Plant neighbor identity influences plant biochemistry and physiology related to defense

<p>Abstract</p> <p>Background</p> <p>Chemical and biological processes dictate an individual organism's ability to recognize and respond to other organisms. A small but growing body of evidence suggests that plants may be capable of recognizing and responding to neighboring plants in a species specific fashion. Here we tested whether or not individuals of the invasive exotic weed, <it>Centaurea maculosa</it>, would modulate their defensive strategy in response to different plant neighbors.</p> <p>Results</p> <p>In the greenhouse, <it>C. maculosa </it>individuals were paired with either conspecific (<it>C. maculosa</it>) or heterospecific (<it>Festuca idahoensis</it>) plant neighbors and elicited with the plant defense signaling molecule methyl jasmonate to mimic insect herbivory. We found that elicited <it>C. maculosa </it>plants grown with conspecific neighbors exhibited increased levels of total phenolics, whereas those grown with heterospecific neighbors allocated more resources towards growth. To further investigate these results in the field, we conducted a metabolomics analysis to explore chemical differences between individuals of <it>C. maculosa </it>growing in naturally occurring conspecific and heterospecific field stands. Similar to the greenhouse results, <it>C. maculosa </it>individuals accumulated higher levels of defense-related secondary metabolites and lower levels of primary metabolites when growing in conspecific versus heterospecific field stands. Leaf herbivory was similar in both stand types; however, a separate field study positively correlated specialist herbivore load with higher densities of <it>C. maculosa </it>conspecifics.</p> <p>Conclusions</p> <p>Our results suggest that an individual <it>C. maculosa </it>plant can change its defensive strategy based on the identity of its plant neighbors. This is likely to have important consequences for individual and community success.</p

Signaling Overview of Plant Somatic Embryogenesis

Somatic embryogenesis (SE) is a means by which plants can regenerate bipolar structures from a somatic cell. During the process of cell differentiation, the explant responds to endogenous stimuli, which trigger the induction of a signaling response and, consequently, modify the gene program of the cell. SE is probably the most studied plant regeneration model, but to date it is the least understood due to the unclear mechanisms that occur at a cellular level. In this review, the authors seek to emphasize the importance of signaling on plant SE, highlighting the interactions between the different plant growth regulators (PGR), mainly auxins, cytokinins (CKs), ethylene and abscisic acid (ABA), during the induction of SE. The role of signaling is examined from the start of cell differentiation through the early steps on the embryogenic pathway, as well as its relation to a plant’s tolerance of different types of stress. Furthermore, the role of genes encoded to transcription factors (TFs) during the embryogenic process such as the LEAFY COTYLEDON (LEC), WUSCHEL (WUS), BABY BOOM (BBM) and CLAVATA (CLV) genes, Arabinogalactan-proteins (AGPs), APETALA 2 (AP2) and epigenetic factors is discussed

5-Azacytidine: A Promoter of Epigenetic Changes in the Quest to Improve Plant Somatic Embryogenesis

Somatic embryogenesis (SE) is a widely studied process due to its biotechnological potential to generate large quantities of plants in short time frames and from different sources of explants. The success of SE depends on many factors, such as the nature of the explant, the microenvironment generated by in vitro culture conditions, and the regulation of gene expression, among others. Epigenetics has recently been identified as an important factor influencing SE outcome. DNA methylation is one of the most studied epigenetic mechanisms due to its essential role in gene expression, and its participation in SE is crucial. DNA methylation levels can be modified through the use of drugs such as 5-Azacytidine (5-AzaC), an inhibitor of DNA methylation, which has been used during SE protocols. The balance between hypomethylation and hypermethylation seems to be the key to SE success. Here, we discuss the most prominent recent research on the role of 5-AzaC in the regulation of DNA methylation, highlighting its importance during the SE process. Also, the molecular implications that this inhibitor might have for the increase or decrease in the embryogenic potential of various explants are reviewed

Stem Cells from Dental Pulp: What Epigenetics Can Do with Your Tooth

Adult stem cells have attracted scientific attention because they are able to self-renew and differentiate into several specialized cell types. In this context, human dental tissue-derived mesenchymal stem cells (hDT-MSCs) have emerged as a possible solution for repairing or regenerating damaged tissues. These cells can be isolated from primary teeth that are naturally replaced, third molars, or other dental tissues and exhibit self-renewal, a high proliferative rate and a great multilineage potential. However, the cellular and molecular mechanisms that determine lineage specification are still largely unknown. It is known that a change in cell fate requires the deletion of existing transcriptional programs, followed by the establishment of a new developmental program to give rise to a new cell lineage. Increasing evidence indicates that chromatin structure conformation can influence cell fate. In this way, reversible chemical modifications at the DNA or histone level, and combinations thereof can activate or inactivate cell-type-specific gene sequences, giving rise to an alternative cell fates. On the other hand, miRNAs are starting to emerge as a possible player in establishing particular somatic lineages. In this review, we discuss two new and promising research fields in medicine and biology, epigenetics and stem cells, by summarizing the properties of hDT-MSCs and highlighting the recent findings on epigenetic contributions to the regulation of cellular differentiation

<it>KNOX1</it> is expressed and epigenetically regulated during <it>in vitro</it> conditions in <it>Agave spp</it>

<p>Abstract</p> <p>Background</p> <p>The micropropagation is a powerful tool to scale up plants of economical and agronomical importance, enhancing crop productivity. However, a small but growing body of evidence suggests that epigenetic mechanisms, such as DNA methylation and histone modifications, can be affected under the <it>in vitro</it> conditions characteristic of micropropagation. Here, we tested whether the adaptation to different <it>in vitro</it> systems (Magenta boxes and Bioreactors) modified epigenetically different clones of <it>Agave fourcroydes</it> and <it>A. angustifolia</it>. Furthermore, we assessed whether these epigenetic changes affect the regulatory expression of <it>KNOTTED1</it>-like <it>HOMEOBOX</it> (<it>KNOX</it>) transcription factors.</p> <p>Results</p> <p>To gain a better understanding of epigenetic changes during <it>in vitro</it> and <it>ex vitro</it> conditions in <it>Agave fourcroydes</it> and <it>A. angustifolia</it>, we analyzed global DNA methylation, as well as different histone modification marks, in two different systems: semisolid in Magenta boxes (M) and temporary immersion in modular Bioreactors (B). No significant difference was found in DNA methylation in <it>A. fourcroydes</it> grown in either M or B. However, when <it>A. fourcroydes</it> was compared with <it>A. angustifolia,</it> there was a two-fold difference in DNA methylation between the species, independent of the <it>in vitro</it> system used. Furthermore, we detected an absence or a low amount of the repressive mark H3K9me2 in <it>ex vitro</it> conditions in plants that were cultured earlier either in M or B. Moreover, the expression of <it>AtqKNOX1</it> and <it>AtqKNOX2,</it> on <it>A. fourcroydes</it> and <it>A. angustifolia</it> clones, is affected during <it>in vitro</it> conditions. Therefore, we used Chromatin ImmunoPrecipitation (ChIP) to know whether these genes were epigenetically regulated. In the case of <it>AtqKNOX1,</it> the H3K4me3 and H3K9me2 were affected during <it>in vitro</it> conditions in comparison with <it>AtqKNOX2</it>.</p> <p>Conclusions</p> <p>Agave clones plants with higher DNA methylation during <it>in vitro</it> conditions were better adapted to <it>ex vitro</it> conditions. In addition, <it>A. fourcroydes</it> and <it>A. angustifolia</it> clones displayed differential expression of the <it>KNOX1</it> gene during <it>in vitro</it> conditions, which is epigenetically regulated by the H3K4me3 and H3K9me2 marks. The finding of an epigenetic regulation in key developmental genes will make it important in future studies to identify factors that help to find climate-resistant micropropagated plants<it>.</it></p

High Temperature and Elevated CO2 Modify Phenology and Growth in Pepper Plants

The aim of this study was to determine the effect of temperature and CO2 on seed emergence, seedling quality, and phenological stage of Capsicum chinense and Capsicum annum cultivated in four controlled growth chambers (C1: 30 &deg;C and 400 &mu;mol CO2 mol&minus;1; C2: 40 &deg;C and 1200 &mu;mol CO2 mol&minus;1; C3: 30 &deg;C and 1200 &mu;mol CO2 mol&minus;1; C4: 40 &deg;C and 400 &mu;mol CO2 mol&minus;1). Neither temperature nor elevated CO2 influenced seed emergence, although differences were observed in seedling mortality, with high temperature affecting seedling survival in both species; the mortality rate at 40 &deg;C was 20 and 53% in C. annuum and 45 and 58% in C. chinense at 400 and 1200 &mu;mol CO2 mol&minus;1, respectively. Differences were also observed in growth parameters, where positive effects were observed on leaf area, which reached 45.9 cm2 in C. annuum and 23.9 cm2 in C. chinense with elevated CO2 at 30 &deg;C, but negative effects were observed with high temperature. CO2 enrichment increased flower and fruit production per plant. However, high temperature delayed flower phenology, increased flower abortion and inhibited fruit set. Elevated CO2 counteracted the detrimental effects of high temperature on growth parameters and flower number, but this was not sufficient to prevent flower abortion and the detrimental morphological characteristics of fruit caused by a temperature of 40 &deg;C

Somatic Embryogenesis: Identified Factors that Lead to Embryogenic Repression. A Case of Species of the Same Genus

<div><p>Somatic embryogenesis is a powerful biotechnological tool for the mass production of economically important cultivars. Due to the cellular totipotency of plants, somatic cells under appropriate conditions are able to develop a complete functional embryo. During the induction of somatic embryogenesis, there are different factors involved in the success or failure of the somatic embryogenesis response. Among these factors, the origin of the explant, the culture medium and the <i>in vitro</i> environmental conditions have been the most studied. However, the secretion of molecules into the media has not been fully addressed. We found that the somatic embryogenesis of <i>Coffea canephora</i>, a highly direct embryogenic species, is disrupted by the metabolites secreted from <i>C</i>. <i>arabica</i>, a poorly direct embryogenic species. These metabolites also affect DNA methylation. Our results show that the abundance of two major phenolic compounds, caffeine and chlorogenic acid, are responsible for inhibiting somatic embryogenesis in <i>C</i>. <i>canephora</i>.</p></div