https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:26914 cyt) of cells trans-differentiating to a transfer cell morphology was tested. This hypothesis was examined using Vicia faba cotyledons. On transferring cotyledons to culture, their adaxial epidermal cells synchronously trans-differentiate to epidermal transfer cells. A polarized and persistent Ca²⁺ signal, generated during epidermal cell trans-differentiation, was found to co-localize with the site of ingrowth wall formation. Dampening Ca²⁺ signal intensity, by withdrawing extracellular Ca²⁺ or blocking Ca²⁺ channel activity, inhibited formation of wall ingrowth papillae. Maintenance of Ca²⁺ signal polarity and persistence depended upon a rapid turnover (minutes) of cytosolic Ca²⁺ by co-operative functioning of plasma membrane Ca²⁺-permeable channels and Ca²⁺-ATPases. Viewed paradermally, and proximal to the cytosol-plasma membrane interface, the Ca²⁺ signal was organized into discrete patches that aligned spatially with clusters of Ca²⁺-permeable channels. Mathematical modelling demonstrated that these patches of cytosolic Ca²⁺ were consistent with inward-directed plumes of elevated [Ca²⁺]_cyt. Plume formation depended upon an alternating distribution of Ca²⁺-permeable channels and Ca²⁺-ATPase clusters. On further inward diffusion, the Ca²⁺ plumes coalesced into a uniform Ca²⁺ signal. Blocking or dispersing the Ca²⁺ plumes inhibited deposition of wall ingrowth papillae, while uniform wall formation remained unaltered. A working model envisages that cytosolic Ca²⁺ plumes define the loci at which wall ingrowth papillae are deposited.]]> Wed 11 Apr 2018 16:31:50 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:24956 Vicia faba. Comparing cotyledons cultured for 0, 3, 9, and 24 h to induce trans-differentiation of epidermal TCs identified 43 transcription factors that showed either epidermal-specific or epidermal-enhanced expression, and 10 that showed epidermal-specific down regulation. Members of the WRKY and ethylene-responsive families were prominent in the cohort of transcription factors showing epidermal-specific or epidermal-enhanced expression, consistent with the initiation of TC development often representing a response to stress. Members of the MYB family were also prominent in these categories, including orthologs of MYB genes involved in localized secondary wall deposition in Arabidopsis thaliana. Among the group of transcription factors showing down regulation were various homeobox genes and members of the MADs-box and zinc-finger families of poorly defined functions. Collectively, this study identified several transcription factors showing expression characteristics and orthologous functions that indicate likely participation in transcriptional regulation of epidermal TC development in V. faba cotyledons.]]> Wed 11 Apr 2018 10:50:02 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:21810 trans-differentiation events leading to formation of TC ingrowth walls are poorly understood. Vicia faba cotyledons offer a robust experimental model to examine TC induction as, when placed into culture, their adaxial epidermal cells rapidly (h) and synchronously form polarized ingrowth walls accessible for experimental observations. Using this model, we recently reported findings consistent with extracellular hydrogen peroxide, produced through a respiratory burst oxidase homolog/superoxide dismutase pathway, initiating cell wall biosynthetic activity and providing directional information guiding deposition of the polarized uniform wall. Our conclusions rested on observations derived from pharmacological manipulations of hydrogen peroxide production and correlative gene expression data sets. A series of additional studies were undertaken, the results of which verify that extracellular hydrogen peroxide contributes to regulating ingrowth wall formation and is generated by a respiratory burst oxidase homolog/superoxide dismutase pathway.]]> Sat 24 Mar 2018 07:59:23 AEDT ]]>