Galacturonosyltransferase 4 silencing alters pectin composition and carbon partitioning in tomato

Pectin is a main component of the plant cell wall and is the most complex family of polysaccharides in nature. Its composition is essential for the normal growth and morphology pattern, as demonstrated by pectin-defective mutant phenotypes. Besides this basic role in plant physiology, in tomato, pectin structure contributes to very important quality traits such as fruit firmness. Sixty-seven different enzymatic activities have been suggested to be required for pectin biosynthesis, but only a few genes have been identified and studied so far. This study characterized the tomato galacturonosyltransferase (GAUT) family and performed a detailed functional study of the GAUT4 gene. The tomato genome harbours all genes orthologous to those described previously in Arabidopsis thaliana, and a transcriptional profile revealed that the GAUT4 gene was expressed at higher levels in developing organs. GAUT4-silenced tomato plants exhibited an increment in vegetative biomass associated with palisade parenchyma enlargement. Silenced fruits showed an altered pectin composition and accumulated less starch along with a reduced amount of pectin, which coincided with an increase in firmness. Moreover, the harvest index was dramatically reduced as a consequence of the reduction in the fruit weight and number. Altogether, these results suggest that, beyond its role in pectin biosynthesis, GAUT4 interferes with carbon metabolism, partitioning, and allocation. Hence, this cell-wall-related gene seems to be key in determining plant growth and fruit production in tomato

Anticancer prodrugs of butyric acid and formaldehyde protect against doxorubicin-induced cardiotoxicity

Formaldehyde has been previously shown to play a dominant role in promoting synergy between doxorubicin (Dox) and formaldehyde-releasing butyric acid (BA) prodrugs in killing cancer cells. In this work, we report that these prodrugs also protect neonatal rat cardiomyocytes and adult mice against toxicity elicited by Dox. In cardiomyocytes treated with Dox, the formaldehyde releasing prodrugs butyroyloxymethyl diethylphosphate (AN-7) and butyroyloxymethyl butyrate (AN-1), but not the corresponding acetaldehyde-releasing butyroyloxydiethyl phosphate (AN-88) or butyroyloxyethyl butyrate (AN-11), reduced lactate dehydrogenase leakage, prevented loss of mitochondrial membrane potential (ΔΨm) and attenuated upregulation of the proapoptotic gene Bax. In Dox-treated mice, AN-7 but not AN-88 attenuated weight-loss and mortality, and increase in serum lactate dehydrogenase. These findings show that BA prodrugs that release formaldehyde and augment Dox anticancer activity also protect against Dox cardiotoxicity. Based on these observations, clinical applications of these prodrugs for patients treated with Dox warrant further investigation

Co-variation network based on gene expression and non-structural carbohydrate (NSC) content.

<p>Red circles and blue boxes represent gene and metabolite nodes, respectively. Continuous and dashed lines represent positive and negative correlations, respectively. The network was constructed using the R Stats package [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0180051#pone.0180051.ref054" target="_blank">54</a>] and networks were built and drawn using the R Igraph package [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0180051#pone.0180051.ref057" target="_blank">57</a>].</p

Carbohydrate-mediated responses during zygotic and early somatic embryogenesis in the endangered conifer, <i>Araucaria angustifolia</i>

<div><p>Three zygotic developmental stages and two somatic <i>Araucaria angustifolia</i> cell lines with contrasting embryogenic potential were analyzed to identify the carbohydrate-mediated responses associated with embryo formation. Using a comparison between zygotic and somatic embryogenesis systems, the non-structural carbohydrate content, cell wall sugar composition and expression of genes involved in sugar sensing were analyzed, and a network analysis was used to identify coordinated features during embryogenesis. We observed that carbohydrate-mediated responses occur mainly during the early stages of zygotic embryo formation, and that during seed development there are coordinated changes that affect the development of the different structures (embryo and megagametophyte). Furthermore, sucrose and starch accumulation were associated with the responsiveness of the cell lines. This study sheds light on how carbohydrate metabolism is influenced during zygotic and somatic embryogenesis in the endangered conifer species, <i>A</i>. <i>angustifolia</i>.</p></div

<i>Araucaria angustifolia</i> zygotic and somatic samples used in this study.

<p>Globular zygotic embryo with megagametophyte (GZE) (a); cotyledonal zygotic embryo (CZE) (b) and the corresponding megagametophyte (CZEMG) (c); mature zygotic embryo (MZE) (d) and the corresponding megagametophyte (MZEMG) (e); abscisic acid (ABA)-responsive (SE1) (f) and ABA-blocked (SE6) (g) cell lines in proliferation medium, and the development of proembryogenic masses (PEMs) (h, i and j); mature ABA-responsive (S1M) (k) and mature ABA-blocked (S6M) (l) embryogenic cell lines. Arrow indicates globular somatic embryo. Scale bars: a-g, l = 5 mm; h-j = 0.2 mm = 10 mm.</p