Heterodimerization of Arabidopsis calcium/proton exchangers contributes to regulation of guard cell dynamics and plant defense responses.

Arabidopsis thaliana cation exchangers (CAX1 and CAX3) are closely related tonoplast-localized calcium/proton (Ca2+/H+) antiporters that contribute to cellular Ca2+ homeostasis. CAX1 and CAX3 were previously shown to interact in yeast; however, the function of this complex in plants has remained elusive. Here, we demonstrate that expression of CAX1 and CAX3 occurs in guard cells.

The sodium transporter encoded by the HKT1;2 gene modulates sodium/potassium homeostasis in tomato shoots under salinity.

Excessive soil salinity diminishes crop yield and quality. In a previous study in tomato, we identified two closely linked genes encoding HKT1-like transporters, HKT1;1 and HKT1;2, as candidate genes for a major quantitative trait locus (kc7.1) related to shoot Na /K homeostasis - a major salt tolerance trait - using two populations of recombinant inbred lines (RILs).

Molecular identification and functional analysis of a maize (Zea mays) DUR3 homolog that transports urea with high affinity.

Successful molecular cloning and functional characterization of a high-affinity urea permease ZmDUR3 provide convincing evidence of ZmDUR3 roles in root urea acquisition and internal urea-N-remobilization of maize plants. Urea occurs ubiquitously in both soils and plants. Being a major form of nitrogen fertilizer, large applications of urea assist cereals in approaching their genetic yield potential, but due to the low nitrogen-use efficiency of crops, this practice poses a severe threat to the environment through their hypertrophication.

Protocol: a fast and simple in situ PCR method for localising gene expression in plant tissue.

Background: An important step in characterising the function of a gene is identifying the cells in which it is expressed. Traditional methods to determine this include in situ hybridisation, gene promoter-reporter fusions or cell isolation/purification techniques followed by quantitative PCR. These methods, although frequently used, can have limitations including their time-consuming nature, limited specificity, reliance upon well-annotated promoters, high cost, and the need for specialized equipment.

The Na(+) transporter, TaHKT1;5-D, limits shoot Na(+) accumulation in bread wheat.

Bread wheat (Triticum aestivum L.) has a major salt tolerance locus, Kna1, responsible for the maintenance of a high cytosolic K(+) /Na(+) ratio in the leaves of salt stressed plants. The Kna1 locus encompasses a large DNA fragment, the distal 14% of chromosome 4DL.

Rapid shoot-to-root signalling regulates root hydraulic conductance via aquaporins.

We investigated how root hydraulic conductance (normalized to root dry weight, Lo ) is regulated by the shoot. Shoot topping (about 30% reduction in leaf area) reduced Lo of grapevine (Vitis vinifera L.), soybean (Glycine max L.

Protocol: optimising hydroponic growth systems for nutritional and physiological analysis of Arabidopsis thaliana and other plants.

Background: Hydroponic growth systems are a convenient platform for studying whole plant physiology. However, we found through trialling systems as they are described in the literature that our experiments were frequently confounded by factors that affected plant growth, including algal contamination and hypoxia. We also found the way in which the plants were grown made them poorly amenable to a number of common physiological assays.

Transcriptomics on small samples.

Interrogating the cell-specific transcriptome forms an important component of understanding the role that specific cells play in assisting a plant to overcome abiotic stress. Among the challenges arising when extracting RNA from individual plant cells are: the isolation of pure cell populations; the small yield of material when isolating specific cell types, and ensuring an accurate representation of the transcriptome from each cell type after amplification of RNA. Here we describe two approaches for isolating RNA from specific cell types-single cell sampling and analysis (SiCSA) and laser capture microdissection.

Wheat grain yield on saline soils is improved by an ancestral Na⁺ transporter gene.

The ability of wheat to maintain a low sodium concentration ([Na(+)]) in leaves correlates with improved growth under saline conditions. This trait, termed Na(+) exclusion, contributes to the greater salt tolerance of bread wheat relative to durum wheat. To improve the salt tolerance of durum wheat, we explored natural diversity in shoot Na(+) exclusion within ancestral wheat germplasm.

Cell-specific compartmentation of mineral nutrients is an essential mechanism for optimal plant productivity--another role for TPC1?

Vacuoles of different leaf cell-types vary in their capacity to store specific mineral elements. In Arabidopsis thaliana potassium (K) accumulates preferentially in epidermal and bundle sheath cells whereas calcium (Ca) and magnesium (Mg) are stored at high concentrations only in mesophyll cells. Accumulation of these elements in a particular vacuole can be reciprocal, i.

Cell-specific vacuolar calcium storage mediated by CAX1 regulates apoplastic calcium concentration, gas exchange, and plant productivity in Arabidopsis.

The physiological role and mechanism of nutrient storage within vacuoles of specific cell types is poorly understood. Transcript profiles from Arabidopsis thaliana leaf cells differing in calcium concentration ([Ca], epidermis <10 mM versus mesophyll >60 mM) were compared using a microarray screen and single-cell quantitative PCR. Three tonoplast-localized Ca(2+) transporters, CAX1 (Ca(2+)/H(+)-antiporter), ACA4, and ACA11 (Ca(2+)-ATPases), were identified as preferentially expressed in Ca-rich mesophyll.