycorrhizal hyphal branching. Biochemical analysis of mutant root extracts suggested that it produces only minute amounts of two of the tomato strigolactones: solanacol and didehydro-orobanchol. Accordingly, the transcription level of a key enzyme (CCD7) putatively involved in strigolactone synthesis in tomato was reduced in Sl-ORT1 compared with the wild type (WT). Sl-ORT1 shoots exhibited increased lateral shoot branching, whereas exogenous application of the synthetic strigolactone GR24 to the mutant restored the WT phenotype by reducing the number of lateral branches. Reduced lateral shoot branching was also evident in grafted plants which included a WT interstock, which was grafted between the mutant rootstock and the scion. In roots of these grafted plants, the CCD7 transcription level was not significantly induced, nor was mycorrhizal sensitivity restored. Hence, WT-interstock grafting, which restores mutant shoot morphology to WT, does not restore mutant root properties to WT. Characterization of the first tomato strigolactone-deficient mutant supports the putative general role of strigolactones as messengers of suppression of lateral shoot branching in a diversity of plant species.

A tomato strigolactone-impaired mutant displays aberrant shoot morphology and plant interactions.

Strigolactones (SLs) have been recently identified as a new group of plant hormones or their derivatives thereof, shown to play a role in plant development. Evolutionary forces have driven the development of mechanisms in plants that allow adaptive adjustments to a variety of different habitats by employing plasticity in shoot and root growth and development. The ability of SLs to regulate both shoot and root development suggests a role in the plant's response to its growth environment. To play this role, SL pathways need to be responsive to plant growth conditions, and affect plant growth toward increased adaptive adjustment. Here, the effects of SLs on shoot and root development are presented, and possible feedback loops between SLs and two environmental cues, light and nutrient status, are discussed; these might suggest a role for SLs in plants' adaptive adjustment to growth conditions.

Strigolactones as mediators of plant growth responses to environmental conditions.

Tomato (Solanum lycopersicum) fruits expressing a yeast S-adenosyl methionine decarboxylase (ySAMdc) gene under control of a ripening-induced promoter show altered phytonutrient content and broad changes in gene expression. Genome-wide transcriptional alterations in pericarp tissues of the ySAMdc-expressing fruits are shown. Consistent with the ySAMdc expression pattern from the ripening-induced promoter, very minor transcriptional alterations were detected at the mature green developmental stage. At the breaker and red stages, altered levels of numerous transcripts were observed with a general tendency toward upregulation in the transgenic fruits. Ontological analysis of up- and downregulated transcript groups revealed various affected metabolic processes, mainly carbohydrate and amino acid metabolism, and protein synthesis, which appeared to be intensified in the ripening transgenic fruits. Other functional ontological categories of altered transcripts represented signal transduction, transcription regulation, RNA processing, molecular transport and stress response, as well as metabolism of lipids, glycans, xenobiotics, energy, cofactors and vitamins. In addition, transcript levels of genes encoding structural enzymes for several biosynthetic pathways showed strong correlations to levels of specific metabolites that displayed altered levels in transgenic fruits. Increased transcript levels of fatty acid biosynthesis enzymes were accompanied by a change in the fatty acid profile of transgenic fruits, most notably increasing ω-3 fatty acids at the expense of other lipids. Thus, SAMdc is a prime target in manipulating the nutritional value of tomato fruits. Combined with analyses of selected metabolites in the overripe fruits, a model of enhanced homeostasis of the pericarp tissue in the polyamine-accumulating tomatoes is proposed.

Expressing yeast SAMdc gene confers broad changes in gene expression and alters fatty acid composition in tomato fruit.

Strigolactones (SLs) are a novel class of plant hormones. Previously, we found that analogs of SLs induce growth arrest and apoptosis in breast cancer cell lines. These compounds also inhibited the growth of breast cancer stem cell enriched-mammospheres with increased potency. Furthermore, strigolactone analogs inhibited growth and survival of colon, lung, prostate, melanoma, osteosarcoma and leukemia cancer cell lines. To further examine the anti-cancer activity of SLs in vivo, we have examined their effects on growth and viability of MDA-MB-231 tumor xenografts model either alone or in combination with paclitaxel. We show that strigolactone act as new anti-cancer agents in inhibition of breast cancer in xenograft model. In addition we show that SLs affect the integrity of the microtubule network and therefore may inhibit the migratory phenotype of the highly invasive breast cancer cell lines that were examined.

Strigolactone analogs act as new anti-cancer agents in inhibition of breast cancer in xenograft model.

Strigolactones (SLs) are new plant hormones with various developmental functions. They are also soil signaling chemicals that are required for establishing beneficial mycorrhizal plant/fungus symbiosis. In addition, SLs play an essential role in inducing seed germination in root-parasitic weeds, which are one of the seven most serious biological threats to food security. There are around 20 natural SLs that are produced by plants in very low quantities. Therefore, most of the knowledge on SL signal transduction and associated molecular events is based on the application of synthetic analogues. Stereochemistry plays a crucial role in the structure-activity relationship of SLs, as compounds with an unnatural D-ring configuration may induce biological effects that are unrelated to SLs. We have synthesized a series of strigolactone analogues, whose absolute configuration has been elucidated and related with their biological activity, thus confirming the high specificity of the response. Analogues bearing the R-configured butenolide moiety showed enhanced biological activity, which highlights the importance of this stereochemical motif.

Stereochemical Assignment of Strigolactone Analogues Confirms Their Selective Biological Activity.

MAX2/strigolactone signaling in the endodermis and/or quiescent center of the root is partially sufficient to exert changes in F-actin density and cellular trafficking in the root epidermis, and alter gene expression during plant response to low Pi conditions. Strigolactones (SLs) are a new group of plant hormones that regulate different developmental processes in the plant via MAX2, an F-box protein that interacts with their receptor. SLs and MAX2 are necessary for the marked increase in root-hair (RH) density in seedlings under conditions of phosphate (Pi) deprivation. This marked elevation was associated with an active reduction in actin-filament density and endosomal movement in root epidermal cells. Also, expression of MAX2 under the SCARECROW (SCR) promoter was sufficient to confer SL sensitivity in roots, suggesting that SL signaling pathways act through a root-specific, yet non-cell-autonomous regulatory mode of action. Here we show evidence for a non-cell autonomous signaling of SL/MAX2, originating from the root endodermis, and necessary for seedling response to conditions of Pi deprivation. SCR-derived expression of MAX2 in max2-1 mutant background promoted the root low Pi response, whereas supplementation of the synthetic SL GR24 to these SCR:MAX2 expressing lines further enhanced this response. Moreover, the SCR:MAX2 expression led to changes in actin density and endosome movement in epidermal cells and in TIR1 and PHO2 gene expression. These results demonstrate that MAX2 signaling in the endodermis and/or quiescent center is partially sufficient to exert changes in F-actin density and cellular trafficking in the epidermis, and alter gene expression under low Pi conditions.

Expression of MAX2 under SCARECROW promoter enhances the strigolactone/MAX2 dependent response of Arabidopsis roots to low-phosphate conditions.

The Mediterranean basin is one of the richest biodiversity areas in the world, and the use of medicinal plants for treating cancer in this area has been documented for generations in different cultures.

Article	Year
Derivation of species-specific hybridization-like knowledge out of cross-species hybridization results. BMC genomics\| PubMed ID: 16677401	2006
Cross-species microarray hybridizations: a developing tool for studying species diversity. Trends in genetics : TIG\| PubMed ID: 17313995	2007
Utilizing microarray spot characteristics to improve cross-species hybridization results. Genomics\| PubMed ID: 17888623	2007
Specificity of DNA microarray hybridization: characterization, effectors and approaches for data correction. Nucleic acids research\| PubMed ID: 18299281	2008
A tomato strigolactone-impaired mutant displays aberrant shoot morphology and plant interactions. Journal of experimental botany\| PubMed ID: 20194924	2010
Strigolactones as mediators of plant growth responses to environmental conditions. Plant signaling & behavior\| PubMed ID: 21248472	2011
Expressing yeast SAMdc gene confers broad changes in gene expression and alters fatty acid composition in tomato fruit. Physiologia plantarum\| PubMed ID: 21338368	2011
Strigolactone analogs act as new anti-cancer agents in inhibition of breast cancer in xenograft model. Cancer biology & therapy\| PubMed ID: 26192476	2015
Stereochemical Assignment of Strigolactone Analogues Confirms Their Selective Biological Activity. Journal of natural products\| PubMed ID: 26502774	2015
Expression of MAX2 under SCARECROW promoter enhances the strigolactone/MAX2 dependent response of Arabidopsis roots to low-phosphate conditions. Planta\| PubMed ID: 26919985	2016
Review on Anti-Cancer Activity in Wild Plants of the Middle East. Current medicinal chemistry\| PubMed ID: 28685674	2018

Hinanit Koltai

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