Aurora kinases are key regulators of mitosis. Multicellular eukaryotes generally possess two functionally diverged types of Aurora kinases. In plants, including Arabidopsis (Arabidopsis thaliana), these are termed α- and β-Auroras. As the functional specification of Aurora kinases is determined by their specific interaction partners, we initiated interactomics analyses using both Arabidopsis α-Aurora kinases (AUR1 and AUR2). Proteomics results revealed that TPX2-LIKE PROTEINS2 and 3 (TPXL2/3) prominently associated with α-Auroras, as did the conserved TPX2 to a lower degree. Like TPX2, TPXL2 and TPXL3 strongly activated the AUR1 kinase but exhibited cell-cycle-dependent localization differences on microtubule arrays. The separate functions of TPX2 and TPXL2/3 were also suggested by their different influences on AUR1 localization upon ectopic expressions. Furthermore, genetic analyses showed that TPXL3, but not TPX2 and TPXL2, acts nonredundantly to enable proper embryo development. In contrast to vertebrates, plants have an expanded TPX2 family and these family members have both redundant and unique functions. Moreover, as neither TPXL2 nor TPXL3 contains the C-terminal Kinesin-5 binding domain present in the canonical TPX2, the targeting and activity of this kinesin must be organized differently in plants.

• MeSH
• aktivace enzymů genetika   MeSH
• Arabidopsis embryologie   genetika   metabolismus   MeSH
• geneticky modifikované rostliny MeSH
• konfokální mikroskopie MeSH
• protein-serin-threoninkinasy genetika   metabolismus   MeSH
• proteiny asociované s mikrotubuly genetika   metabolismus   MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• proteomika metody   MeSH
• regulace genové exprese u rostlin MeSH
• sekvence aminokyselin MeSH
• sekvenční homologie aminokyselin MeSH
• semena rostlinná embryologie   genetika   metabolismus   MeSH
• vazba proteinů MeSH
• vývojová regulace genové exprese MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

The maintenance of genome integrity over cell divisions is critical for plant development and the correct transmission of genetic information to the progeny. A key factor involved in this process is the STRUCTURAL MAINTENANCE OF CHROMOSOME5 (SMC5) and SMC6 (SMC5/6) complex, related to the cohesin and condensin complexes that control sister chromatid alignment and chromosome condensation, respectively. Here, we characterize NON-SMC ELEMENT4 (NSE4) paralogs of the SMC5/6 complex in Arabidopsis (Arabidopsis thaliana). NSE4A is expressed in meristems and accumulates during DNA damage repair. Partial loss-of-function nse4a mutants are viable but hypersensitive to DNA damage induced by zebularine. In addition, nse4a mutants produce abnormal seeds, with noncellularized endosperm and embryos that maximally develop to the heart or torpedo stage. This phenotype resembles the defects in cohesin and condensin mutants and suggests a role for all three SMC complexes in differentiation during seed development. By contrast, NSE4B is expressed in only a few cell types, and loss-of-function mutants do not have any obvious abnormal phenotype. In summary, our study shows that the NSE4A subunit of the SMC5-SMC6 complex is essential for DNA damage repair in somatic tissues and plays a role in plant reproduction.

• MeSH
• Arabidopsis embryologie   genetika   imunologie   MeSH
• duplikace genu MeSH
• genom rostlinný MeSH
• oprava DNA * genetika   MeSH
• podjednotky proteinů metabolismus   MeSH
• poškození DNA * genetika   MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• pyl genetika   MeSH
• regulace genové exprese u rostlin MeSH
• semena rostlinná genetika   metabolismus   MeSH
• transkriptom genetika   MeSH
• upregulace genetika   MeSH
• vajíčko rostlin genetika   MeSH
• vazba proteinů MeSH
• vývojová regulace genové exprese MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Mutual interactions of the phytohormones, cytokinins and auxin determine root or shoot identity during postembryonic de novo organogenesis in plants. However, our understanding of the role of hormonal metabolism and perception during early stages of cell fate reprogramming is still elusive. Here we show that auxin activates root formation, whereas cytokinins mediate early loss of the root identity, primordia disorganisation and initiation of shoot development. Exogenous and endogenous cytokinins influence the initiation of newly formed organs, as well as the pace of organ development. The process of de novo shoot apical meristem establishment is accompanied by accumulation of endogenous cytokinins, differential regulation of genes for individual cytokinin receptors, strong activation of AHK4-mediated signalling and induction of the shoot-specific homeodomain regulator WUSCHEL. The last is associated with upregulation of isopentenyladenine-type cytokinins, revealing higher shoot-forming potential when compared with trans-zeatin. Moreover, AHK4-controlled cytokinin signalling negatively regulates the root stem cell organiser WUSCHEL RELATED HOMEOBOX 5 in the root quiescent centre. We propose an important role for endogenous cytokinin biosynthesis and AHK4-mediated cytokinin signalling in the control of de novo-induced organ identity.

• MeSH
• Arabidopsis cytologie   embryologie   genetika   MeSH
• cytokininy genetika   metabolismus   MeSH
• homeodoménové proteiny genetika   metabolismus   MeSH
• meristém cytologie   embryologie   MeSH
• organogeneze rostlin fyziologie   MeSH
• proteinkinasy genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• receptory buněčného povrchu genetika   metabolismus   MeSH
• signální transdukce fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The Arabidopsis (Arabidopsis thaliana) gynoecium consists of two congenitally fused carpels made up of two lateral valve domains and two medial domains, which retain meristematic properties and later fuse to produce the female reproductive structures vital for fertilization. Polar auxin transport (PAT) is important for setting up distinct apical auxin signaling domains in the early floral meristem remnants allowing for lateral domain identity and outgrowth. Crosstalk between auxin and cytokinin plays an important role in the development of other meristematic tissues, but hormone interaction studies to date have focused on more accessible later-stage gynoecia and the spatiotemporal interactions pivotal for patterning of early gynoecium primordia remain unknown. Focusing on the earliest stages, we propose a cytokinin-auxin feedback model during early gynoecium patterning and hormone homeostasis. Our results suggest that cytokinin positively regulates auxin signaling in the incipient gynoecial primordium and strengthen the concept that cytokinin regulates auxin homeostasis during gynoecium development. Specifically, medial cytokinin promotes auxin biosynthesis components [YUCCA1/4 (YUC1/4)] in, and PINFORMED7 (PIN7)-mediated auxin efflux from, the medial domain. The resulting laterally focused auxin signaling triggers ARABIDOPSIS HISTIDINE PHOSPHOTRANSFER PROTEIN6 (AHP6), which then represses cytokinin signaling in a PAT-dependent feedback. Cytokinin also down-regulates PIN3, promoting auxin accumulation in the apex. The yuc1, yuc4, and ahp6 mutants are hypersensitive to exogenous cytokinin and 1-napthylphthalamic acid (NPA), highlighting their role in mediolateral gynoecium patterning. In summary, these mechanisms self-regulate cytokinin and auxin signaling domains, ensuring correct domain specification and gynoecium development.

• MeSH
• Arabidopsis embryologie   genetika   metabolismus   MeSH
• biologické modely MeSH
• biologický transport MeSH
• cytokininy metabolismus   MeSH
• homeostáza MeSH
• květy embryologie   MeSH
• kyseliny indoloctové metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• regulátory růstu rostlin metabolismus   MeSH
• rostlinné geny MeSH
• rozvržení tělního plánu * MeSH
• signální transdukce * MeSH
• upregulace MeSH
• Publikační typ
• časopisecké články MeSH

Metal accumulation in seeds is a prerequisite for germination and establishment of plants but also for micronutrient delivery to humans. To investigate metal transport processes and their interactions in seeds, we focused on METAL TOLERANCE PROTEIN8 (MTP8), a tonoplast transporter of the manganese (Mn) subclade of cation diffusion facilitators, which in Arabidopsis (Arabidopsis thaliana) is expressed in embryos of seeds. The x-ray fluorescence imaging showed that expression of MTP8 was responsible for Mn localization in subepidermal cells on the abaxial side of the cotyledons and in cortical cells of the hypocotyl. Accordingly, under low Mn availability, MTP8 increased seed stores of Mn, required for efficient seed germination. In mutant embryos lacking expression ofVACUOLAR IRON TRANSPORTER1(VIT1), MTP8 built up iron (Fe) hotspots inMTP8-expressing cells types, suggesting that MTP8 transports Fe in addition to Mn. Inmtp8 vit1double mutant seeds, Mn and Fe were distributed in all cell types of the embryo. An Fe transport function of MTP8 was confirmed by its ability to complement Fe hypersensitivity of a yeast mutant defective in vacuolar Fe transport. Imbibingmtp8-1mutant seeds in the presence of Mn or subjecting seeds to wet-dry cycles showed that MTP8 conferred Mn tolerance. During germination, MTP8 promoted reallocation of Fe from the vasculature. These results indicate that cell type-specific accumulation of Mn and Fe in seeds depends on MTP8 and that this transporter plays an important role in the generation of seed metal stores as well as for metal homeostasis and germination efficiency under challenging environmental conditions.

• MeSH
• Arabidopsis embryologie   genetika   metabolismus   MeSH
• biologické modely MeSH
• genový knockout MeSH
• homeostáza * MeSH
• klíčení * genetika   MeSH
• mangan metabolismus   MeSH
• mutace genetika   MeSH
• promotorové oblasti (genetika) genetika   MeSH
• proteiny huseníčku metabolismus   MeSH
• proteiny přenášející kationty metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• Saccharomyces cerevisiae metabolismus   MeSH
• semena rostlinná embryologie   genetika   MeSH
• spektrometrie rentgenová emisní MeSH
• testy genetické komplementace MeSH
• vývojová regulace genové exprese MeSH
• železo metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH

The plant hormone auxin and its directional transport are known to play a crucial role in defining the embryonic axis and subsequent development of the body plan. Although the role of PIN auxin efflux transporters has been clearly assigned during embryonic shoot and root specification, the role of the auxin influx carriers AUX1 and LIKE-AUX1 (LAX) proteins is not well established. Here, we used chemical and genetic tools on Brassica napus microspore-derived embryos and Arabidopsis thaliana zygotic embryos, and demonstrate that AUX1, LAX1 and LAX2 are required for both shoot and root pole formation, in concert with PIN efflux carriers. Furthermore, we uncovered a positive-feedback loop between MONOPTEROS (ARF5)-dependent auxin signalling and auxin transport. This MONOPTEROS-dependent transcriptional regulation of auxin influx (AUX1, LAX1 and LAX2) and auxin efflux (PIN1 and PIN4) carriers by MONOPTEROS helps to maintain proper auxin transport to the root tip. These results indicate that auxin-dependent cell specification during embryo development requires balanced auxin transport involving both influx and efflux mechanisms, and that this transport is maintained by a positive transcriptional feedback on auxin signalling.

• MeSH
• Arabidopsis embryologie   genetika   metabolismus   MeSH
• biologický transport genetika   fyziologie   MeSH
• Brassica napus embryologie   genetika   metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• rostlinné proteiny metabolismus   MeSH
• semena rostlinná cytologie   metabolismus   MeSH
• signální transdukce genetika   fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Plant sexual reproduction involves highly structured and specialized organs: stamens (male) and gynoecia (female, containing ovules). These organs synchronously develop within protective flower buds, until anthesis, via tightly coordinated mechanisms that are essential for effective fertilization and production of viable seeds. The phytohormone auxin is one of the key endogenous signalling molecules controlling initiation and development of these, and other, plant organs. In particular, its uneven distribution, resulting from tightly controlled production, metabolism and directional transport, is an important morphogenic factor. In this review we discuss how developmentally controlled and localized auxin biosynthesis and transport contribute to the coordinated development of plants' reproductive organs, and their fertilized derivatives (embryos) via the regulation of auxin levels and distribution within and around them. Current understanding of the links between de novo local auxin biosynthesis, auxin transport and/or signalling is presented to highlight the importance of the non-cell autonomous action of auxin production on development and morphogenesis of reproductive organs and embryos. An overview of transcription factor families, which spatiotemporally define local auxin production by controlling key auxin biosynthetic enzymes, is also presented.

• MeSH
• Arabidopsis embryologie   růst a vývoj   metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• morfogeneze MeSH
• regulátory růstu rostlin metabolismus   MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• transkripční faktory genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

The role of YODA MITOGEN ACTIVATED PROTEIN KINASE KINASE KINASE 4 (MAPKKK4) upstream of MITOGEN ACTIVATED PROTEIN KINASE 6 (MPK6) was studied during post-embryonic root development of Arabidopsis thaliana. Loss- and gain-of-function mutants of YODA (yda1 and ΔNyda1) were characterized in terms of root patterning, endogenous auxin content and global proteomes. We surveyed morphological and cellular phenotypes of yda1 and ΔNyda1 mutants suggesting possible involvement of auxin. Endogenous indole-3-acetic acid (IAA) levels were up-regulated in both mutants. Proteomic analysis revealed up-regulation of auxin biosynthetic enzymes tryptophan synthase and nitrilases in these mutants. The expression, abundance and phosphorylation of MPK3, MPK6 and MICROTUBULE ASSOCIATED PROTEIN 65-1 (MAP65-1) were characterized by quantitative polymerase chain reaction (PCR) and western blot analyses and interactions between MAP65-1, microtubules and MPK6 were resolved by quantitative co-localization studies and co-immunoprecipitations. yda1 and ΔNyda1 mutants showed disoriented cell divisions in primary and lateral roots, abortive cytokinesis, and differential subcellular localization of MPK6 and MAP65-1. They also showed deregulated expression of TANGLED1 (TAN1), PHRAGMOPLAST ORIENTING KINESIN 1 (POK1), and GAMMA TUBULIN COMPLEX PROTEIN 4 (GCP4). The findings that MPK6 localized to preprophase bands (PPBs) and phragmoplasts while the mpk6-4 mutant transformed with MPK6AEF (alanine (A)-glutamic acid (E)-phenylanine (F)) showed a root phenotype similar to that of yda1 demonstrated that MPK6 is an important player downstream of YODA. These data indicate that YODA and MPK6 are involved in post-embryonic root development through an auxin-dependent mechanism regulating cell division and mitotic microtubule (PPB and phragmoplast) organization.

• MeSH
• Arabidopsis cytologie   účinky léků   embryologie   enzymologie   MeSH
• buněčné dělení * účinky léků   MeSH
• cytokineze účinky léků   MeSH
• epidermis rostlin cytologie   MeSH
• fenotyp MeSH
• fluorescenční protilátková technika MeSH
• fosforylace účinky léků   MeSH
• interfáze MeSH
• kořeny rostlin anatomie a histologie   cytologie   embryologie   MeSH
• kyseliny indoloctové metabolismus   farmakologie   MeSH
• MAP kinasy kinas (kinas) metabolismus   MeSH
• meristém cytologie   účinky léků   MeSH
• mikrotubuly účinky léků   metabolismus   MeSH
• mitogenem aktivované proteinkinasy metabolismus   MeSH
• mitóza účinky léků   MeSH
• mutace genetika   MeSH
• proteiny huseníčku metabolismus   MeSH
• proteomika MeSH
• transport proteinů účinky léků   MeSH
• upregulace * účinky léků   MeSH
• vazba proteinů účinky léků   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

In higher plants, cell cycle activation in the meristems at germination is essential for the initiation of post-embryonic development. We previously identified the signaling pathways of homeobox transcription factor STIMPY and metabolic sugars as two interacting branches of the regulatory network that is responsible for activating meristematic tissue proliferation in Arabidopsis. In this study, we found that CYCP2;1 is both a direct target of STIMPY transcriptional activation and an early responder to sugar signals. Genetic and molecular studies show that CYCP2;1 physically interacts with three of the five mitotic CDKs in Arabidopsis, and is required for the G2 to M transition during meristem activation. Taken together, our results suggest that CYCP2;1 acts as a permissive control of cell cycle progression during seedling establishment by directly linking genetic control and nutritional cues with the activity of the core cell cycle machinery.

• MeSH
• aktivace transkripce MeSH
• Arabidopsis embryologie   MeSH
• buněčné dělení genetika   MeSH
• cyklin-dependentní kinasy biosyntéza   MeSH
• cykliny biosyntéza   genetika   metabolismus   MeSH
• homeodoménové proteiny genetika   MeSH
• meristém cytologie   embryologie   MeSH
• proliferace buněk MeSH
• proteiny huseníčku biosyntéza   genetika   metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• rostlinné geny MeSH
• sacharosa farmakologie   MeSH
• semenáček genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

Establishment of the embryonic axis foreshadows the main body axis of adults both in plants and in animals, but underlying mechanisms are considered distinct. Plants utilize directional, cell-to-cell transport of the growth hormone auxin to generate an asymmetric auxin response that specifies the embryonic apical-basal axis. The auxin flow directionality depends on the polarized subcellular localization of PIN-FORMED (PIN) auxin transporters. It remains unknown which mechanisms and spatial cues guide cell polarization and axis orientation in early embryos. Herein, we provide conceptually novel insights into the formation of embryonic axis in Arabidopsis by identifying a crucial role of localized tryptophan-dependent auxin biosynthesis. Local auxin production at the base of young embryos and the accompanying PIN7-mediated auxin flow toward the proembryo are required for the apical auxin response maximum and the specification of apical embryonic structures. Later in embryogenesis, the precisely timed onset of localized apical auxin biosynthesis mediates PIN1 polarization, basal auxin response maximum, and specification of the root pole. Thus, the tight spatiotemporal control of distinct local auxin sources provides a necessary, non-cell-autonomous trigger for the coordinated cell polarization and subsequent apical-basal axis orientation during embryogenesis and, presumably, also for other polarization events during postembryonic plant life.

• MeSH
• Arabidopsis embryologie   MeSH
• kyseliny indoloctové metabolismus   farmakologie   MeSH
• membránové transportní proteiny metabolismus   MeSH
• proteiny huseníčku metabolismus   MeSH
• regulátory růstu rostlin metabolismus   farmakologie   fyziologie   MeSH
• rozvržení tělního plánu účinky léků   MeSH
• semena rostlinná účinky léků   růst a vývoj   MeSH
• transport proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH