https://nova.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:41130 Wed 27 Jul 2022 10:35:19 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:171 Wed 22 Mar 2023 17:05:01 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:20021 Wed 22 Mar 2023 17:00:54 AEDT ]]> https://nova.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://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:6933 Wed 11 Apr 2018 15:29:30 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:20020 Wed 11 Apr 2018 14:02:44 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26903 Vicia faba cotyledons identified transfer cell specific transcriptomes associated with uniform wall and wall ingrowth deposition. All functional groups of genes examined were expressed before and following transition to a transfer cell fate. What changed were the isoform profiles of expressed genes within functional groups. Genes encoding ethylene and Ca²⁺ signal generation and transduction pathways were enriched during uniform wall construction. Auxin-and reactive oxygen species-related genes dominated during wall ingrowth formation and ABA genes were evenly expressed across ingrowth wall construction. Expression of genes encoding kinesins, formins and villins was consistent with reorganization of cytoskeletal components. Uniform wall and wall ingrowth specific expression of exocyst complex components and SNAREs suggested specific patterns of exocytosis while dynamin mediated endocytotic activity was consistent with establishing wall ingrowth loci. Key regulatory genes of biosynthetic pathways for sphingolipids and sterols were expressed across ingrowth wall construction. Transfer cell specific expression of cellulose synthases was absent. Rather xyloglucan, xylan and pectin biosynthetic genes were selectively expressed during uniform wall construction. More striking was expression of genes encoding enzymes for re-modelling/degradation of cellulose, xyloglucans, pectins and callose. Extensins dominated the cohort of expressed wall structural proteins and particularly so across wall ingrowth development. Ion transporters were selectively expressed throughout ingrowth wall development along with organic nitrogen transporters and a large group of ABC transporters. Sugar transporters were less represented. Conclusions: Pathways regulating signalling and intracellular organization were fine tuned whilst cell wall construction and membrane transporter profiles were altered substantially upon transiting to a transfer cell fate. Each phase of ingrowth wall construction was linked with unique cohorts of expressed genes.]]> Wed 11 Apr 2018 13:16:39 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26902 2+ levels at loci where wall ingrowth papillae are deposited. The physiological significance of the depletion zones as a mechanism to accommodate the construction of wall ingrowth papillae without compromising maintenance of the plasma membrane-microtubule inter-relationship is discussed.]]> Wed 11 Apr 2018 12:43:42 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:27813 Wed 11 Apr 2018 12:10:22 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:47611 Vicia faba cotyledons. When these cotyledons are placed in culture, their adaxial epidermal cells trans-differentiate to a TC phenotype regulated by auxin, ethylene, extracellular hydrogen peroxide (_apoH₂O₂), and cytosolic Ca²⁺ ([Ca²⁺]_cyt) arranged in series. Staining cultured cotyledons with the sterol-specific dye, Filipin III, detected a polarized sterol-enriched domain in the plasma membrane of their trans-differentiating epidermal transfer cells (ETCs). Ethylene activated sterol biosynthesis while extracellular _apoH₂O₂ directed sterol-enriched vesicles to fuse with the outer periclinal region of the ETC plasma membrane. The sterol-enriched domain was essential for generating the [Ca²⁺]_cyt signal and orchestrating construction of both the uniform wall layer and wall ingrowth papillae. A model is presented outlining how the sterol-enriched plasma membrane domain forms and functions to regulate wall labyrinth assembly.]]> Tue 24 Jan 2023 11:28:41 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:55004 Thu 28 Mar 2024 13:31:01 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:508 Thu 25 Jul 2013 09:10:26 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:228 Thu 25 Jul 2013 09:09:23 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:33602 Sorghum bicolor SUTs SbSUT1 and SbSUT5 were characterized by determining their transport properties heterologously expressed in yeast or Xenopus laevis oocytes, and their in planta cellular and subcellular localization. The plasma membrane-localized SbSUT1 and SbSUT5 exhibited a strong selectivity for Suc and high Suc affinities in X. laevis oocytes at pH 5—SbSUT1, 6.3 ± 0.7 mm, and SbSUT5, 2.4 ± 0.5 mm Suc. The Suc affinity of SbSUT1 was dependent on membrane potential and pH. In contrast, SbSUT5 Suc affinity was independent of membrane potential and pH but supported high transport rates at neutral pH. Suc transport by the tonoplast localized SbSUT4 could not be detected using yeast or X. laevis oocytes. Across internode development, SUTs, other than SbSUT4, were immunolocalized to sieve elements, while for elongating and recently elongated internodes, SUTs also were detected in storage parenchyma cells. We conclude that apoplasmic Suc unloading from de-energized protophloem sieve elements in meristematic zones may be mediated by reversal of SbSUT1 and/or by uniporting SWEETs. Storage parenchyma localized SbSUT1 and SbSUT5 may accumulate Suc from the stem apoplasms of elongating and recently elongated internodes, whereas SbSUT4 may function to release Suc from vacuoles. Transiting from an apoplasmic to symplasmic unloading pathway as the stem matures, SbSUT1 and SbSUT5 increasingly function in Suc retrieval into metaphloem sieve elements to maintain a high turgor to drive symplasmic unloading by bulk flow.]]> Thu 22 Nov 2018 16:43:24 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:31279 Sorghum bicolor, was evaluated during different stages of internode development. Transcript levels and functional properties of selected key transporters were measured, with both cellular and subcellular localization determined.]]> Thu 22 Nov 2018 16:23:38 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:9443 Sat 24 Mar 2018 08:41:33 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:6985 Sat 24 Mar 2018 08:37:50 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:9649 Sat 24 Mar 2018 08:35:25 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1974 Sat 24 Mar 2018 08:33:16 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1319 Sat 24 Mar 2018 08:32:32 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1116 Sat 24 Mar 2018 08:32:07 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1677 Sat 24 Mar 2018 08:30:25 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1437 Sat 24 Mar 2018 08:28:14 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:1434 Sat 24 Mar 2018 08:28:04 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:13244 Sat 24 Mar 2018 08:16:01 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:10715 Sat 24 Mar 2018 08:08:27 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:5447 Sat 24 Mar 2018 07:48:13 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26365 Sorghum bicolor(L.) Moench were deduced from histochemical determinations of cell wall composition and from the relative radial mobilities of fluorescent tracer dyes exiting vascular pipelines. The cell walls of small vascular bundles in source leaves, the predicted site of phloem loading, contained minimal quantities of lignin and suberin. A phloem-loaded symplasmic tracer, carboxyfluorescein, was retained within the collection phloem, indicating symplasmic isolation. Together, these findings suggested that phloem loading in source leaves occurs apoplasmically. Lignin was restricted to the walls of protoxylem elements located in meristematic, elongating and recently elongated regions of the stem. The apoplasmic tracer, 8-hydroxypyrene-1,3,6-trisulfonic acid, moved radially from the transpiration stream, consistent with phloem and storage parenchyma cells being interconnected by an apoplasmic pathway. The major phase of sucrose accumulation in mature stems coincided with heavy lignification and suberisation of sclerenchyma sheath cell walls restricting apoplasmic tracer movement from the phloem to storage parenchyma apoplasms. Phloem unloading at this stage of stem development followed a symplasmic route linking sieve elements and storage parenchyma cells, as confirmed by the phloem-delivered symplasmic tracer, 8-hydroxypyrene-1,3,6-trisulfonic acid, moving radially from the stem phloem.]]> Sat 24 Mar 2018 07:33:08 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26958 Solanum lycopersicum) with its CWIN inhibitor gene silenced and focusing on ovaries and fruits at 2 d before and after pollination, respectively. We found that the increase of CWIN activity suppressed LMHS-induced programmed cell death in fruits. Surprisingly, measurement of the contents of H₂O₂ and malondialdehyde and the activities of a cohort of antioxidant enzymes revealed that the CWIN-mediated inhibition on programmed cell death is exerted in a reactive oxygen species-independent manner. Elevation of CWIN activity sustained Suc import into fruits and increased activities of hexokinase and fructokinase in the ovaries in response to LMHS. Compared to the wild type, the CWIN-elevated transgenic plants exhibited higher transcript levels of heat shock protein genes Hsp90 and Hsp100 in ovaries and HspII17.6 in fruits under LMHS, which corresponded to a lower transcript level of a negative auxin responsive factor IAA9 but a higher expression of the auxin biosynthesis gene ToFZY6 in fruits at 2 d after pollination. Collectively, the data indicate that CWIN enhances fruit set under LMHS through suppression of programmed cell death in a reactive oxygen species-independent manner that could involve enhanced Suc import and catabolism, HSP expression, and auxin response and biosynthesis.]]> Sat 24 Mar 2018 07:27:01 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:26905 Sat 24 Mar 2018 07:23:35 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:24087 Corymbia maculata. The higher rate of fertilizer addition improved seedling establishment of Mimosaceae and the survival of Myrtaceae species. High nutrient treatments increased weed and grass densities, which may have reduced the nutrient benefit for native species. In conclusion, biosolids and the high rate of fertilizer application ameliorated the nitrogen and phosphorus deficiency of spoil to support growth and survival of reintroduced native species. However, potential benefits were attenuated by competition from accompanying weed growth that could be managed by implementing a control program.]]> Sat 24 Mar 2018 07:11:47 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32463 2+ regulates wall labyrinth assembly. To identify gene cohorts regulated by each signal, a RNA- sequencing study was undertaken using Vicia faba cotyledons. When cotyledons are placed in culture, their adaxial epidermal cells spontaneously undergo trans-differentiation to epidermal TCs (ETCs). Expressed genes encoding proteins central to wall labyrinth formation (signaling, intracellular organization, cell wall) and TC function of nutrient transport were assembled. Transcriptional profiles identified 9,742 annotated ETC-specific differentially expressed genes (DEGs; Log₂fold change > 1; FDR p ≤ 0.05) of which 1,371 belonged to signaling (50%), intracellular organization (27%), cell wall (15%) and nutrient transporters (9%) functional categories. Expression levels of 941 ETC-specific DEGs were found to be sensitive to the known signals regulating ETC trans-differentiation. Significantly, signals acting alone, or in various combinations, impacted similar numbers of ETC-specific DEGs across the four functional gene categories. Amongst the signals acting alone, H₂O₂ exerted most influence affecting expression levels of 56% of the ETC-specific DEGs followed by Ca²⁺ (21%), auxin (18%) and ethylene (5%). The dominance by H₂O₂ was evident across all functional categories, but became more attenuated once trans-differentiation transitioned into WI papillae formation. Amongst the eleven signal combinations, H₂O₂/Ca²⁺ elicited the greatest impact across all functional categories accounting for 20% of the ETC-specific DEG cohort. The relative influence of the other signals acting alone, or in various combinations, varied across the four functional categories and two phases of wall labyrinth construction. These transcriptome data provide a powerful information platform from which to examine signal transduction pathways and how these regulate expression of genes encoding proteins engaged in intracellular organization, cell wall construction and nutrient transport.]]> Mon 23 Sep 2019 12:07:21 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32294 Vicia faba cotyledon culture system. On transfer of cotyledons to culture, their adaxial epidermal cells spontaneously trans-differentiate to a reticulate architecture comparable to their abaxial epidermal transfer cell counterparts formed in planta. Uniform wall layer construction commenced once adaxial epidermal cell expansion had ceased to overlay the original outer periclinal wall on its inner surface. In contrast to the dense ring-like lattice of cellulose microfibrils in the original primary wall, the uniform wall layer was characterized by a sparsely dispersed array of linear cellulose microfibrils. A re-modeled cortical microtubule array exerted no influence on uniform wall layer formation or on its cellulose microfibril organization. Surprisingly, formation of the uniform wall layer was not dependent upon depositing a cellulose scaffold. In contrast, uniform wall cellulose microfibrils were essential precursors for constructing wall ingrowth papillae. On converging to form wall ingrowth papillae, the cellulose microfibril diameters increased 3-fold. This event correlated with up-regulated differential, and transfer-cell specific, expression of VfCesA3B while transcript levels of other cellulose biosynthetic-related genes linked with primary wall construction were substantially down-regulated.]]> Mon 23 Sep 2019 11:50:11 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:32466 2+ define loci at which WI papillae form in developing adaxial epidermal transfer cells of Vicia faba cotyledons that are induced to trans-differentiate when the cotyledons are placed on culture medium. We evaluated the hypothesis that vesicle trafficking along a Ca²⁺-regulated remodelled actin network is the mechanism that underpins this outcome. Polarized to the outer periclinal cytoplasm, a Ca²⁺-dependent remodelling of long actin bundles into short, thin bundles was found to be essential for assembling WI papillae but not the underlying uniform wall layer. The remodelled actin network directed polarized vesicle trafficking to sites of WI papillae construction, and a pharmacological study indicated that both exo- and endocytosis contributed to assembly of the papillae. Potential candidates responsible for the Ca²⁺-dependent actin remodelling, along with those underpinning polarized exo- and endocyotosis, were identified in a transcriptome RNAseq database generated from the trans-differentiating epidermal cells. Of most significance, endocytosis was controlled by up-regulated expression of a dynamin-like isoform. How a cycle of localized exo- and endocytosis, regulated by Ca²⁺-dependent actin remodelling, assembles WI papillae is discussed.]]> Mon 23 Sep 2019 10:09:31 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:18693 Mon 20 Jul 2015 17:41:44 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:46193 Vicia faba cotyledons, when placed in culture, undergo a rapid (hours) trans-differentiation to a functional epidermal transfer cell (ETC) phenotype. The trans-differentiation event is controlled by a signalling cascade comprising auxin, ethylene, apoplasmic reactive oxygen species (_apoROS), and cytosolic Ca²⁺. Apoplasmic hydrogen peroxide (_apoH₂O₂) was confirmed as the _apoROS regulating UWL and WI papillae formation. Informed by an ETC-specific transcriptome, a pharmacological approach identified a temporally changing cohort of H₂O₂ biosynthetic enzymes. The cohort contained a respiratory burst oxidase homologue, polyamine oxidase, copper amine oxidase, and a suite of class III peroxidases. Collectively these generated two consecutive bursts in _apoH₂O₂ production. Spatial organization of biosynthetic/catabolic enzymes was deduced from responses to pharmacologically blocking their activities on the cellular and subcellular distribution of _apoH₂O₂. The findings were consistent with catalase activity constraining the _apoH₂O₂ signal to the outer periclinal wall of the ETCs. Strategic positioning of class III peroxidases in this outer domain shaped subcellular _apoH₂O₂ signatures that differed during assembly of the UWL and WI papillae.]]> Mon 14 Nov 2022 11:15:50 AEDT ]]>