AtALMT5 mediates vacuolar fumarate import and regulates the malate/fumarate balance in Arabidopsis.

Malate and fumarate constitute a significant fraction of the carbon fixed by photosynthesis, and they are at the crossroad of central metabolic pathways. In Arabidopsis thaliana, they are transiently stored in the vacuole to keep cytosolic homeostasis. The malate and fumarate transport systems of the vacuolar membrane are key players in the control of cell metabolism.

Vacuolar control of stomatal opening revealed by 3D imaging of the guard cells.

Land plants regulate their photosynthesis and water transpiration by exchanging gases (CO and HO) with the atmosphere. These exchanges take place through microscopic valves, called stomata, on the leaf surface. The opening of the stomata is regulated by two guard cells that actively and reversibly modify their turgor pressure to modulate the opening of the stomatal pores.

Connecting vacuolar and plasma membrane transport networks.

The coordinated control of ion transport across the two major membranes of differentiated plant cells, the plasma and the vacuolar membranes, is fundamental in cell physiology. The stomata responses to the fluctuating environmental conditions are an illustrative example. Indeed, they rely on the coordination of ion fluxes between the different cell compartments.

Dynamic measurement of cytosolic pH and [NO] uncovers the role of the vacuolar transporter AtCLCa in cytosolic pH homeostasis.

Ion transporters are key players of cellular processes. The mechanistic properties of ion transporters have been well elucidated by biophysical methods. Meanwhile, the understanding of their exact functions in cellular homeostasis is limited by the difficulty of monitoring their activity in vivo.

Chloride as a Beneficial Macronutrient in Higher Plants: New Roles and Regulation.

Chloride (Cl) has traditionally been considered a micronutrient largely excluded by plants due to its ubiquity and abundance in nature, its antagonism with nitrate (NO), and its toxicity when accumulated at high concentrations. In recent years, there has been a paradigm shift in this regard since Cl has gone from being considered a harmful ion, accidentally absorbed through NO transporters, to being considered a beneficial macronutrient whose transport is finely regulated by plants. As a beneficial macronutrient, Cl determines increased fresh and dry biomass, greater leaf expansion, increased elongation of leaf and root cells, improved water relations, higher mesophyll diffusion to CO, and better water- and nitrogen-use efficiency.

Chloride as a macronutrient increases water-use efficiency by anatomically driven reduced stomatal conductance and increased mesophyll diffusion to CO.

Chloride (Cl ) has been recently described as a beneficial macronutrient, playing specific roles in promoting plant growth and water-use efficiency (WUE). However, it is still unclear how Cl could be beneficial, especially in comparison with nitrate (NO ), an essential source of nitrogen that shares with Cl similar physical and osmotic properties, as well as common transport mechanisms. In tobacco plants, macronutrient levels of Cl specifically reduce stomatal conductance (g ) without a concomitant reduction in the net photosynthesis rate (A ).

Silent S-Type Anion Channel Subunit SLAH1 Gates SLAH3 Open for Chloride Root-to-Shoot Translocation.

Higher plants take up nutrients via the roots and load them into xylem vessels for translocation to the shoot. After uptake, anions have to be channeled toward the root xylem vessels. Thereby, xylem parenchyma and pericycle cells control the anion composition of the root-shoot xylem sap [1-6].

Chloride regulates leaf cell size and water relations in tobacco plants.

Chloride (Cl(-)) is a micronutrient that accumulates to macronutrient levels since it is normally available in nature and actively taken up by higher plants. Besides a role as an unspecific cell osmoticum, no clear biological roles have been explicitly associated with Cl(-) when accumulated to macronutrient concentrations. To address this question, the glycophyte tobacco (Nicotiana tabacum L.