ORCID Profile
0000-0003-2456-1227
Current Organisations
CSIRO
,
CSIRO Queensland Bioscience Precinct
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Springer Science and Business Media LLC
Date: 2003
Publisher: Elsevier BV
Date: 05-2010
DOI: 10.1016/J.PHYTOCHEM.2010.01.014
Abstract: Sugarcane (a Saccharum spp. interspecific hybrid) was previously engineered to synthesize sorbitol (designated as sorbitolcane). Motivated by the atypical development of the leaves in some sorbitolcane, the polar metabolite profiles in the leaves of those plants were compared against a group of control sugarcane plants. Eighty-six polar metabolites were detected in leaf extracts by GC-MS. Principal component analysis of the metabolites indicated that three compounds were strongly associated with sorbitolcane. Two were identified as sorbitol and gentiobiose and the third was unknown. Gentiobiose and the unknown compound were positively correlated with sorbitol accumulation. The unknown compound was only abundant in sorbitolcane. This compound was structurally characterized and found to be a sorbitol-glucose conjugate. (13)C NMR analysis indicated that the glucopyranose and glucitol moieties were 1,6-linked. Ligand exchange chromatography confirmed that the compound was a beta-anomer, thus identifying the compound as 6-O-beta-d-glucopyranosyl-D-glucitol, or gentiobiitol.
Publisher: Wiley
Date: 13-09-2018
DOI: 10.1111/PPL.12786
Abstract: Calcium (Ca
Publisher: Oxford University Press (OUP)
Date: 19-07-2013
DOI: 10.1093/JXB/ERT205
Publisher: Elsevier BV
Date: 1995
DOI: 10.1016/0168-1656(94)00133-W
Abstract: A Neocallimastix patriciarum xylanase cDNA with the core coding sequence essentially identical to xynA was isolated and modified for high-level expression in Escherichia coli. The xylanase cDNA was truncated into in idual catalytic domains, which were modified at the N-terminus. These modified xylanases were synthesised as non-fusion proteins under the control of the tac promoter. High-level expression was obtained with the modified domain II construct, accounting for approx. 25% of total cellular protein. However, with the same vector and expression cassette, expression levels of constructs containing domain I or domains I and II fused in tandem were very low. RNA analysis revealed that the striking difference in expression levels of these three constructs was not due to transcription efficiency, but was mainly related to transcript stability. Further analysis of the domain II construct revealed that the high-level expression of the domain II xylanase was largely attributed to the presence of a favourable N-terminal coding sequence, as mutation at the N-terminus of the domain II dramatically reduced the expression level. The modified domain II xylanase produced in E. coli had a specific activity of 1229 U mg-1 protein at pH 7 and 50 degrees C without purification. The availability of a recombinant fungal xylanase with high specific activity and in high yield offers a potentially attractive source of xylanase for industrial applications.
Publisher: Springer Science and Business Media LLC
Date: 22-08-2020
Publisher: Springer Science and Business Media LLC
Date: 26-02-2021
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/FP17073
Abstract: The role of ShSUT1 in sucrose mobilisation and storage in sugarcane was investigated by employing RNAi technology to reduce the expression of this gene. Transcript profiling in non-transformed plants showed an alignment between expression and sucrose concentration, with strongest expression in source leaves and increasing expression through the daylight period of a diurnal cycle. Five transgenic plant lines were produced with reduced ShSUT1 expression ranging from 52 to 92% lower than control plants. Differential suppression of ShSUT1 sequence variants in the highly polyploid sugarcane genome were also investigated. Amplicon sequencing of the ShSUT1 variants within the transgenic lines and controls showed no preferential suppression with only minor differences in the proportional expression of the variants. A range of altered sugar, fibre and moisture contents were measured in mature leaf and internode s les, but no phenotype was consistently exhibited by all five transgenic lines. Phenotypes observed indicate that ShSUT1 does not play a direct role in phloem loading. ShSUT1 is likely involved with retrieving sucrose from intercellular spaces for transport and storage.
Publisher: Frontiers Media SA
Date: 03-05-2018
Publisher: Springer Science and Business Media LLC
Date: 11-2013
DOI: 10.1007/S11103-012-9983-1
Abstract: Fructans represent the major component of water soluble carbohydrates (WSCs) in the maturing stem of temperate cereals and are an important temporary carbon reserve for grain filling. To investigate the importance of source carbon availability in fructan accumulation and its molecular basis, we performed comparative analyses of WSC components and the expression profiles of genes involved in major carbohydrate metabolism and photosynthesis in the flag leaves of recombinant inbred lines from wheat cultivars Seri M82 and Babax (SB lines). High sucrose levels in the mature flag leaf (source organ) were found to be positively associated with WSC and fructan concentrations in both the leaf and stem of SB lines in several field trials. Analysis of Affymetrix expression array data revealed that high leaf sucrose lines grown in abiotic-stress-prone environments had high expression levels of a number of genes in the leaf involved in the sucrose synthetic pathway and photosynthesis, such as Calvin cycle genes, antioxidant genes involved in chloroplast H(2)O(2) removal and genes involved in energy dissipation. The expression of the majority of genes involved in fructan and starch synthetic pathways were positively correlated with sucrose levels in the leaves of SB lines. The high level of leaf fructans in high leaf sucrose lines is likely attributed to the elevated expression levels of fructan synthetic enzymes, as the mRNA levels of three fructosyltransferase families were consistently correlated with leaf sucrose levels among SB lines. These data suggest that high source strength is one of the important genetic factors determining high levels of WSC in wheat.
Publisher: Springer Science and Business Media LLC
Date: 27-10-2013
Publisher: Canadian Science Publishing
Date: 07-2007
DOI: 10.1139/B07-070
Abstract: The completed rice-genome sequence was screened with a known inorganic phosphate (Pi) transporter sequence to reveal a family of 13 Pi transporters. This family can be used for studies into Pi acquisition and translocation throughout the plant. Plants that form symbiotic associations with arbuscular mycorrhizal (AM) fungi are of particular interest with respect to Pi acquisition because of their ability to utilize both direct and fungal pathways of uptake. Localization of transcripts of two Pi transporters by real-time RT-PCR and in situ hybridization were conducted in rice subjected to low Pi, high Pi, and AM colonization. One Pi transporter, ORYsa Pht1 , was detected in rice roots under all growth conditions. ORYsa Pht1 was only expressed in roots colonized by AM fungi. Antisense RNA probes of ORYsa Pht1 localized to cortical cells containing arbuscules and hyphal coils, formed by Glomus intraradices Schenck and Smith and Scutellospora calospora (Nicolson and Gerdemann) Walker and Sanders, respectively. Localization of the ORYsa Pht1 probes was similar to that observed for ORYsa Pht1 in colonized rice roots. This research proposes that at least two rice Pi transporters are involved in acquiring Pi via AM fungi, emphasising the complexity of Pi acquisition in plants with access to two Pi uptake pathways.
Publisher: Elsevier BV
Date: 03-2017
Publisher: Springer Science and Business Media LLC
Date: 26-02-2008
DOI: 10.1007/S11103-008-9311-Y
Abstract: Water deficit in plants causes a reduction in photosynthesis and high demands for osmolyte synthesis. To elucidate regulation of carbohydrate metabolic genes in wheat (Triticum aestivum) leaves during drought stress, we performed a systematic expression study using quantitative RT-PCR and cDNA microarray. These analyses revealed that expression levels of most genes encoding chloroplast enzymes involved in carbon fixation (Calvin cycle) were reduced in the leaves during prolonged drought stress. Transcript levels of highly expressed isoenzymes of hexokinase and fructokinase also decreased. Conversely, genes encoding cytoplasmic and vacuolar enzymes in the pathways leading to glucose, fructose and fructan production were up-regulated in the stressed leaves. Systematic expression analysis of an almost complete set of genes involved in conversion of triose phosphates to hexoses and hexose phosphorylation showed that isoenzymes of many enzymes were differentially regulated during drought stress. Correlation analysis indicated that the drought down-regulated Calvin cycle genes were coordinately regulated. This coordinated down-regulation extended to genes encoding major isoenzymes of chloroplast triosephosphate hosphate translocator, cytoplasmic fructose-1,6-bisphosphate aldolase and fructose bisphosphatase. Highly correlated expression was also observed between drought up-regulated genes involved in sucrose synthesis and hydrolysis or fructan synthesis. These data dissect coordination in regulation of key enzyme genes involved in carbon fixation and accumulation of hexoses and fructans and provide an insight into molecular mechanisms at the transcript level underlying changes in carbohydrate metabolism in wheat adaptation to drought stress.
Publisher: No publisher found
Date: 2010
Publisher: Oxford University Press (OUP)
Date: 04-2007
DOI: 10.1093/PCP/PCM027
Abstract: Sucrose content increases with internode development down the stem of sugarcane. In an attempt to determine which other changes in metabolites may be linked to sucrose accumulation gas chromatography-mass spectrometry was used to obtain metabolic profiles from methanol/water extracts of four s les of different age down the stem of cultivar Q117. Extracts were derivatized with either N-methyl-N-(trimethylsilyl) trifluoracetamide (TMS) or N-methyl N-(tert-butyldimethylsilyl) trifluoroacetamide (TBS) separately in order to increase the number of metabolites that could be detected. This resulted in the measurement of 121 and 71 metabolites from the TMS and TBS derivatization, respectively. Fifty-five metabolites were identified using commercial and publicly available libraries. Statistical analysis of the metabolite profiles resulted in clustering of tissue types. Particular metabolites were correlated with the level of sucrose accumulation, which as expected increased down the stem. Metabolites, such as tricarboxylic acid cycle intermediates and amino acids, were more abundant in the M2 s le (meristem to internode 2) that was actively growing and decreased in an apparently coordinated developmentally programmed manner in more mature internodes down the stem. However, other metabolites such as trehalose and raffinose showed positive correlations with sucrose concentration. Here we discuss the technique used to measure metabolites in sugarcane and the changes in metabolite abundance down the sugarcane stem.
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/FP18136
Abstract: The genetic network resulting in the production of an inflorescence is complex, involving one or more pathways including the photoperiod, maturity, gibberellin and autonomous pathways, and induction and repression of genes along the pathways. Understanding the cyclic expression profile of genes involved with photoperiod perception and floral pathway induction in sugarcane, an intermediate–short day plant (ISD), is crucial for identifying key genes and understanding how the profile changes in response to floral induction signals under decreasing daylengths. Homologues of 21 genes, and some gene alleles, associated with photoperiod perception and the flower induction pathway were examined in sugarcane variety Q174 over a 24-h light-dark cycle. The strongest expression of these genes was seen in the immature spindle leaves and levels of expression generally decreased with increasing leaf age. Significant changes in gene expression levels during a 24-h cycle were observed for 16 of the 21 genes tested. We have now defined an important baseline for expression patterns over a 24-h cycle in non-inductive conditions in sugarcane. These results can be utilised to select the optimal time for detecting changes during floral induction, differences between varieties that are responsive/non-responsive to photoperiod induction, and to identify genes that may be manipulated to enhance or inhibit flowering.
Publisher: The Royal Society
Date: 25-09-2019
Abstract: Plant species, populations and communities are under threat from climate change, invasive pathogens, weeds and habitat fragmentation. Despite considerable research effort invested in genome engineering for crop improvement, the development of genetic tools for the management of wild plant populations has rarely been given detailed consideration. Gene drive systems that allow direct genetic management of plant populations via the spread of fitness-altering genetic modifications could be of great utility. However, despite the rapid development of synthetic tools and their enormous promise, little explicit consideration has been given to their application in plants and, to date, they remain untested. This article considers the potential utility of gene drives for the management of wild plant populations, and examines the factors that might influence the design, spread and efficacy of synthetic drives. To gain insight into optimal ways to design and deploy synthetic drive systems, we investigate the ersity of mechanisms underlying natural gene drives and their dynamics within plant populations and species. We also review potential approaches for engineering gene drives and discuss their potential application to plant genomes. We highlight the importance of considering the impact of plant life-history and genetic architecture on the dynamics of drive, investigate the potential for different types of resistance evolution, and touch on the ethical, regulatory and social challenges ahead.
Publisher: Springer Science and Business Media LLC
Date: 30-03-2010
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/AR06042
Abstract: Sugarcane grown in the Ord River district of Western Australia has lower sucrose content than expected from earlier trials and experience in other irrigated districts. High temperatures have been hypothesised as a possible cause. The effects of high temperature (above 32°C) on growth and carbon partitioning were investigated. A temperature regime of (25–38°C) was compared with (23–33°C). In one experiment, 7-month-old plants of cvv. Q117 and Q158 were subjected to the treatments for 2 months. In another experiment, the plants were allowed to regrow (ratoon) for 6 months. In both experiments, the higher temperature resulted in more, shorter internodes and higher moisture content. Most internodes from plants in the higher temperature treatment had lower sucrose content than internodes from the lower temperature. On a dry mass basis the internodes from the plants in the higher temperature had proportionately more fibre and hexoses but lower sucrose. Combined with an increased number of nodes in a stem of similar or shorter length this would result in higher stalk fibre and lower sucrose content. The data provided evidence that sugarcane partitions less carbon to stored sucrose when grown under high compared with low temperatures. The two cultivars partitioned carbon between soluble (sugars) and insoluble (fibre) fractions to different degrees. These experiments also indicate that the current models describing leaf appearance and perhaps sugarcane growth at temperatures above 32°C, in general, need revision.
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/CP15009
Abstract: Sugarcane (Poaceae) has not undergone any commercial selection based upon seed characteristics. As the plant is grown from vegetative cuttings and the stalk harvested for its sucrose content, relatively little is known about its seed compared with other grass crops. The seeds of sugarcane were small, 1.8 × 0.8 mm, and the embryo comprised about one-third of the seed volume. Among the s les analysed, the seed contained on average 37%, 20% and 10% of the fresh weight as starch, protein and lipid, respectively. Histochemical staining showed that the starch was confined to the endosperm and the lipid to the embryo and aleurone layer. Protein was found in the embryo, endosperm and aleurone layer. There were small but significant differences between the sources of sugarcane seed. The wild relative S. spontaneum had significantly less starch than the commercial hybrid sugarcane seed. The lipid content was higher for sugarcane seed than for the seeds of many other grasses, possibly because of the high ratio of lipid-containing embryo to endosperm. Following artificial ageing, the observed decline in seed viability was not closely reflected by any significant changes in composition, although protein and sugars were reduced after 168 h. These results contribute to our understanding of the sexual reproductive biology of sugarcane, which is important for the science-based environmental risk evaluation of the release of genetically modified sugarcane.
Publisher: No publisher found
Date: 2017
Publisher: Oxford University Press (OUP)
Date: 14-12-2008
Abstract: Water-soluble carbohydrates (WSCs composed of mainly fructans, sucrose [Suc], glucose [Glc], and fructose) deposited in wheat (Triticum aestivum) stems are important carbon sources for grain filling. Variation in stem WSC concentrations among wheat genotypes is one of the genetic factors influencing grain weight and yield under water-limited environments. Here, we describe the molecular dissection of carbohydrate metabolism in stems, at the WSC accumulation phase, of recombinant inbred Seri/Babax lines of wheat differing in stem WSC concentrations. Affymetrix GeneChip analysis of carbohydrate metabolic enzymes revealed that the mRNA levels of two fructan synthetic enzyme families (Suc:Suc 1-fructosyltransferase and Suc:fructan 6-fructosyltransferase) in the stem were positively correlated with stem WSC and fructan concentrations, whereas the mRNA levels of enzyme families involved in Suc hydrolysis (Suc synthase and soluble acid invertase) were inversely correlated with WSC concentrations. Differential regulation of the mRNA levels of these Suc hydrolytic enzymes in Seri/Babax lines resulted in genotypic differences in these enzyme activities. Down-regulation of Suc synthase and soluble acid invertase in high WSC lines was accompanied by significant decreases in the mRNA levels of enzyme families related to sugar catabolic pathways (fructokinase and mitochondrion pyruvate dehydrogenase complex) and enzyme families involved in erting UDP-Glc to cell wall synthesis (UDP-Glc 6-dehydrogenase, UDP-glucuronate decarboxylase, and cellulose synthase), resulting in a reduction in cell wall polysaccharide contents (mainly hemicellulose) in the stem of high WSC lines. These data suggest that differential carbon partitioning in the wheat stem is one mechanism that contributes to genotypic variation in WSC accumulation.
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/CP09262
Abstract: While substantial effort has been expended on molecular techniques in an attempt to break through the apparent ceiling for sucrose content (SC) in sugarcane stalks, molecular processes and genetics limiting sucrose accumulation remain unclear. Our own studies indicate that limiting expansive growth with water stress will enhance sucrose accumulation in both low- and high-sucrose clones. Sucrose accumulation was largely explained (72%) by an equation with terms for photosynthesis, plant extension rate (PER), and plant number. New research was conducted to determine if this simple model stands when using temperature rather than water stress to perturb the source–sink balance. We also applied a thinning treatment to test the proposal implicit in this equation that SC will increase if competition between plants for photo-assimilate is reduced. Four clones from a segregating population representing extremes in SC were planted in pots and subjected to warm and cool temperature regimes in a glasshouse facility. A thinning treatment was imposed on half the pots by removing all but 6 shoots per pot. Temperature as a means of reducing sink strength seemed initially to be more successful than water regime because PER was 43% lower in the cool than in the hot regime while photosynthesis was only 14% less. PER was a good indicator of dry matter allocation to expansive growth, limited by water stress but not by temperature, because stalks tended to thicken in low temperature. Thinning had little effect on any of the attributes measured. Nevertheless the clonal variation in plant numbers and the response of PER to temperature helped to explain at least 69% of the variation in sucrose accumulation observed in this experiment. Thus the earlier model for sucrose accumulation appeared to be valid for the effect on sucrose accumulation of both temperature and water stress on the source–sink balance. The next step is to include internodes in models of assimilate partitioning to help understand the limiting steps in sucrose accumulation from the basics of source–sink dynamics.
Publisher: Wiley
Date: 25-01-2007
DOI: 10.1111/J.1467-7652.2006.00235.X
Abstract: An efficient in planta sugarcane-based production system may be realized by coupling the synthesis of alternative products to the metabolic intermediates of sucrose metabolism, thus taking advantage of the sucrose-producing capability of the plant. This was evaluated by synthesizing sorbitol in sugarcane (Saccharum hybrids) using the Malus domestica sorbitol-6-phosphate dehydrogenase gene (mds6pdh). Mature transgenic sugarcane plants were compared with untransformed sugarcane variety Q117 by evaluation of the growth, metabolite levels and extractable activity of relevant enzymes. The average amounts of sorbitol detected in the most productive line were 120 mg/g dry weight (equivalent to 61% of the soluble sugars) in the leaf lamina and 10 mg/g dry weight in the stalk pith. The levels of enzymes involved in sucrose synthesis and cleavage were elevated in the leaves of plants accumulating sorbitol, but this did not affect sucrose accumulation in the culm. The activity of oxidative reactions in the pentose phosphate pathway and the non-reversible glyceraldehyde-3-phosphate dehydrogenase reaction were elevated to replenish the reducing power consumed by sorbitol synthesis. Sorbitol-producing sugarcane generated 30%-40% less aerial biomass and was 10%-30% shorter than control lines. Leaves developed necrosis in a pattern characteristic of early senescence, and the severity was related to the relative quantity of sorbitol accumulated. When the Zymomonas mobilis glucokinase (zmglk) gene was co-expressed with mds6pdh to increase the production of glucose-6-phosphate, the plants were again smaller, indicating that glucose-6-phosphate deficiency was not responsible for the reduced growth. In summary, sorbitol hyperaccumulation affected sugarcane growth and metabolism, but the outcome was not lethal for the plant. This work also demonstrated that impressive yields of alternative products can be generated from the intermediates of sucrose metabolism in Saccharum spp.
Publisher: Springer Science and Business Media LLC
Date: 25-08-2005
DOI: 10.1007/S00425-005-0015-0
Abstract: A very large number of plant species are capable of forming symbiotic associations with arbuscular mycorrhizal (AM) fungi. The roots of these plants are potentially capable of absorbing P from the soil solution both directly through root epidermis and root hairs, and via the AM fungal pathway that delivers P to the root cortex. A large number of phosphate (P) transporters have been identified in plants tissue expression patterns and kinetic information supports the roles of some of these in the direct root uptake pathways. Recent work has identified additional P transporters in several unrelated species that are strongly induced, sometimes specifically, in AM roots. The primary aim of the work described in this paper was to determine how mycorrhizal colonisation by different species of AM fungi influenced the expression of members of the Pht1 gene families in the cereals Hordeum vulgare (barley), Triticum aestivum (wheat) and Zea mays (maize). RT-PCR and in-situ hybridisation, showed that the transporters HORvu Pht1 (AY187023), TRIae Pht1 myc (AJ830009) and ZEAma Pht1 (AJ830010), had increased expression in roots colonised by the AM fungi Glomus intraradices,Glomus sp. WFVAM23 and Scutellospora calospora. These findings add to the increasing body of evidence indicating that plants that form AM associations with members of the Glomeromycota have evolved phosphate transporters that are either specifically or preferentially involved in scavenging phosphate from the apoplast between intracellular AM structures and root cortical cells. Operation of mycorrhiza-inducible P transporters in the AM P uptake pathway appears, at least partially, to replace uptake via different P transporters located in root epidermis and root hairs.
Location: Australia
No related grants have been discovered for Donna Glassop.