Hydrogen‐ion Concentration of Leaf Juice in Relation to Environment and Plant Species

Hurd-Karrer, Annie M.

doi:10.1002/j.1537-2197.1939.tb09365.x

Cited by 13 publications

(1 citation statement)

References 29 publications

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“…The vacuolar sap of plant cells is typically acidic on account of its substantial content of hydroxycarboxylic acids, and there are some well‐known examples of extreme acid accumulation in C 3 plants – such as oxalic acid in leaves of Begonia , Oxalis and sorrel ( Rumex acetosa ), and citric acid in Citrus fruits – that can result in vacuolar pH values as low as 2 (Bennet‐Clark, 1933 ; Hurd‐Karrer, 1939 ). But in most plants the vacuolar carboxylate anions are largely charge‐balanced by the strong inorganic cations K + , Na + , Ca 2+ and Mg 2+ , with the result that the vacuolar contents are only mildly acidic, with free H + concentrations in the micromolar range (pH 5–6).…”

Section: Do C 3 Plants Accumulate Organic Acids At...mentioning

confidence: 99%

CAM photosynthesis: the acid test

Winter

Smith

2021

New Phytologist

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There is currently considerable interest in the prospects for bioengineering crassulacean acid metabolism (CAM) photosynthesisor key elements associated with it, such as increased water-use efficiencyinto C 3 plants. Resolving how CAM photosynthesis evolved from the ancestral C 3 pathway could provide valuable insights into the targets for such bioengineering efforts. It has been proposed that the ability to accumulate organic acids at night may be common among C 3 plants, and that the transition to CAM might simply require enhancement of pre-existing fluxes, without the need for changes in circadian or diurnal regulation. We show, in a survey encompassing 40 families of vascular plants, that nocturnal acidification is a feature entirely restricted to CAM species. Although many C 3 species can synthesize malate during the light period, we argue that the switch to night-time malic acid accumulation requires a fundamental metabolic reprogramming that couples glycolytic breakdown of storage carbohydrate to the process of net dark CO 2 fixation. This central element of the CAM pathway, even when expressed at a low level, represents a biochemical capability not seen in C 3 plants, and so is better regarded as a discrete evolutionary innovation than as part of a metabolic continuum between C 3 and CAM.

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Section: Do C 3 Plants Accumulate Organic Acids At...mentioning

confidence: 99%