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7. Contributors

Author

Battle, Martin, primary, Brienen, Roel, additional, Burgess, Alexandra J., additional, Cavanagh, Amanda P., additional, Dall’Osto, Luca, additional, Emmerson, Robyn, additional, Foyer, Christine H., additional, Galbraith, David, additional, Gloor, Emanuel, additional, Gomez, Rodrigo L., additional, Guardini, Zeno, additional, Hanke, Guy, additional, Harbinson, Jeremy, additional, Hofmann, Tanja A., additional, Kaiser, Elias, additional, Kirilovsky, Diana, additional, Krieger-Liszkay, Anja, additional, Lawson, Tracy, additional, McAusland, Lorna, additional, Minagawa, Jun, additional, Morales, Alejandro Sierra, additional, Mullineaux, Conrad W., additional, Murchie, Erik H., additional, Pullin, Jacob, additional, Raines, Christine A., additional, Simkin, Andrew J., additional, van Amerongen, Herbert, additional, Wall, Shellie, additional, and Wientjes, Emilie, additional

Published
2022
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8. Fast stomatal kinetics in sorghum enable tight coordination with photosynthetic responses to dynamic light intensity and safeguard high water use efficiency.

Author

Battle, Martin W, Vialet-Chabrand, Silvere, Kasznicki, Piotr, Simkin, Andrew J, and Lawson, Tracy

Subjects
WATER efficiency, PHOTOSYNTHETIC rates, WATER supply, LIGHT intensity, STOMATA, SORGHUM
Abstract

In this study, we assessed 43 accessions of sorghum from 16 countries across three continents. Our objective was to identify stomatal and photosynthetic traits that could be exploited in breeding programmes to increase photosynthesis without increasing water use under dynamic light environments. Under field conditions, sorghum crops often have limited water availability and are exposed to rapidly fluctuating light intensities, which influences both photosynthesis and stomatal behaviour. Our results highlight a tight coupling between photosynthetic rate (A) and stomatal conductance (g s) even under dynamic light conditions that results in steady intrinsic water use efficiency (W i). This was mainly due to rapid stomatal responses, with the majority of sorghum accessions responding within ≤5 min. The maintenance of the ratio of the concentration of CO2 inside the leaf (C i) and the surrounding atmospheric concentration (C a) over a large range of accessions suggests high stomatal sensitivity to changes in C i, that could underlie the rapid g s responses and extremely close relationship between A and g s under both dynamic and steady-state conditions. Therefore, sorghum represents a prime candidate for uncovering the elusive mechanisms that coordinate A and g s, and such information could be used to design crops with high A without incurring significant water losses and eroding W i. [ABSTRACT FROM AUTHOR]

Published
2024
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12. Chilling or chemical induction of dormancy release in blackcurrant (Ribes nigrum) buds is associated with characteristic shifts in metabolite profiles.

Author

Hancock, Robert D., Schulz, Elisa, Verrall, Susan R., Taylor, June, Méret, Michaël, Brennan, Rex M., Bishop, Gerard J., Else, Mark, Cross, Jerry V., and Simkin, Andrew J.

Subjects
BIOMARKERS, PROTEIN synthesis, HYDROPHILIC compounds, AMINO acids, BUDS
Abstract

This study reveals striking differences in the content and composition of hydrophilic and lipophilic compounds in blackcurrant buds (Ribes nigrum L., cv. Ben Klibreck) resulting from winter chill or chemical dormancy release following treatment with ERGER, a biostimulant used to promote uniform bud break. Buds exposed to high winter chill exhibited widespread shifts in metabolite profiles relative to buds that experience winter chill by growth under plastic. Specifically, extensive chilling resulted in significant reductions in storage lipids and phospholipids, and increases in galactolipids relative to buds that experienced lower chill. Similarly, buds exposed to greater chill exhibited higher levels of many amino acids and dipeptides, and nucleotides and nucleotide phosphates than those exposed to lower chilling hours. Low chill buds (IN) subjected to ERGER treatment exhibited shifts in metabolite profiles similar to those resembling high chill buds that were evident as soon as 3 days after treatment. We hypothesise that chilling induces a metabolic shift which primes bud outgrowth by mobilising lipophilic energy reserves, enhancing phosphate availability by switching from membrane phospholipids to galactolipids and enhancing the availability of free amino acids for de novo protein synthesis by increasing protein turnover. Our results additionally suggest that ERGER acts at least in part by priming metabolism for bud outgrowth. Finally, the metabolic differences presented highlight the potential for developing biochemical markers for dormancy status providing an alternative to time-consuming forcing experiments. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Morphological Changes to Fruit Development Induced by GA 3 Application in Sweet Cherry (Prunus avium L.).

Author

Vignati, Edoardo, Caccamo, Mario, Dunwell, Jim M., and Simkin, Andrew J.

Subjects
FRUIT development, GIBBERELLIC acid, STONE, PISTIL, CELL cycle, SWEET cherry, CHERRIES
Abstract

Cherry (Prunus avium) fruits are important sources of vitamins, minerals, and nutrients in the human diet; however, they contain a large stone, making them inconvenient to eat 'on the move' and process. The exogenous application of gibberellic acid (GA3) can induce parthenocarpy in a variety of fruits during development. Here, we showed that the application of GA3 to sweet cherry unpollinated pistils acted as a trigger for fruit set and permitted the normal formation of fruit up to a period of twenty-eight days, indicating that gibberellins are involved in the activation of the cell cycle in the ovary wall cells, leading to fruit initiation. However, after this period, fruit development ceased and developing fruit began to be excised from the branch by 35 days post treatment. This work also showed that additional signals are required for the continued development of fully mature parthenocarpic fruit in sweet cherry. [ABSTRACT FROM AUTHOR]

Published
2024
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19. Glyceraldehyde-3-phosphate dehydrogenase subunits A and B are essential to maintain photosynthetic efficiency

Author

Simkin, Andrew J., Alqurashi, Mohammed, López-Calcagno, Patricia E., Headland, Lauren R., Raines, Christine, Simkin, Andrew J., Alqurashi, Mohammed, López-Calcagno, Patricia E., Headland, Lauren R., and Raines, Christine

Abstract

In plants, glyceraldehyde-3-phosphate dehydrogenase (GAPDH; EC 1.2.1.12) reversibly converts 1,3-bisphosphoglycerate to glyceraldehyde-3-phosphate coupled with the reduction of NADPH to NADP+. The GAPDH enzyme that functions in the Calvin Benson Cycle is assembled either from four glyceraldehyde-3-phosphate dehydrogenase A subunits (GAPA) proteins forming a homotetramer (A4) or from two GAPA and two glyceraldehyde-3-phosphate dehydrogenase B subunit (GAPB) proteins forming a heterotetramer (A2B2). The relative importance of these two forms of GAPDH in determining the rate of photosynthesis is unknown. To address this question, we measured the photosynthetic rates of Arabidopsis (Arabidopsis thaliana) plants containing reduced amounts of the GAPDH A and B subunits individually and jointly, using T-DNA insertion lines of GAPA and GAPB and transgenic GAPA and GAPB plants with reduced levels of these proteins. Here we show that decreasing the levels of either the A or B subunits decreased the maximum efficiency of CO2 fixation, plant growth, and final biomass. Finally, these data showed that the reduction in GAPA protein to 9% wild-type levels resulted in a 73% decrease in carbon assimilation rates. In contrast, eliminating GAPB protein resulted in a 40% reduction in assimilation rates. This work demonstrates that the GAPA homotetramer can compensate for the loss of GAPB, whereas GAPB alone cannot compensate fully for the loss of the GAPA subunit.

Published
2023

25. Characterization of the plastidial geraniol synthase from Madagascar periwinkle which initiates the monoterpenoid branch of the alkaloid pathway in internal phloem associated parenchyma

Author

Simkin, Andrew J., Miettinen, Karel, Claudel, Patricia, Burlat, Vincent, Guirimand, Grégory, Courdavault, Vincent, Papon, Nicolas, Meyer, Sophie, Godet, Stéphanie, St-Pierre, Benoit, Giglioli-Guivarc’h, Nathalie, Fischer, Marc J.C., Memelink, Johan, and Clastre, Marc

Published
2012
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28. Fruit Development in Sweet Cherry

Author

Vignati, Edoardo, Lipska, Marzena, Dunwell, Jim M, Caccamo, Mario, Simkin, Andrew J., Vignati, Edoardo, Lipska, Marzena, Dunwell, Jim M, Caccamo, Mario, and Simkin, Andrew J.

Abstract

Fruits are an important source of vitamins, minerals and nutrients in the human diet. They also contain several compounds of nutraceutical importance that have significant antioxidant and anti-inflammatory roles, which can protect the consumer from diseases, such as cancer, and cardiovascular disease as well as having roles in reducing the build-up of LDL-cholesterol in blood plasma and generally reduce the risks of disease and age-related decline in health. Cherries contain high concentrations of bioactive compounds and minerals, including calcium, phosphorous, potassium and magnesium, and it is, therefore, unsurprising that cherry consumption has a positive impact on health. This review highlights the development of sweet cherry fruit, the health benefits of cherry consumption, and the options for increasing consumer acceptance and consumption.

Published
2022

29. Chapter 9. Improving carbon fixation

Author

Raines, Christine A., Cavanagh, Amanda, Simkin, Andrew J., Raines, Christine A., Cavanagh, Amanda, and Simkin, Andrew J.

Abstract

The Calvin–Benson (CB) cycle fixes carbon dioxide from the atmosphere into carbon compounds that are then used to make an array of molecules essential for plant growth and development. The efficiency of this cycle is known to be lower than its potential maximum and the goal of improving it has been an objective of plant scientist over the last 20 years. A major limitation to the CB cycle is the first enzyme in the cycle, ribulose 1,5-bisphosphatase, but evidence has also accumulated identifying additional enzymes sedoheptulose 1,7-bisphosphatase and fructose 1,5 bisphosphate aldolase, which share some of this limitation. In this chapter, we review the progress of the work to achieve improvements in CO2 assimilation through improving the function of CB cycle by the (1) engineering of rubisco, (2) introduction of novel pathways or mechanisms to improve the function of rubisco, and (3) direct manipulation of the levels of activity of CB cycle enzymes. Examples are given of successes obtained using these approaches and the limitations of the current approaches and the future prospects are discussed in the context of rising CO2 levels.

Published
2022

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