Cell Polarity Signaling: Focus on Polar Auxin Transport

Gao, Xiaowei; Nagawa, Shingo; Wang, Gen‐Xuan; Yang, Zhenbiao

doi:10.1093/mp/ssn069

Cited by 29 publications

(30 citation statements)

References 100 publications

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“…In this study, the establishment of auxin gradients in embryonic callus was coincident with the marked polar distribution of PIN1, which was observed in edge regions of embryonic callus at 16 and 24 h (Figures 5a–c and 7a–c). This is consistent with a model indicating that auxin mediates PIN localization through a positive feedback mechanism to maintain the polarized localization of PINs (Gao et al. , 2008).…”

Section: Discussionsupporting

confidence: 92%

Auxin‐induced WUS expression is essential for embryonic stem cell renewal during somatic embryogenesis in Arabidopsis

et al. 2009

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Somatic embryogenesis requires auxin and establishment of the shoot apical meristem (SAM). WUSCHEL (WUS) is critical for stem cell fate determination in the SAM of higher plants. However, regulation of WUS expression by auxin during somatic embryogenesis is poorly understood. Here, we show that expression of several regulatory genes important in zygotic embryogenesis were up-regulated during somatic embryogenesis of Arabidopsis. Interestingly, WUS expression was induced within the embryonic callus at a time when somatic embryos could not be identified morphologically or molecularly. CorrectWUS expression, regulated by a defined critical level of exogenous auxin, is essential for somatic embryo induction. Furthermore, it was found that auxin gradients were established in specific regions that could then give rise to somatic embryos. The establishment of auxin gradients was correlated with the induced WUS expression. Moreover, the auxin gradients appear to activate PIN1 polar localization within the embryonic callus. Polarized PIN1 is probably responsible for the observed polar auxin transport and auxin accumulation in the SAM and somatic embryo. Suppression of WUS and PIN1 indicated that both genes are necessary for embryo induction through their regulation of downstream gene expression. Our results reveal that establishment of auxin gradients and PIN1-mediated polar auxin transport are essential for WUS induction and somatic embryogenesis. This study sheds new light on how auxin regulates stem cell formation during somatic embryogenesis.

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Section: Discussionsupporting

confidence: 92%

Auxin‐induced WUS expression is essential for embryonic stem cell renewal during somatic embryogenesis in Arabidopsis

et al. 2009

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“…During tube elongation, numerous cell materials such as the plasma membrane and cell wall materials required for tube extension are carried by secretion vesicles and transported to the right place. Compared to other types of plant cells, vesicle-mediated secretion and endocytosis in the growing pollen tube is much more active and vigorous (Gao et al, 2008;Li et al, 2008). Transport vesicles are secreted and move via cytoplasmic streaming towards the pollen tip, where they fuse with the PM and then are quickly retrieved back through endocytosis for a new round of transportation.…”

Section: Discussionmentioning

confidence: 99%

Vacuolar Sorting Receptor (VSR) Proteins Reach the Plasma Membrane in Germinating Pollen Tubes

et al. 2011

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Vacuolar sorting receptors (VSRs) are type I integral membrane proteins that mediate the vacuolar transport of soluble cargo proteins via prevacuolar compartments (PVCs) in plants. Confocal immunofluorescent and immunogold Electron Microscope (EM) studies have localized VSRs to PVCs or multivesicular bodies (MVBs) and trans-Golgi network (TGN) in various plant cell types, including suspension culture cells, root cells, developing and germinating seeds. Here, we provide evidence that VSRs reach plasma membrane (PM) in growing pollen tubes. Both immunofluorescent and immunogold EM studies with specific VSR antibodies show that, in addition to the previously demonstrated PVC/MVB localization, VSRs also localize to PM in lily and tobacco pollen tubes prepared from chemical fixation or high-pressure freezing/frozen substitution. Such a PM localization suggests an additional role of VSR proteins in mediating protein transport to PM and endocytosis in growing pollen tubes. Using a high-speed Spinning Disc Confocal Microscope, the possible fusion between VSR-positive PVC organelles and the PM was also observed in living tobacco pollen tubes transiently expressing the PVC reporter GFP-VSR. In contrast, the lack of a prominent PM localization of GFP-VSR in living pollen tubes may be due to the highly dynamic situation of vesicular transport in this fast-growing cell type.

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“…The rate of protein synthesis is key to cellular growth, and stimulation of the expression of genes encoding components of the translational apparatus occurs in cycling cells and upon the addition of auxin in plant cells (Trémousaygue et al, 2003;Gao et al, 2008). In multicellular organisms, it is debated whether the factors determining growth impose their influence on organs as a whole or whether they regulate growth and proliferation at the cellular level (Tsukaya and Beemster, 2006).…”

Section: Meja Maintains High Expression Of Ribosomal Genesmentioning

confidence: 99%

Jasmonate Controls Leaf Growth by Repressing Cell Proliferation and the Onset of Endoreduplication while Maintaining a Potential Stand-By Mode

et al. 2013

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Phytohormones regulate plant growth from cell division to organ development. Jasmonates (JAs) are signaling molecules that have been implicated in stress-induced responses. However, they have also been shown to inhibit plant growth, but the mechanisms are not well understood. The effects of methyl jasmonate (MeJA) on leaf growth regulation were investigated in Arabidopsis (Arabidopsis thaliana) mutants altered in JA synthesis and perception, allene oxide synthase and coi1-16B (for coronatine insensitive1), respectively. We show that MeJA inhibits leaf growth through the JA receptor COI1 by reducing both cell number and size. Further investigations using flow cytometry analyses allowed us to evaluate ploidy levels and to monitor cell cycle progression in leaves and cotyledons of Arabidopsis and/or Nicotiana benthamiana at different stages of development. Additionally, a novel global transcription profiling analysis involving continuous treatment with MeJA was carried out to identify the molecular players whose expression is regulated during leaf development by this hormone and COI1. The results of these studies revealed that MeJA delays the switch from the mitotic cell cycle to the endoreduplication cycle, which accompanies cell expansion, in a COI1-dependent manner and inhibits the mitotic cycle itself, arresting cells in G1 phase prior to the S-phase transition. Significantly, we show that MeJA activates critical regulators of endoreduplication and affects the expression of key determinants of DNA replication. Our discoveries also suggest that MeJA may contribute to the maintenance of a cellular "stand-by mode" by keeping the expression of ribosomal genes at an elevated level. Finally, we propose a novel model for MeJA-regulated COI1-dependent leaf growth inhibition.

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Cell Polarity Signaling: Focus on Polar Auxin Transport

Cited by 29 publications

References 100 publications

Auxin‐induced WUS expression is essential for embryonic stem cell renewal during somatic embryogenesis in Arabidopsis

Auxin‐induced WUS expression is essential for embryonic stem cell renewal during somatic embryogenesis in Arabidopsis

Vacuolar Sorting Receptor (VSR) Proteins Reach the Plasma Membrane in Germinating Pollen Tubes

Jasmonate Controls Leaf Growth by Repressing Cell Proliferation and the Onset of Endoreduplication while Maintaining a Potential Stand-By Mode

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