ALEXANDER JOHNSON

Metabolic engineering of bread wheat improves grain iron concentration and bioavailability

Publisher: Wiley

Date: 25-01-2019

DOI: 10.1111/PBI.13074

Crops for a future climate

Publisher: CSIRO Publishing

Date: 2013

DOI: 10.1071/FPV40N2_FO

Abstract: The papers in this special issue were mainly derived from sessions at the International Botanical Congress in July 2011 in Melbourne, and at the ComBio meeting in Cairns, September 2011. They make contributions towards one of the most burning issues we face today: increasing sustainable crop production to provide sufficient high quality food to feed an ever increasing global human population, all in the face of climate change. Plant and crop science will have a major part in ensuring that agricultural production can meet these multiple demands. Contributions in this volume go beyond raising issues and highlighting potential effects of climate change factors, but also point out ways to better adapt to the inevitable.

Plant regeneration through indirect organogenesis and genetic transformation of Eucalyptus polybractea R.T. Baker

Publisher: Elsevier BV

Date: 08-2016

DOI: 10.1016/J.INDCROP.2016.03.025

Constitutive overexpression of the OsNAS gene family reveals single-gene strategies for effective iron- and zinc-biofortification of rice endosperm

Publisher: Public Library of Science (PLoS)

Date: 06-09-2011

DOI: 10.1371/JOURNAL.PONE.0024476

CRISPR-Cas systems: ushering in the new genome editing era

Publisher: Informa UK Limited

Date: 2018

DOI: 10.1080/21655979.2018.1470720

Biofortified indica rice attains iron and zinc nutrition dietary targets in the field

Publisher: Springer Science and Business Media LLC

Date: 25-01-2016

DOI: 10.1038/SREP19792

Abstract: More than two billion people are micronutrient deficient. Polished grains of popular rice varieties have concentration of approximately 2 μg g −1 iron (Fe) and 16 μg g −1 zinc (Zn). The HarvestPlus breeding programs for biofortified rice target 13 μg g −1 Fe and 28 μg g −1 Zn to reach approximately 30% of the estimated average requirement (EAR). Reports on engineering Fe content in rice have shown an increase up to 18 μg g −1 in glasshouse settings in contrast, under field conditions, 4 μg g −1 was the highest reported concentration. Here, we report on selected transgenic events, field evaluated in two countries, showing 15 μg g −1 Fe and 45.7 μg g −1 Zn in polished grain. Rigorous selection was applied to 1,689 IR64 transgenic events for insert cleanliness and, trait and agronomic performances. Event NASFer-274 containing rice nicotianamine synthase ( OsNAS2 ) and soybean ferritin ( SferH-1 ) genes showed a single locus insertion without a yield penalty or altered grain quality. Endosperm Fe and Zn enrichment was visualized by X-ray fluorescence imaging. The Caco-2 cell assay indicated that Fe is bioavailable. No harmful heavy metals were detected in the grain. The trait remained stable in different genotype backgrounds.

Genome-wide identification and characterization of the GDP-L-galactose phosphorylase gene family in bread wheat

Publisher: Springer Science and Business Media LLC

Date: 26-11-2019

DOI: 10.1186/S12870-019-2123-1

Abstract: Ascorbate is a powerful antioxidant in plants and an essential micronutrient for humans. The GDP-L-galactose phosphorylase ( GGP ) gene encodes the rate-limiting enzyme of the L-galactose pathway—the dominant ascorbate biosynthetic pathway in plants—and is a promising gene candidate for increasing ascorbate in crops. In addition to transcriptional regulation, GGP production is regulated at the translational level through an upstream open reading frame (uORF) in the long 5′-untranslated region (5’UTR). The GGP genes have yet to be identified in bread wheat ( Triticum aestivum L.), one of the most important food grain sources for humans. Bread wheat chromosomal groups 4 and 5 were found to each contain three homoeologous TaGGP genes on the A, B, and D subgenomes ( TaGGP2-A / B / D and TaGGP1-A / B/D , respectively) and a highly conserved uORF was present in the long 5’UTR of all six genes. Phylogenetic analyses demonstrated that the TaGGP genes separate into two distinct groups and identified a duplication event of the GGP gene in the ancestor of the Brachypodium /Triticeae lineage. A microsynteny analysis revealed that the TaGGP1 and TaGGP2 subchromosomal regions have no shared synteny suggesting that TaGGP2 may have been duplicated via a transposable element. The two groups of TaGGP genes have distinct expression patterns with the TaGGP1 homoeologs broadly expressed across different tissues and developmental stages and the TaGGP2 homoeologs highly expressed in anthers. Transient transformation of the TaGGP coding sequences in Nicotiana benthamiana leaf tissue increased ascorbate concentrations more than five-fold, confirming their functional role in ascorbate biosynthesis in planta . We have identified six TaGGP genes in the bread wheat genome, each with a highly conserved uORF. Phylogenetic and microsynteny analyses highlight that a transposable element may have been responsible for the duplication and specialized expression of GGP2 in anthers in the Brachypodium /Triticeae lineage. Transient transformation of the TaGGP coding sequences in N. benthamiana demonstrated their activity in planta . The six TaGGP genes and uORFs identified in this study provide a valuable genetic resource for increasing ascorbate concentrations in bread wheat.

Localization of iron in rice grain using synchrotron X-ray fluorescence microscopy and high resolution secondary ion mass spectrometry

Publisher: Elsevier BV

Date: 03-2014

DOI: 10.1016/J.JCS.2013.12.006

Hyperaccumulation of zinc by Noccaea caerulescens results in a cascade of stress responses and changes in the elemental profile

Publisher: Oxford University Press (OUP)

Date: 2014

DOI: 10.1039/C4MT00132J

Abstract: Noccaea caerulescens can accumulate more than 2% Zn in the leaves without showing any outwards signs of toxicity however a myriad of elemental and metabolite changes occur at these concentrations.

Spatial control of transgene expression in rice (Oryza sativa L.) using the GAL4 enhancer trapping system

Publisher: Wiley

Date: 02-02-2005

DOI: 10.1111/J.1365-313X.2005.02339.X

Identification of a Stelar-Localized Transport Protein That Facilitates Root-to-Shoot Transfer of Chloride in Arabidopsis

Publisher: Oxford University Press (OUP)

Date: 11-12-2015

DOI: 10.1104/PP.15.01163

Root-Specific Transcript Profiling of Contrasting Rice Genotypes in Response to Salinity Stress

Publisher: Elsevier BV

Date: 2011

DOI: 10.1093/MP/SSQ056

Abstract: Elevated salinity imposes osmotic and ion toxicity stresses on living cells and requires a multitude of responses in order to enable plant survival. Building on earlier work profiling transcript levels in rice (Oryza sativa) shoots of FL478, a salt-tolerant indica recombinant inbred line, and IR29, a salt-sensitive cultivar, transcript levels were compared in roots of these two accessions as well as in the roots of two additional salt-tolerant indica genotypes, the landrace Pokkali and the recombinant inbred line IR63731. The aim of this study was to compare transcripts in the sensitive and the tolerant lines in order to identify genes likely to be involved in plant salinity tolerance, rather than in responses to salinity per se. Transcript profiles of several gene families with known links to salinity tolerance are described (e.g. HKTs, NHXs). The putative function of a set of genes identified through their salt responsiveness, transcript levels, and/or chromosomal location (i.e. underneath QTLs for salinity tolerance) is also discussed. Finally, the parental origin of the Saltol region in FL478 is further investigated. Overall, the dataset presented appears to be robust and it seems likely that this system could provide a reliable strategy for the discovery of novel genes involved in salinity tolerance.

Plant Growth Promotion and Heat Stress Amelioration in Arabidopsis Inoculated with Paraburkholderia phytofirmans PsJN Rhizobacteria Quantified with the GrowScreen-Agar II Phenotyping Platform

Publisher: MDPI AG

Date: 30-10-2022

DOI: 10.3390/PLANTS11212927

Abstract: High temperatures inhibit plant growth. A proposed strategy for improving plant productivity under elevated temperatures is the use of plant growth-promoting rhizobacteria (PGPR). While the effects of PGPR on plant shoots have been extensively explored, roots—particularly their spatial and temporal dynamics—have been hard to study, due to their below-ground nature. Here, we characterized the time- and tissue-specific morphological changes in bacterized plants using a novel non-invasive high-resolution plant phenotyping and imaging platform—GrowScreen-Agar II. The platform uses custom-made agar plates, which allow air exchange to occur with the agar medium and enable the shoot to grow outside the compartment. The platform provides light protection to the roots, the exposure of it to the shoots, and the non-invasive phenotyping of both organs. Arabidopsis thaliana, co-cultivated with Paraburkholderia phytofirmans PsJN at elevated and ambient temperatures, showed increased lengths, growth rates, and numbers of roots. However, the magnitude and direction of the growth promotion varied depending on root type, timing, and temperature. The root length and distribution per depth and according to time was also influenced by bacterization and the temperature. The shoot biomass increased at the later stages under ambient temperature in the bacterized plants. The study offers insights into the timing of the tissue-specific, PsJN-induced morphological changes and should facilitate future molecular and biochemical studies on plant–microbe–environment interactions.

Investigation of a His‐rich arabinogalactan‐protein for micronutrient biofortification of cereal grain

Publisher: Wiley

Date: 25-07-2011

DOI: 10.1111/J.1399-3054.2011.01499.X

Abstract: The micronutrient content of most cereal grains is low and responsible for malnutrition deficiencies in millions of people who rely on grains as their primary food source. Any strategy that can increase the micronutrient content of grain will have significant benefits to world health. We identified a gene from barley encoding a cell wall protein with multiple histidine (His)-rich motifs interspersed with short arabinogalactan-protein (AGP) domains and have called it Hordeum vulgare His-rich AGP (HvHRA1). Sequence analysis shows that His-rich AGPs are rare in plants and that the number of His-rich and AGP domains differ between cereals and dicots. The barley and wheat encoded proteins have more than 13 His-rich domains, whereas the putative rice orthologue has only 5 His-rich regions. His-rich motifs are well-established metal-binding motifs therefore, we developed transgenic (Tx) rice plants that constitutively overexpress barley HvHRA1. There was no significant effect on plant growth or grain yield in Tx plants. Purification of AGPs from wild-type and Tx plants showed that only Tx plants contained detectable levels of a His-rich AGP. Calcein assay shows that the AGP fraction from Tx plants had increased binding affinity for Cu(2+) . Micronutrient analysis of brown and white rice showed that the grain nutrient yield for Fe, Zn and Cu was higher in two Tx lines compared to their respective nulls, although the differences were not statistically significant. This approach highlights the potential of the plant apoplast (cell wall) for storage of key nutrients through overexpression of genes for metal-binding proteins.

Laterally resolved speciation of arsenic in roots of wheat and rice using fluorescence‐XANES imaging

Publisher: Wiley

Date: 11-11-2013

DOI: 10.1111/NPH.12595

Abstract: Accumulation of arsenic (As) within plant tissues represents a human health risk, but there remains much to learn regarding the speciation of As within plants. We developed synchrotron‐based fluorescence‐X‐ray absorption near‐edge spectroscopy (fluorescence‐ XANES ) imaging in hydrated and fresh plant tissues to provide laterally resolved data on the in situ speciation of As in roots of wheat ( Triticum aestivum ) and rice ( Oryza sativa ) exposed to 2 μM As(V) or As( III ). When exposed to As(V), the As was rapidly reduced to As( III ) within the root, with As(V) calculated to be present only in the rhizodermis. However, no uncomplexed As( III ) was detected in any root tissues, because of the efficient formation of the As( III )–thiol complex – this As species was calculated to account for all of the As in the cortex and stele. The observation that uncomplexed As( III ) was below the detection limit in all root tissues explains why the transport of As to the shoots is low, given that uncomplexed As( III ) is the major As species transported within the xylem and phloem. Using fluorescence‐ XANES imaging, we have provided in situ data showing the accumulation and transformation of As within hydrated and fresh root tissues.

Linkage Projects - Grant ID: LP130100785

Start Date: 01-2014

End Date: 12-2017

Amount: $429,369.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0770966

Start Date: 2007

End Date: 12-2009

Amount: $420,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE230100107

Start Date: 2023

End Date: 06-2024

Amount: $1,042,177.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0883746

Start Date: 03-2009

End Date: 12-2012

Amount: $85,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP190100631

Start Date: 11-2020

End Date: 11-2025

Amount: $860,774.00

Funder: Australian Research Council