Integrative Proteomics and Metabolomics Analysis Reveals the Role of Small Signaling Peptide Rapid Alkalinization Factor 34 (RALF34) in Cucumber Roots

The main role of RALF small signaling peptides was reported to be the alkalization control of the apoplast for improvement of nutrient absorption; however, the exact function of individual RALF peptides such as RALF34 remains unknown. The Arabidopsis RALF34 (AtRALF34) peptide was proposed to be part of the gene regulatory network of lateral root initiation. Cucumber is an excellent model for studying a special form of lateral root initiation taking place in the meristem of the parental root. We attempted to elucidate the role of the regulatory pathway in which RALF34 is a participant using cucumber transgenic hairy roots overexpressing CsRALF34 for comprehensive, integrated metabolomics and proteomics studies, focusing on the analysis of stress response markers. CsRALF34 overexpression resulted in the inhibition of root growth and regulation of cell proliferation, specifically in blocking the G2/M transition in cucumber roots. Based on these results, we propose that CsRALF34 is not part of the gene regulatory networks involved in the early steps of lateral root initiation. Instead, we suggest that CsRALF34 modulates ROS homeostasis and triggers the controlled production of hydroxyl radicals in root cells, possibly associated with intracellular signal transduction. Altogether, our results support the role of RALF peptides as ROS regulators.

Lateral Root Initiation in the Parental Root Meristem of Cucurbits: Old Players in a New Position

While in most higher plants, including the model system Arabidopsis thaliana, the formation of lateral root primordia is induced in the elongation zone of the parental root, in seven plant families, including Cucurbitaceae, an alternative root branching mechanism is established such that lateral roots are initiated directly in the apical meristem of the parental root. In Arabidopsis, the transcription factor GATA23 and MEMBRANE-ASSOCIATED KINASE REGULATOR4 (MAKR4) are involved in the gene regulatory network of lateral root initiation. Among all marker genes examined, these are the earliest known marker genes up-regulated by auxin during lateral root initiation. In this study, putative functional orthologs of Arabidopsis GATA23 and MAKR4 were identified in cucumber (Cucumis sativus) and squash (Cucurbita pepo). Both cucurbits contained 26 genes encoding GATA family transcription factors and only one MAKR4 gene. Phylogenetic and transcriptional analysis of up-regulation by auxin led to the identification of GATA23 putative functional orthologs in Cucurbitaceae - CpGATA24 and CsGATA24. In squash, CpMAKR4 was up-regulated by naphthylacetic acid (NAA) and, similar to MAKR4 in Arabidopsis, indole-3-butyric acid (IBA). A detailed analysis of the expression pattern of CpGATA24 and CpMAKR4 in squash roots from founder cell specification until emergence of lateral root primordia was carried out using promoter-fluorescent reporter gene fusions and confocal microscopy. Their expression was induced in the protoxylem, and then expanded to founder cells in the pericycle. Thus, while the overall expression pattern of these genes was significantly different from that in Arabidopsis, in founder cells their expression was induced in the same order as in Arabidopsis. Altogether, these findings suggest that in Cucurbitaceae the putative functional orthologs of GATA23 and MAKR4 might play a role in founder cell specification and primordium positioning during lateral root initiation. The role of the protoxylem in auxin transport as a trigger of founder cells specification and lateral root initiation is discussed.

[Pathomorphological and morphometric evaluation of a model of aortic insufficiency in rabbits treated with taurine]

In 45 experimental rabbits, subjected to trans-carotid aorto-valvulotomy in a month developed a congestive heart failure. When this group of rabbits was compared to the control group of 20 animals, in the course of complete pathomorphologic, histochemical and stereomorphologic analysis the following results were obtained: potassium oroticum did not show any efficacy at all; the efficacy of taurine in a dose of 10 mg/kg was low. Its effect was both direct and indirect acting through the autonomic nervous system.

[Effect of fenicoberan on parameters of carbohydrate metabolism and electrolyte levels in blood vessel tissue]

The spasmolysant fenicaberane was found to induce diverse changes in electrolyte levels, a significant increase of lactate content in all vascular zones, various changes in pyruvate levels depending on the vascular tissue type.

[Pathomorphological criteria of anti-atherosclerotic effect of plant saponins in an experiment]

6-month hypercholesterol diet made it possible to obtain an adequate model of atherosclerosis in inbred rats. The model was characterized by lipoidosis and fibrous plaques which occupied half of the area of the aorta and coronary arteries, as well as secondary fibrosis of other organs. During atherogenesis changes in endothelial and myocyte cells appear, accumulation of acid glycosaminoglycans takes place, lipoidosis and elastofibrosis progress up to collagenization and hyalinosis of the arterial wall. Fibro-myocyte plaques are transformed into fibro-atheromatous plaques. Upon drug therapy with vegetative saponins and furastonolic glycosides fibrous lesions did not regress, but delipidization and translocation of glycosaminoglycans were observed in 30% of the area of the affected arteries, and elastofibrosis and changes in endothelial and myocyte cells were decreased. Long-term therapy with vegetative drugs produced a regression of the experimental atherosclerosis.