whole-mount-clearing-staining-arabidopsis-flower-organs

Whole-mount Clearing and Staining of <em>Arabidopsis</em> Flower Organs and Siliques

Due to its formidable tools for molecular genetic studies, Arabidopsis thaliana is one of the most prominent model species in plant biology and, ...

University of Zurich

In Arabidopsis thaliana, the three MADS box genes SEEDSTICK (STK), SHATTERPROOF1 (SHP1), and SHP2 redundantly regulate ovule development. Protein interaction studies have shown that a multimeric complex composed of the ovule identity proteins together with the SEPALLATA MADS domain proteins is necessary to determine ovule identity. Despite the extensive knowledge that has become available about these MADS domain transcription factors, little is known regarding the genes that they regulate. Here, we show that STK, SHP1, and SHP2 redundantly regulate VERDANDI (VDD), a putative transcription factor that belongs to the plant-specific B3 superfamily. The vdd mutant shows defects during the fertilization process resulting in semisterility. Analysis of the vdd mutant female gametophytes indicates that antipodal and synergid cell identity and/or differentiation are affected. Our results provide insights into the pathways regulated by the ovule identity factors and the role of the downstream target gene VDD in female gametophyte development.

VERDANDI is a direct target of the MADS domain ovule identity complex and affects embryo sac differentiation in Arabidopsis.

Chez Arabidopsis thaliana, le MADS trois box g&egrave;nes SEEDSTICK (STK), SHATTERPROOF1 (SHP1), et SHP2 r&eacute;glementer redondante de d&eacute;veloppement de l&#39;ovule. &Eacute;tudes sur les interactions prot&eacute;iques ont montr&eacute; qu&#39;un complexe de multim&egrave;res compos&eacute; des prot&eacute;ines ainsi que les prot&eacute;ines de domaine MADS SEPALLATA identit&eacute; ovule est n&eacute;cessaire pour d&eacute;terminer l&#39;identit&eacute; de l&#39;ovule. Malgr&eacute; les connaissances approfondies qui sont apparues sur ces facteurs de transcription de domaine MADS, peu est connu au sujet des g&egrave;nes qu&#39;ils r&eacute;gulent. Ici, nous montrons que STK, SHP1 et SHP2 redondante r&eacute;glementent VERDANDI (DMV), un facteur de transcription putatif qui appartient &agrave; la superfamille des B3-sp&eacute;cifiques &agrave; l&#39;installation. Le mutant de la DMV montre des d&eacute;fauts au cours du processus de f&eacute;condation d&#39;o&ugrave; semisterility. Analyse des gam&eacute;tophytes femelles mutantes DMV indique que diam&eacute;tralement oppos&eacute;es et synergides cellule identit&eacute; et/ou de diff&eacute;renciation est touch&eacute;e. Nos r&eacute;sultats donnent un aper&ccedil;u dans les voies r&eacute;gies par des facteurs d&#39;identit&eacute; de l&#39;ovule et le r&ocirc;le du g&egrave;ne cible en aval la DMV dans le d&eacute;veloppement du gam&eacute;tophyte femelle.

VERDANDI est la cible directe de l&#39;identit&eacute; de l&#39;ovule de domaine MADS complexe et affecte la diff&eacute;renciation du sac embryonnaire chez Arabidopsis.

In Arabidopsis thaliana, il MADS tre box geni SEEDSTICK (STK), SHATTERPROOF1 (SHP1), e SHP2 ridondante regolare lo sviluppo ovulo. Studi di interazione della proteina hanno dimostrato che un multimerica complessa composta da proteine di identit&agrave; l&#39;ovulo insieme con le proteine del dominio SEPALLATA MADS &egrave; necessaria per determinare l&#39;identit&agrave; di ovulo. Nonostante la vasta conoscenza che &egrave; diventato disponibile su questi fattori di trascrizione di dominio MADS, poco &egrave; noto per quanto riguarda i geni che regolano. Qui, ci mostra che STK, SHP1, SHP2 ridondante regolano VERDANDI (VDD), un fattore di trascrizione putativo che appartiene alla Superfamiglia B3 impianto specifico. Il mutante vdd mostra difetti durante il processo di fecondazione con conseguente semisterility. Analisi della vdd mutante gametophytes femminili indicano che antipodali e synergid cella identit&agrave; e/o differenziazione &egrave; colpiti. I nostri risultati forniscono approfondimenti le vie regolamentate da fattori di identit&agrave; l&#39;ovulo e il ruolo del gene bersaglio a valle VDD nello sviluppo del gametofito femminile.

VERDANDI &egrave; un bersaglio diretto di MADS identit&agrave; del dominio dell&#39;ovulo complesso e colpisce il sacco embrionale differenziazione in Arabidopsis.

Plant cell expansion is controlled by a fine-tuned balance between intracellular turgor pressure, cell wall loosening and cell wall biosynthesis. To understand these processes, it is important to gain in-depth knowledge of cell wall mechanics. Pollen tubes are tip-growing cells that provide an ideal system to study mechanical properties at the single cell level. With the available approaches it was not easy to measure important mechanical parameters of pollen tubes, such as the elasticity of the cell wall. We used a cellular force microscope (CFM) to measure the apparent stiffness of lily pollen tubes. In combination with a mechanical model based on the finite element method (FEM), this allowed us to calculate turgor pressure and cell wall elasticity, which we found to be around 0.3 MPa and 20-90 MPa, respectively. Furthermore, and in contrast to previous reports, we showed that the difference in stiffness between the pollen tube tip and the shank can be explained solely by the geometry of the pollen tube. CFM, in combination with an FEM-based model, provides a powerful method to evaluate important mechanical parameters of single, growing cells. Our findings indicate that the cell wall of growing pollen tubes has mechanical properties similar to rubber. This suggests that a fully turgid pollen tube is a relatively stiff, yet flexible cell that can react very quickly to obstacles or attractants by adjusting the direction of growth on its way through the female transmitting tissue.

The pollen tube: a soft shell with a hard core.

Expansion des cellules v&eacute;g&eacute;tales est contr&ocirc;l&eacute;e par un &eacute;quilibre finement &eacute;labor&eacute; entre la pression osmotique intracellulaire, le rel&acirc;chement de la paroi cellulaire et la biosynth&egrave;se de la paroi cellulaire. Pour comprendre ces processus, il est important d&#39;acqu&eacute;rir une connaissance approfondie de la m&eacute;canique de la paroi cellulaire. Les tubes polliniques sont productrices de pointe cellules qui fournissent un syst&egrave;me id&eacute;al pour &eacute;tudier les propri&eacute;t&eacute;s m&eacute;caniques au niveau de la cellule unique. Avec les approches disponibles, il n&#39;&eacute;tait pas facile de mesurer des param&egrave;tres m&eacute;caniques importants des tubes polliniques, tels que l&#39;&eacute;lasticit&eacute; de la paroi cellulaire. Nous avons utilis&eacute; un microscope &agrave; force cellulaire (CFM) pour mesurer la rigidit&eacute; apparente des tubes polliniques de lily. En combinaison avec un mod&egrave;le m&eacute;canique bas&eacute; sur la m&eacute;thode des &eacute;l&eacute;ments finis (MEF), cela nous a permis de calculer la pression de turgescence et &eacute;lasticit&eacute; de la paroi de la cellule, que nous avons trouv&eacute; &agrave; environ 0,3 MPa et 20-90 MPa, respectivement. En outre et contrairement aux rapports pr&eacute;c&eacute;dents, nous avons montr&eacute; que la diff&eacute;rence de rigidit&eacute; entre l&#39;extr&eacute;mit&eacute; du tube pollinique et la tige peut s&#39;expliquer uniquement par la g&eacute;om&eacute;trie du tube pollinique. CFM, en combinaison avec un mod&egrave;le MEF, fournit une m&eacute;thode puissante pour &eacute;valuer les param&egrave;tres m&eacute;caniques importants d&#39;unique, les cellules en croissance. Nos r&eacute;sultats indiquent que la paroi cellulaire des tubes polliniques de plus en plus a des propri&eacute;t&eacute;s m&eacute;caniques similaires au caoutchouc. Ceci sugg&egrave;re qu&#39;un tube pollinique enti&egrave;rement turgescents est une cellule relativement raide, mais souple qui peut r&eacute;agir tr&egrave;s rapidement &agrave; des obstacles ou des substances attractives en ajustant la direction de la croissance sur son chemin &agrave; travers la femelle transmettant des tissus.

Le tube pollinique : une carapace molle avec un noyau dur.

Espansione delle cellule vegetali &egrave; controllato da un perfetto equilibrio tra turgescenza intracellulare, allentamento della parete cellulare e la parete delle cellule biosintesi. Per capire questi processi, &egrave; importante acquisire una conoscenza approfondita della meccanica della parete cellulare. Tubi pollinici sono punta-crescita delle cellule che forniscono un sistema ideale per studiare le propriet&agrave; meccaniche a livello di singola cellula. Con gli approcci disponibili non &egrave; stato facile misurare importanti parametri meccanici di tubi pollinici, ad esempio l&#39;elasticit&agrave; della parete delle cellule. Abbiamo utilizzato un microscopio a forza cellulare (CFM) per misurare l&#39;apparente rigidit&agrave; dei tubi pollinici giglio. In combinazione con un modello meccanico basato sul metodo degli elementi finiti (FEM), questo ci ha permesso di calcolare il turgore e l&#39;elasticit&agrave; della parete delle cellule, che abbiamo trovato a circa 0,3 MPa e 20-90 MPa, rispettivamente. Inoltre e contrariamente a precedenti relazioni, abbiamo dimostrato che la differenza di rigidezza tra la punta del tubo pollinico e la tibia pu&ograve; essere spiegata unicamente dalla geometria del tubo di polline. CFM, in combinazione con un modello basato su FEM, fornisce un metodo potente per valutare importanti parametri meccanici del singolo, le cellule in crescita. I nostri risultati indicano che la parete cellulare dei tubi pollinici in crescita ha propriet&agrave; meccaniche simili alla gomma. Questo suggerisce che un tubo pollinico completamente turgido &egrave; una cella relativamente rigida, ma flessibile che pu&ograve; reagire molto rapidamente a ostacoli o attrattivi regolando la direzione della crescita nel suo cammino attraverso la femmina trasmissione di tessuto.

Il tubo pollinico: un guscio morbido con un nocciolo duro.

Over 70 years ago, increased spontaneous mutation rates were observed in Drosophila spp. hybrids, but the genetic basis of this phenomenon is not well understood. The model plant Arabidopsis (Arabidopsis thaliana) offers unique opportunities to study the types of mutations induced upon hybridization and the frequency of their occurrence. Understanding the mutational effects of hybridization is important, as many crop plants are grown as hybrids. Besides, hybridization is important for speciation and its effects on genome integrity could be critical, as chromosomal rearrangements can lead to reproductive isolation. We examined the rates of hybridization-induced point and frameshift mutations as well as homologous recombination events in intraspecific Arabidopsis hybrids using a set of transgenic mutation detector lines that carry mutated or truncated versions of a reporter gene. We found that hybridization alters the frequency of different kinds of mutations. In general, Columbia (Col)×Cape Verde Islands and Col×C24 hybrid progeny had decreased T→G and T→A transversion rates but an increased C→T transition rate. Significant changes in frameshift mutation rates were also observed in some hybrids. In Col×C24 hybrids, there is a trend for increased homologous recombination rates, except for the hybrids from one line, while in Col×Cape Verde Islands hybrids, this rate is decreased. The overall genetic distance of the parents had no influence on mutation rates in the progeny, as closely related accessions on occasion displayed higher mutation rates than accessions that are separated farther apart. However, reciprocal hybrids had significantly different mutation rates, suggesting parent-of-origin-dependent effects on the mutation frequency.

Hybridization alters spontaneous mutation rates in a parent-of-origin-dependent fashion in Arabidopsis.

The pollen tube (PT) serves as a model system for investigating plant cell growth and morphogenesis. Ultrastructural studies are indispensable to complement data from physiological and genetic analyses, yet an effective method is lacking for PTs of the model plant Arabidopsis thaliana.

Article	Year
VERDANDI is a direct target of the MADS domain ovule identity complex and affects embryo sac differentiation in Arabidopsis. The Plant cell\| PubMed ID: 20581305	2010
The pollen tube: a soft shell with a hard core. The Plant journal : for cell and molecular biology\| PubMed ID: 23106269	2013
Hybridization alters spontaneous mutation rates in a parent-of-origin-dependent fashion in Arabidopsis. Plant physiology\| PubMed ID: 24664208	2014
Efficient preparation of Arabidopsis pollen tubes for ultrastructural analysis using chemical and cryo-fixation. BMC plant biology\| PubMed ID: 29078752	2017

Christof Eichenberger

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