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Item Open Access Repurposed inhibitor of bacterial dihydrodipicolinate reductase exhibits effective herbicidal activity(Springer Nature, 2023) Mackie, E.R.R.; Barrow, A.S.; Giel, M.-C.; Hulett, M.D.; Gendall, A.R.; Panjikar, S.; Soares da Costa, T.P.Herbicide resistance represents one of the biggest threats to our natural environment and agricultural sector. Thus, new herbicides are urgently needed to tackle the rise in herbicide-resistant weeds. Here, we employed a novel strategy to repurpose a 'failed' antibiotic into a new and target-specific herbicidal compound. Specifically, we identified an inhibitor of bacterial dihydrodipicolinate reductase (DHDPR), an enzyme involved in lysine biosynthesis in plants and bacteria, that exhibited no antibacterial activity but severely attenuated germination of the plant Arabidopsis thaliana. We confirmed that the inhibitor targets plant DHDPR orthologues in vitro, and exhibits no toxic effects against human cell lines. A series of analogues were then synthesised with improved efficacy in germination assays and against soil-grown A. thaliana. We also showed that our lead compound is the first lysine biosynthesis inhibitor with activity against both monocotyledonous and dicotyledonous weed species, by demonstrating its effectiveness at reducing the germination and growth of Lolium rigidum (rigid ryegrass) and Raphanus raphanistrum (wild radish). These results provide proof-of-concept that DHDPR inhibition may represent a much-needed new herbicide mode of action. Furthermore, this study exemplifies the untapped potential of repurposing 'failed' antibiotic scaffolds to fast-track the development of herbicide candidates targeting the respective plant enzymes.Item Open Access A feedback loop between the androgen receptor and 6-phosphogluoconate dehydrogenase (6PGD) drives prostate cancer growth(eLife Sciences Publications, 2021) Gillis, J.L.; Hinneh, J.A.; Ryan, N.K.; Irani, S.; Moldovan, M.; Quek, L.-E.; Shrestha, R.; Hanson, A.R.; Xie, J.; Hoy, A.J.; Holst, J.; Centenera, M.M.; Mills, I.G.; Lynn, D.J.; Selth, L.A.; Butler, L.M.Alterations to the androgen receptor (AR) signalling axis and cellular metabolism are hallmarks of prostate cancer. This study provides insight into both hallmarks by uncovering a novel link between AR and the pentose phosphate pathway (PPP). Specifically, we identify 6-phosphogluoconate dehydrogenase (6PGD) as an androgen-regulated gene that is upregulated in prostate cancer. AR increased the expression of 6PGD indirectly via activation of sterol regulatory element binding protein 1 (SREBP1). Accordingly, loss of 6PGD, AR or SREBP1 resulted in suppression of PPP activity as revealed by 1,2-13C2 glucose metabolic flux analysis. Knockdown of 6PGD also impaired growth and elicited death of prostate cancer cells, at least in part due to increased oxidative stress. We investigated the therapeutic potential of targeting 6PGD using two specific inhibitors, physcion and S3, and observed substantial anti-cancer activity in multiple models of prostate cancer, including aggressive, therapy-resistant models of castration-resistant disease as well as prospectively collected patient-derived tumour explants. Targeting of 6PGD was associated with two important tumour-suppressive mechanisms: first, increased activity of the AMP-activated protein kinase (AMPK), which repressed anabolic growth-promoting pathways regulated by acetyl-CoA carboxylase 1 (ACC1) and mammalian target of rapamycin complex 1 (mTORC1); and second, enhanced AR ubiquitylation, associated with a reduction in AR protein levels and activity. Supporting the biological relevance of positive feedback between AR and 6PGD, pharmacological co-targeting of both factors was more effective in suppressing the growth of prostate cancer cells than single-agent therapies. Collectively, this work provides new insight into the dysregulated metabolism of prostate cancer and provides impetus for further investigation of co-targeting AR and the PPP as a novel therapeutic strategy.Item Metadata only Cell Wall Responses to Biotrophic Fungal Pathogen Invasion(Wiley, 2019) Chowdhury, J.; Coad, B.; Little, A.To a plant the surrounding environment is filled with microbial organisms looking to take advantage of the bountiful resources held within. In order for a pathogen to access the internal nutrients it must gain entry through the plant cell outer layers that consist of the cuticular wax and the plant cell wall. This barrier is a complex structure composed of diverse waxes, lipids, polysaccharides, proteins, lignin, and antimicrobial compounds and plays many crucial roles during plant defence, growth, and development. We now have more evidence than ever about the dynamic nature of the cell wall providing various interaction-dependent passive and active defence responses, hence justifying a necessity of evolving such a complex structure. Here we summarise the current understanding of this multi-layered defence system, using the biotrophic interaction between barley and the causal agent of powdery mildew, Blumeria graminis f. sp. hordei (Bgh).Item Open Access Spectral reflectance indices as proxies for yield potential and heat stress tolerance in spring wheat: Heritability estimates and marker-trait associations(Higher Education Press, 2019) Liu, C.; Pinto, F.; Cossani, C.M.; Sukumaran, S.; Reynolds, M.P.The application of spectral reflectance indices (SRIs) as proxies to screen for yield potential (YP) and heat stress (HS) is emerging in crop breeding programs. Thus, a comparison of SRIs and their associations with grain yield (GY) under YP and HS conditions is important. In this study, we assessed the usefulness of 27 SRIs for indirect selection for agronomic traits by evaluating an elite spring wheat association mapping initiative (WAMI) population comprising 287 elite lines under YP and HS conditions. Genetic and phenotypic analysis identified 11 and 9 SRIs in different developmental stages as efficient indirect selection indices for yield in YP and HS conditions, respectively. We identified enhanced vegetation index (EVI) as the common SRI associated with GY under YP at booting, heading and late heading stages, whereas photochemical reflectance index (PRI) and normalized difference vegetation index (NDVI) were the common SRIs under booting and heading stages in HS. Genomewide association study (GWAS) using 18704 single nucleotide polymorphisms (SNPs) from Illumina iSelect 90K identified 280 and 43 marker-trait associations for efficient SRIs at different developmental stages under YP and HS, respectively. Common genomic regions for multiple SRIs were identified in 14 regions in 9 chromosomes: 1B (60–62 cM), 3A (15, 85–90, 101– 105 cM), 3B (132–134 cM), 4A (47–51 cM), 4B (71– 75 cM), 5A (43–49, 56–60, 89–93 cM), 5B (124–125 cM), 6A (80–85 cM), and 6B (57–59, 71 cM). Among them, SNPs in chromosome 5A (89–93 cM) and 6A (80–85 cM) were co-located for yield and yield related traits. Overall, this study highlights the utility of SRIs as proxies for GY under YP and HS. High heritability estimates and identification of marker-trait associations indicate that SRIs are useful tools for understanding the genetic basis of agronomic and physiological traits.Item Open Access The Timing of Application and Inclusion of a Surfactant Are Important for Absorption and Translocation of Foliar Phosphoric Acid by Wheat Leaves(Frontiers Media S.A., 2019) Peirce, C.A.E.; McBeath, T.M.; Priest, C.; McLaughlin, M.J.Introduction: Foliar applied phosphorus (P) has the potential to provide a more tactical approach to P fertilization that could enhance P use efficiency. The aims of this study were to investigate the influence of adjuvant choice and application timing of foliar applied phosphoric acid on leaf wettability, foliar uptake, translocation, and grain yield of wheat plants. Materials and Methods: We measured the contact angles of water and fertilizers on wheat leaves, and the uptake, translocation and wheat yield response to isotopicallylabelled phosphoric acid in combination with five different adjuvants when foliar-applied to wheat at either early tillering or flag leaf emergence. Results: There was high foliar uptake of phosphoric acid in combination with all adjuvants that contained a surfactant, but only one treatment resulted in a 12% increase in grain yield and two treatments resulted in a decrease in grain yield. Despite the wettability of all foliar fertilizers being markedly different, foliar uptake was similar for all treatments that contained a surfactant. The translocation of phosphorus from foliar sources was higher when applied at a later growth stage than when applied at tillering despite the leaf surface properties that affect wettability being similar across all leaves at both growth stages. Discussion: Both the timing of foliar application and the inclusion of a surfactant in the formulation are important for absorption and translocation of phosphoric acid by wheat leaves, however high foliar uptake and translocation will not always translate to a yield increase.Item Metadata only In reply to: 'towards precision regional anesthesia: is the PENG block appropriate for all hip fracture surgeries?'(BMJ Publishing Group, 2022) Lin, D.-Y.; Morrison, C.; Brown, B.; Saies, A.; Pawar, R.; Vermeulen, M.; Anderson, S.R.; Lee, T.S.; Doornberg, J.; Kroon, H.; Jaarsma, R.Item Open Access The GABA shunt contributes to ROS homeostasis in guard cells of Arabidopsis(Wiley, 2024) Xu, B.; Feng, X.; Piechatzek, A.; Zhang, S.; Konrad, K.R.; Kromdijk, J.; Hedrich, R.; Gilliham, M.γ-Aminobutyric acid (GABA) accumulates rapidly under stress via the GABA shunt pathway, which has been implicated in reducing the accumulation of stress-induced reactive oxygen species (ROS) in plants. γ-Aminobutyric acid has been demonstrated to act as a guard-cell signal in Arabidopsis thaliana, modulating stomatal opening. Knockout of the major GABA synthesis enzyme Glutamate Decarboxylase 2 (GAD2) increases the aperture of gad2 mutants, which results in greater stomatal conductance and reduces water-use efficiency compared with wild-type plants. Here, we found that the additional loss of GAD1, GAD4, and GAD5 in gad2 leaves increased GABA deficiency but abolished the more open stomatal pore phenotype of gad2, which we link to increased cytosolic calcium (Ca2+ ) and ROS accumulation in gad1/2/4/5 guard cells. Compared with wild-type and gad2 plants, glutamate was ineffective in closing gad1/2/4/5 stomatal pores, whereas lowering apoplastic calcium, applying ROS inhibitors or complementation with GAD2 reduced gad1/2/4/5 guard-cell ROS, restored the gad2-like greater stomatal apertures of gad1/2/4/5 beyond that of wild-type. We conclude that GADs are important contributors to ROS homeostasis in guard cells likely via a Ca2+ -mediated pathway. As such, this study reveals greater complexity in GABA's role as a guard-cell signal and the interactions it has with other established signals.Item Metadata only Urban soil health: A city-wide survey of chemical and biological properties of urban agriculture soils(Elsevier, 2020) Salomon, M.J.; Watts-Williams, S.J.; McLaughlin, M.J.; Cavagnaro, T.R.Abstract not availableItem Metadata only Understanding Preferences for Dietary Supplements and Fortified Food during Pregnancy: A Discrete Choice Experiment(Taylor and Francis, 2019) Malek, L.; Umberger, W.J.; Zhou, S.J.; Makrides, M.; Huynh, E.Using a discrete choice experiment, we examine pregnant women’s preferences to determine the relative importance they place on product attributes when choosing between nutritionally fortified food and beverage products, and supplement tablets. The choice experiment was included in a cross-sectional web-based questionnaire completed by 857 pregnant Australian women. Latent class analysis identified four distinct consumer segments: ‘Nulliparous information seekers’ (42% of sample), ‘Lower-income milk-lovers’ (22%), ‘Older multiparous tablet users’ (16%), and ‘Young juice-lovers’ (20%). While nutrient levels were a strong driver of choice in the largest segment, over one-third of pregnant women were not influenced by levels of recommended nutrients (folate or iodine) in supplement products. Pregnancy supplements endorsed by a reputable government science agency were most appealing in three of the segments. The information gained regarding product preferences of different consumer segments can aid in targeting pregnant women and those planning pregnancy with more appropriate nutrition information, advice, and products.Item Metadata only Boosting Triticeae crop grain yield by manipulating molecular modules to regulate inflorescence architecture: insights and knowledge from other cereal crops(Oxford University Press (OUP), 2024) Zhang, Y.; Shen, C.; Shi, J.; Shi, J.; Zhang, D.; Melzer, R.One of the challenges for global food security is to reliably and sustainably improve the grain yield of cereal crops. One solution is to modify the architecture of the grain-bearing inflorescence to optimize for grain number and size. Cereal inflorescences are complex structures, with determinacy, branching patterns, and spikelet/floret growth patterns that vary by species. Recent decades have witnessed rapid advancements in our understanding of the genetic regulation of inflorescence architecture in rice, maize, wheat, and barley. Here, we summarize current knowledge on key genetic factors underlying the different inflorescence morphologies of these crops and model plants (Arabidopsis and tomato), focusing particularly on the regulation of inflorescence meristem determinacy and spikelet meristem identity and determinacy. We also discuss strategies to identify and utilize these superior alleles to optimize inflorescence architecture and, ultimately, improve crop grain yield.Item Open Access How do brassinosteroids fit in bud outgrowth models?(Oxford University Press (OUP), 2024) Kelly, J.H.; Brewer, P.B.; Byrne, M.Short stature crops were developed during the green revolution mainly due to their resistance to falling over (lodging), improved crop harvestability and management, and a greater proportion of biomass in the grains, leading to superior yield. These crops were disrupted in the gibberellin (GA) pathway, which caused the reduced height (Gao and Chu, 2020). GA disruption can introduce unwanted effects in other important traits such as fertility, leaf expansion, seed quality, and stress response (Gao and Chu, 2020). Hence, there are currently efforts to uncouple negative side effects of GA-related short stature or utilize alternative dwarfing pathways, such as brassinosteroids (BRs).Item Open Access Barley Nodulin 26-like intrinsic protein permeates water, metalloids, saccharides, and ion pairs due to structural plasticity and diversification(Elsevier, 2023) Venkataraghavan, A.; Schwerdt, J.G.; Tyerman, S.D.; Hrmova, M.Aquaporins can facilitate the passive movement of water, small polar molecules and some ions. Here, we examined solute selectivity for the barley Nodulin 26-like Intrinsic Protein (HvNIP2;1) embedded in liposomes and examined through stopped-flow light scattering spectrophotometry and Xenopus laevis oocyte swelling assays. We found that HvNIP2;1 permeates water, boric and germanic acids, sucrose, and lactose but not d-glucose or d-fructose. Other saccharides, such as neutral (d-mannose, d-galactose, d-xylose, d-mannoheptaose) and charged (N-acetyl d-glucosamine, d-glucosamine, d-glucuronic acid) aldoses, disaccharides (cellobiose, gentiobiose, trehalose), trisaccharide raffinose, and urea, glycerol, and acyclic polyols were permeated to a much lower extent. We observed apparent permeation of hydrated KCl and MgSO4 ions, while CH3COONa and NaNO3 permeated at significantly lower rates. Our experiments with boric acid and sucrose revealed no apparent interaction between solutes when permeated together, and AgNO3 or H[AuCl4] blocked the permeation of all solutes. Docking of sucrose in HvNIP2;1 and spinach water-selective SoPIP2;1 aquaporins revealed the structural basis for sucrose permeation in HvNIP2;1 but not in SoPIP2;1, and defined key residues interacting with this permeant. In a biological context, sucrose transport could constitute a novel element of plant saccharide-transporting machinery. Phylogenomic analyses of 164 Viridiplantae and 2,993 Archaean, bacterial, fungal, and Metazoan aquaporins rationalized solute poly-selectivity in NIP3 sub-clade entries and suggested that they diversified from other sub-clades to acquire a unique specificity of saccharide transporters. Solute specificity definition in NIP aquaporins could inspire developing plants for food production.Item Metadata only The role of plant vasculature in tackling N₂O emissions(Elsevier (Cell Press), 2023) Safdar, L.B.; Fisk, I.D.; Foulkes, M.J.Rising demand for protein-rich foods can impact N₂O emissions from croplands. Recent research has pointed to the role of modified plant vasculature in grain protein increase. Here we highlight how discovering the mechanistic role of plant vasculature in protein improvement and nitrogen-use efficiency could reduce global N₂O emissions.Item Open Access Sodium doping and trapped ion mobility spectrometry improve lipid detection for novel MALDI-MSI analysis of oats(Elsevier BV, 2024) Lau, W.C.D.; Donnellan, L.; Briggs, M.; Rupasinghe, T.; Harris, J.C.; Hayes, J.E.; Hoffmann, P.Oat (Avena sativa L.) is an important cereal grain with a unique nutritional profile including a high proportion of lipids. Understanding lipid composition and distribution in oats is valuable for plant, food and nutritional research, and can be achieved using MALDI mass spectrometry imaging (MALDI-MSI). However, this approach presents several challenges for sample preparation (hardness of grains) and analysis (isobaric and isomeric properties of lipids). Here, oat sections were successfully mounted onto gelatin-coated indium tin oxide slides with minimal tearing. Poor detection of triacylglycerols was resolved by applying sodium chloride during mounting, increasing signal intensity. In combination with trapped ion mobility spectrometry (TIMS), lipid identification significantly improved, and we report the separation of several isobaric and isomeric lipids with visualisation of their “true” spatial distributions. This study describes a novel MALDI-TIMS-MSI analytical technique for oat lipids, which may be used to improve the discovery of biomarkers for grain quality.Item Open Access Arbuscular-Mycorrhizal Symbiosis in Medicago Regulated by the Transcription Factor MtbHLHm1;1 and the Ammonium Facilitator Protein MtAMF1;3(MDPI AG, 2023) Ovchinnikova, E.; Chiasson, D.; Wen, Z.; Wu, Y.; Tahaei, H.; Smith, P.M.C.; Perrine-Walker, F.; Kaiser, B.N.Root systems of most land plants are colonised by arbuscular mycorrhiza fungi. The symbiosis supports nutrient acquisition strategies predominantly associated with plant access to inorganic phosphate. The nutrient acquisition is enhanced through an extensive network of external fungal hyphae that extends out into the soil, together with the development of fungal structures forming specialised interfaces with root cortical cells. Orthologs of the bHLHm1;1 transcription factor, previously described in soybean nodules (GmbHLHm1) and linked to the ammonium facilitator protein GmAMF1;3, have been identified in Medicago (Medicago truncatula) roots colonised by AM fungi. Expression studies indicate that transcripts of both genes are also present in arbuscular containing root cortical cells and that the MtbHLHm1;1 shows affinity to the promoter of MtAMF1;3. Both genes are induced by AM colonisation. Loss of Mtbhlhm1;1 expression disrupts AM arbuscule abundance and the expression of the ammonium transporter MtAMF1;3. Disruption of Mtamf1;3 expression reduces both AM colonisation and arbuscule development. The respective activities of MtbHLHm1;1 and MtAMF1;3 highlight the conservation of putative ammonium regulators supporting both the rhizobial and AM fungal symbiosis in legumes.Item Open Access Predictors of compliance with higher dose omega-3 fatty acid supplementation during pregnancy and implications for the risk of prematurity: exploratory analysis of the ORIP randomised trial(BMJ Journals, 2023) Sullivan, T.R.; Yelland, L.N.; Gibson, R.A.; Thakkar, S.K.; Huang, F.; Best, K.P.; Devaraj, S.; Zolezzi, I.S.; Makrides, M.Background: Intention-to-treat analyses of the Omega‐3 to Reduce the Incidence of Prematurity (ORIP) trial found that omega-3 (n-3) fatty acid supplementation reduces the risk of prematurity in the subgroup of women with a singleton pregnancy and low n-3 status early in pregnancy, but not overall. However, results may have been influenced by less-than-optimal compliance. Objectives: To identify predictors of compliance with n-3 supplementation and determine treatment effects among compliers. Design: Exploratory analyses of a multicentre-blinded randomised trial. Setting: 6 tertiary care centres in Australia. Participants: 5328 singleton pregnancies. Interventions: Daily capsules containing 900 mg n-3 long-chain polyunsaturated fatty acids or vegetable oil, consumed from before 20 weeks gestation until 34 weeks gestation. Outcome measures: Early preterm (<34 weeks gestation) and preterm birth (<37 weeks gestation). Women were considered compliant if they reported missing less than a third of their allocated capsules in the previous week during a mid-pregnancy appointment. Results: Among 2654 singleton pregnancies in the n-3 intervention group, 1727 (65%) were deemed compliant with supplementation. Maternal characteristics associated with compliance included age, years of full-time education, consuming alcohol but not smoking in the 3 months leading up to pregnancy, fewer previous births and taking dietary supplements at enrolment. Based on complier average causal effects, n-3 supplementation reduced the risk of preterm birth in compliers (relative risk=0.76; 95% CI 0.60 to 0.97), but not early preterm birth (relative risk=0.80; 95% CI 0.44 to 1.46). Consistent with intention-to-treat analyses, the lack of an overall effect on early preterm birth in compliers appeared to be due to beneficial effects in women with low n-3 status at enrolment but not women with replete status. Conclusions: Results in compliers were similar to those from intention-to-treat analyses, suggesting that non-compliance was not a major factor in explaining outcomes from the ORIP trial. Trial registration number: ACTRN12613001142729.Item Open Access Challenges facing sustainable protein production: Opportunities for cereals(Elsevier, 2023) Safdar, L.B.; Foulkes, M.J.; Kleiner, F.H.; Searle, I.R.; Bhosale, R.A.; Fisk, I.D.; Boden, S.A.Rising demands for protein across the world are likely to increase livestock production, as meat provides ∼40% of dietary protein. This will come at significant environmental expense; therefore, a shift towards plant-based protein sources would provide major benefits. While legumes provide substantial plant-based proteins, cereals are the major constituents of global foods with wheat alone accounting for 15-20% of the required protein intake. Improving protein content in wheat is limited by phenotyping challenges, lack of genetic potential of modern germplasms, negative yield trade-off, and the environmental cost of nitrogen fertilisers. Presenting wheat as a case study, we discuss how increasing protein content in cereals through a revised breeding strategy combined with robust phenotyping can ensure a sustainable protein supply while minimising the environmental impact of nitrogen fertiliser.Item Open Access Selected adjuvants increase the efficacy of foliar biofortification of iodine in bread wheat (Triticum aestivum L.) grain(Frontiers Media SA, 2023) Magor, E.; Wilson, M.D.; Wong, H.; Cresswell, T.; Sánchez-Palacios, J.T.; Bell, R.W.; Penrose, B.Agronomic biofortification of crops is a promising approach that can improve the nutritional value of staple foods by alleviating dietary micronutrient deficiencies. Iodine deficiency is prevalent in many countries, including Australia, but it is not clear what foliar application strategies will be effective for iodine fortification of grain. This study hypothesised that combining adjuvants with iodine in foliar sprays would improve iodine penetration in wheat, leading to more efficient biofortification of grains. The glasshouse experiment included a total of nine treatments, including three reference controls: 1) Water; 2) potassium iodate (KIO3) and 3) potassium chloride (KCl); and a series of six different non-ionic surfactant or oil-based adjuvants: 4) KIO3 + BS1000; 5) KIO3 + Pulse® Penetrant; 6) KIO3 + Uptake®; 7) KIO3 + Hot-Up®; 8) KIO3 + Hasten® and 9) KIO3 + Synerterol® Horti Oil. Wheat was treated at heading, and again during the early milk growth stage. Adding the organosilicon-based adjuvant (Pulse®) to the spray formulation resulted in a significant increase in grain loading of iodine to 1269 µg/kg compared to the non-adjuvant KIO3 control at 231µg/kg, and the water and KCl controls (both 51µg/kg). The second most effective adjuvant was Synerterol® Horti Oil, which increased grain iodine significantly to 450µg/kg. The Uptake®, BS1000, Hasten®, and Hot-Up® adjuvants did not affect grain iodine concentrations relative to the KIO3 control. Importantly, iodine application and the subsequent increase in grain iodine had no significant effects on biomass production and grain yield relative to the controls. These results indicate that adjuvants can play an important role in agronomic biofortification practices, and organosilicon-based products have a great potential to enhance foliar penetration resulting in a higher translocation rate of foliar-applied iodine to grains, which is required to increase the iodine density of staple grains effectively.Item Open Access Exploring aquaporin functions during changes in leaf water potential(Frontiers Media SA, 2023) Byrt, C.S.; Zhang, R.Y.; Magrath, I.; Chan, K.X.; De Rosa, A.; McGaughey, S.Maintenance of optimal leaf tissue humidity is important for plant productivity and food security. Leaf humidity is influenced by soil and atmospheric water availability, by transpiration and by the coordination of water flux across cell membranes throughout the plant. Flux of water and solutes across plant cell membranes is influenced by the function of aquaporin proteins. Plants have numerous aquaporin proteins required for a multitude of physiological roles in various plant tissues and the membrane flux contribution of each aquaporin can be regulated by changes in protein abundance, gating, localisation, posttranslational modifications, protein:protein interactions and aquaporin stoichiometry. Resolving which aquaporins are candidates for influencing leaf humidity and determining how their regulation impacts changes in leaf cell solute flux and leaf cavity humidity is challenging. This challenge involves resolving the dynamics of the cell membrane aquaporin abundance, aquaporin sub-cellular localisation and location-specific post-translational regulation of aquaporins in membranes of leaf cells during plant responses to changes in water availability and determining the influence of cell signalling on aquaporin permeability to a range of relevant solutes, as well as determining aquaporin influence on cell signalling. Here we review recent developments, current challenges and suggest open opportunities for assessing the role of aquaporins in leaf substomatal cavity humidity regulation.Item Open Access Water use dynamics of dryland wheat grown under elevated CO₂ with supplemental nitrogen(CSIRO Publishing, 2024) Uddin, S.; Parvin, S.; Armstrong, R.; Fitzgerald, G.J.; Löw, M.; Houshmandfar, A.; Tavakkoli, E.; Tausz-Posch, S.; O'Leary, G.J.; Tausz, M.; Fukai, S.Context. Elevated atmospheric CO2 (e[CO2]) and nitrogen (N) fertilisation stimulate biomass and yield of crops. However, their interactions depend on crop growth stages and may affect water use dynamics. Aims and methods. This study investigated the interactive effects of two N rates, 0 and 100 kg N ha−1 , and two CO2 concentrations, ambient (a[CO2], ~400 μmol mol−1 ) and e[CO2] (~550 μmol mol−1 ), on biomass, yield and water use of two wheat cultivars, Wyalkatchem (N-use efficient) and Yitpi (local), using a free air CO2 enrichment facility. Key results. Elevated [CO2] stimulated leaf area (10%, P = 0.003) and aboveground biomass (11%, P = 0.03). In addition, e[CO2] reduced stomatal conductance (25%, P < 0.001) and increased net assimilation rates (12%, P < 0.001), resulting in greater (40%, P < 0.001) intrinsic water use efficiency. During early growth stages, e[CO2]resulted in higher water use than a[CO2]; however, this difference disappeared laterin the season, resulting in similar cumulative water use under both CO2 concentrations. Supplemental N stimulated grain yield of Yitpi by 14% while decreasing that of Wyalkatchem by 7% (N × cultivar, P = 0.063). With supplemental N, Yitpi maintained greater post-anthesis leaf N, chlorophyll content, canopy cover and net assimilation rate than Wyalkatchem. Conclusions. During early growth stages, the e[CO2]-induced stimulation of leaf-level water use efficiency was offset by greater biomass, resulting in higher water use. By the end of the season, similar cumulative water use under both CO2 concentrations indicates the dominating effect of the prevailing seasonal conditions in the study area. Observed yield responses of the studied cultivarsto supplemental N were associated with their ability to maintain post-anthesis photosynthetic capabilities. Implications. Our findings suggest that N-use efficiency traits and responsiveness need to be considered independently to optimise benefits from the ‘CO2 fertilisation effect’ through breeding.