Vascular Tissue Development and Regeneration in the Model Plant Arabidopsis

Development of vascular tissue is a remarkable example of intercellular communication and coordinated development involving hormonal signaling and tissue polarity. Thus far, studies on vascular patterning and regeneration have been conducted mainly in trees—woody plants—with a well-developed layer of vascular cambium and secondary tissues. Trees are difficult to use as genetic models, i.e., due to long generation time, unstable environmental conditions, and lack of available mutants and transgenic lines. Therefore, the use of the main genetic model plant Arabidopsis thaliana (L.) Heynh., with a wealth of available marker and transgenic lines, provides a unique opportunity to address molecular mechanism of vascular tissue formation and regeneration. With specific treatments, the tiny weed Arabidopsis can serve as a model to understand the growth of mighty trees and interconnect a tree physiology with molecular genetics and cell biology of Arabidopsis

Chapter Vascular Tissue Development and Regeneration in the Model Plant Arabidopsis

Development of vascular tissue is a remarkable example of intercellular communication and coordinated development involving hormonal signaling and tissue polarity. Thus far, studies on vascular patterning and regeneration have been conducted mainly in trees—woody plants—with a well-developed layer of vascular cambium and secondary tissues. Trees are difficult to use as genetic models, i.e., due to long generation time, unstable environmental conditions, and lack of available mutants and transgenic lines. Therefore, the use of the main genetic model plant Arabidopsis thaliana (L.) Heynh., with a wealth of available marker and transgenic lines, provides a unique opportunity to address molecular mechanism of vascular tissue formation and regeneration. With specific treatments, the tiny weed Arabidopsis can serve as a model to understand the growth of mighty trees and interconnect a tree physiology with molecular genetics and cell biology of Arabidopsis

Targeted cell ablation-based insights into wound healing and restorative patterning

Plants as sessile organisms are constantly under attack by herbivores, rough environmental situations, or mechanical pressure. These challenges often lead to the induction of wounds or destruction of already specified and developed tissues. Additionally, wounding makes plants vulnerable to invasion by pathogens, which is why wound signalling often triggers specific defence responses. To stay competitive or, eventually, survive under these circumstances, plants need to regenerate efficiently, which in rigid, tissue migration-incompatible plant tissues requires post-embryonic patterning and organogenesis. Now, several studies used laser-assisted single cell ablation in the Arabidopsis root tip as a minimal wounding proxy. Here, we discuss their findings and put them into context of a broader spectrum of wound signalling, pathogen responses and tissue as well as organ regeneration

Suffix Trees

Sufixový strom je velice zajímavá struktura co se týče práce s řetězci a umožňuje efektivně vykonávat řadu operací nad nimi, např. vyhledávání. Cílem této práce je využití této vlastnosti v kompresním algoritmu, jenž je navržen a implementován. V práci je rozebráno chování sufixového stromu během konstrukce a při simulaci sufixových spojek a, jelikož nezbytnou součástí komprese je udržování textu v posuvném okně, také při posouvání okna. Je navržen a implementován způsob, jak uchovávat pohyby aktivního bodu ve stromu tak, aby bylo možné při dekompresi rekonstruovat původní řetězec. V závěru práce je experimentálně zjištěno a zhodnoceno, jaký vliv na výsledky má komprese nad znaky a nad celými slovy.Suffix tree is very interesting data structure regarding working with strings and enables effective execution of many operations with them, e.g. searching. Aim of this thesis is to use this feature in compression algorithm which is devised and implemented. We analyse behavior of suffix tree during construction and also during suffix links simulation and, because necessary part of compression is keeping of string in sliding window, also during sliding of the window. A way, how to store movement of active point through tree to be able to reconstruct original string at decompression, is devised and implemented. At the end we find out from experiments, what is the difference between results of compression on characters level and on word level.460 - Katedra informatikydobř

Transport Optimisation Module for Traffic Monitoring System

Import 22/07/2015Cílem této práce bylo vytvoření modulu optimalizace přeprav, jehož součástí je rozhraní pro práci s algoritmy knihovny Jsprit a pro zadání vstupů do těchto algoritmů z prostředí frameworku .NET a také práce s mapou OpenLayers -- vykreslování bodů a tras do mapy. Knihovnu Jsprit jsem pomocí nástroje IKVM zpracoval tak, aby ji bylo možné použít z prostředí .NET, což se povedlo.The aim of this thesis was to create transport optimisation module, that consists of interface for working with algorithms from the Jsprit library and for inputing values into these algorithms from .NET framework and also of working with OpenLayers map -- drawing points and strokes to the map. I treated the Jsprit library by IKVM tool in order to be able to use it from the .NET environment and I was successful.460 - Katedra informatikydobř

PIN2 polarity establishment in arabidopsis in the absence of an intact cytoskeleton

Cell polarity is crucial for the coordinated development of all multicellular organisms. In plants, this is exemplified by the PIN-FORMED (PIN) efflux carriers of the phytohormone auxin: The polar subcellular localization of the PINs is instructive to the directional intercellular auxin transport, and thus to a plethora of auxin-regulated growth and developmental processes. Despite its importance, the regulation of PIN polar subcellular localization remains poorly understood. Here, we have employed advanced live-cell imaging techniques to study the roles of microtubules and actin microfilaments in the establishment of apical polar localization of PIN2 in the epidermis of the Arabidopsis root meristem. We report that apical PIN2 polarity requires neither intact actin microfilaments nor microtubules, suggesting that the primary spatial cue for polar PIN distribution is likely independent of cytoskeleton-guided endomembrane trafficking

Pho-view of auxin: Reversible protein phosphorylation in auxin biosynthesis, transport and signaling

The phytohormone auxin plays a central role in shaping plant growth and development. With decades of genetic and biochemical studies, numerous core molecular components and their networks, underlying auxin biosynthesis, transport, and signaling, have been identified. Notably, protein phosphorylation, catalyzed by kinases and oppositely hydrolyzed by phosphatases, has been emerging to be a crucial type of post-translational modification, regulating physiological and developmental auxin output at all levels. In this review, we comprehensively discuss earlier and recent advances in our understanding of genetics, biochemistry, and cell biology of the kinases and phosphatases participating in auxin action. We provide insights into the mechanisms by which reversible protein phosphorylation defines developmental auxin responses, discuss current challenges, and provide our perspectives on future directions involving the integration of the control of protein phosphorylation into the molecular auxin network

Auxin canalization: From speculative models toward molecular players

Among the most fascinated properties of the plant hormone auxin is its ability to promote formation of its own directional transport routes. These gradually narrowing auxin channels form from the auxin source toward the sink and involve coordinated, collective polarization of individual cells. Once established, the channels provide positional information, along which new vascular strands form, for example, during organogenesis, regeneration, or leave venation. The main prerequisite of this still mysterious auxin canalization mechanism is a feedback between auxin signaling and its directional transport. This is manifested by auxin-induced re-arrangements of polar, subcellular localization of PIN-FORMED (PIN) auxin exporters. Immanent open questions relate to how position of auxin source and sink as well as tissue context are sensed and translated into tissue polarization and how cells communicate to polarize coordinately. Recently, identification of the first molecular players opens new avenues into molecular studies of this intriguing example of self-organizing plant development

Reorientation of cortical microtubule arrays in the hypocotyl of arabidopsis thaliana is induced by the cell growth process and independent of auxin signaling

Cortical microtubule arrays in elongating epidermal cells in both the root and stem of plants have the propensity of dynamic reorientations that are correlated with the activation or inhibition of growth. Factors regulating plant growth, among them the hormone auxin, have been recognized as regulators of microtubule array orientations. Some previous work in the field has aimed at elucidating the causal relationship between cell growth, the signaling of auxin or other growth-regulating factors, and microtubule array reorientations, with various conclusions. Here, we revisit this problem of causality with a comprehensive set of experiments in Arabidopsis thaliana, using the now available pharmacological and genetic tools. We use isolated, auxin-depleted hypocotyls, an experimental system allowing for full control of both growth and auxin signaling. We demonstrate that reorientation of microtubules is not directly triggered by an auxin signal during growth activation. Instead, reorientation is triggered by the activation of the growth process itself and is auxin-independent in its nature. We discuss these findings in the context of previous relevant work, including that on the mechanical regulation of microtubule array orientation