Designing a nitrogen-efficient cold-tolerant maize for modern agricultural systems.

Maize (Zea mays L.) is the world's most productive grain crop and a cornerstone of global food supply. However, in temperate agricultural systems, maize exhibits 2 key anomalies.

MdARF2-mediated ABA signaling orchestrates malate biosynthesis and transport via repression of MdcyMDH and MdMATEL1 in apple.

Abscisic acid (ABA) is a crucial regulator of plant growth, while vacuolar malate accumulation is pivotal for determining fruit taste and flavor. However, the relationship between ABA signaling and malate metabolism remains poorly understood. Here, we show that the ABA-modulated auxin response factor 2 (ARF2)-multidrug and toxic compound extrusion protein like 1 (MdMATEL1)/cytosolic NAD-dependent malate dehydrogenase (MdcyMDH) network regulates malate accumulation in apple fruit.

Plant Membrane-On-A-Chip: A Platform for Studying Plant Membrane Proteins and Lipids.

The cell plasma membrane is a two-dimensional, fluid mosaic material composed of lipids and proteins that create a semipermeable barrier defining the cell from its environment. Compared with soluble proteins, the methodologies for the structural and functional characterization of membrane proteins are challenging. An emerging tool for studies of membrane proteins in mammalian systems is a "plasma membrane on a chip," also known as a supported lipid bilayer.

Alternative Splicing Underpins the ALMT9 Transporter Function for Vacuolar Malic Acid Accumulation in Apple.

Vacuolar malic acid accumulation largely determines fruit acidity, a key trait for the taste and flavor of apple and other fleshy fruits. Aluminum-activated malate transporter 9 (ALMT9/Ma1) underlies a major genetic locus, Ma, for fruit acidity in apple, but how the protein transports malate across the tonoplast is unclear. Here, it is shown that overexpression of the coding sequence of Ma1 (Ma1α) drastically decreases fruit acidity in "Royal Gala" apple, leading to uncovering alternative splicing underpins Ma1's function.

Identifying genes associated with abiotic stress tolerance suitable for CRISPR/Cas9 editing in upland rice cultivars adapted to acid soils.

Five genes of large phenotypic effect known to confer abiotic stress tolerance in rice were selected to characterize allelic variation in commercial Colombian upland rice cultivars adapted to drought-prone acid soil environments (cv. Llanura11 and Porvenir12). Allelic variants of the genes , , , , and were characterized by PCR and/or Sanger sequencing in the two upland cultivars and compared with the Nipponbare and other reference genomes.

Plant HKT Channels: An Updated View on Structure, Function and Gene Regulation.

HKT channels are a plant protein family involved in sodium (Na) and potassium (K) uptake and Na-K homeostasis. Some HKTs underlie salt tolerance responses in plants, while others provide a mechanism to cope with short-term K shortage by allowing increased Na uptake under K starvation conditions. HKT channels present a functionally versatile family divided into two classes, mainly based on a sequence polymorphism found in the sequences underlying the selectivity filter of the first pore loop.

Indole-3-glycerolphosphate synthase, a branchpoint for the biosynthesis of tryptophan, indole, and benzoxazinoids in maize.

The maize (Zea mays) genome encodes three indole-3-glycerolphosphate synthase enzymes (IGPS1, 2, and 3) catalyzing the conversion of 1-(2-carboxyphenylamino)-l-deoxyribulose-5-phosphate to indole-3-glycerolphosphate. Three further maize enzymes (BX1, benzoxazinoneless 1; TSA, tryptophan synthase alpha subunit; and IGL, indole glycerolphosphate lyase) convert indole-3-glycerolphosphate to indole, which is released as a volatile defense signaling compound and also serves as a precursor for the biosynthesis of tryptophan and defense-related benzoxazinoids. Phylogenetic analyses showed that IGPS2 is similar to enzymes found in both monocots and dicots, whereas maize IGPS1 and IGPS3 are in monocot-specific clades.

Low Additive Genetic Variation in a Trait Under Selection in Domesticated Rice.

Quantitative traits are important targets of both natural and artificial selection. The genetic architecture of these traits and its change during the adaptive process is thus of fundamental interest. The fate of the additive effects of variants underlying a trait receives particular attention because they constitute the genetic variation component that is transferred from parents to offspring and thus governs the response to selection.

A Sugar Transporter Takes Up both Hexose and Sucrose for Sorbitol-Modulated In Vitro Pollen Tube Growth in Apple.

Rapid pollen tube growth requires uptake of Suc or its hydrolytic products, hexoses, from the apoplast of surrounding tissues in the style. Due to species-specific sugar requirements, reliance of pollen germination and tube growth on cell wall invertase and Suc or hexose transporters varies between species, but it is not known if plants have a sugar transporter that mediates the uptake of both hexose and Suc for pollen tube growth. Here, we show that a sugar transporter protein in apple (), MdSTP13a, takes up both hexose and Suc when expressed in yeast, and is essential for pollen tube growth on Glc and Suc but not on maltose.

Apple ALMT9 Requires a Conserved C-Terminal Domain for Malate Transport Underlying Fruit Acidity.

Malate accumulation in the vacuole largely determines apple () fruit acidity, and low fruit acidity is strongly associated with truncation of , an ortholog of () in Arabidopsis (). A mutation at base 1,455 in the open reading frame of leads to a premature stop codon that truncates the protein by 84 amino acids at its C-terminal end. Here, we report that both the full-length protein, Ma1, and its naturally occurring truncated protein, ma1, localize to the tonoplast; when expressed in oocytes and cells, Ma1 mediates a malate-dependent inward-rectifying current, whereas the ma1-mediated transmembrane current is much weaker, indicating that ma1 has significantly lower malate transport activity than Ma1.

Signal coordination before, during and after stomatal closure in response to drought stress.

Signal coordination in response to changes in water availability remains unclear, as does the role of embolism events in signaling drought stress. Sunflowers were exposed to two drought treatments of varying intensity while simultaneously monitoring changes in stomatal conductance, acoustic emissions (AE), turgor pressure, surface-level electrical potential, organ-level water potential and leaf abscisic acid (ABA) concentration. Leaf, stem and root xylem vulnerability to embolism were measured with the single vessel injection technique.

Emerging Pleiotropic Mechanisms Underlying Aluminum Resistance and Phosphorus Acquisition on Acidic Soils.

Aluminum (Al) toxicity on acidic soils significantly damages plant roots and inhibits root growth. Hence, crops intoxicated by Al become more sensitive to drought stress and mineral nutrient deficiencies, particularly phosphorus (P) deficiency, which is highly unavailable on tropical soils. Advances in our understanding of the physiological and genetic mechanisms that govern plant Al resistance have led to the identification of Al resistance genes, both in model systems and in crop species.

Two citrate transporters coordinately regulate citrate secretion from rice bean root tip under aluminum stress.

Aluminum (Al)-induced organic acid secretion from the root apex is an important Al resistance mechanism. However, it remains unclear how plants fine-tune root organic acid secretion which can contribute significantly to the loss of fixed carbon from the plant. Here, we demonstrate that Al-induced citrate secretion from the rice bean root apex is biphasic, consisting of an early phase with low secretion and a later phase of large citrate secretion.

() contributes to natural variation in aluminum resistance in diverse genetic backgrounds of rice ().

Transcription factors (TFs) regulate the expression of other genes to indirectly mediate stress resistance mechanisms. Therefore, when studying TF-mediated stress resistance, it is important to understand how TFs interact with genes in the genetic background. Here, we fine-mapped the aluminum (Al) resistance QTL to a 44-kb region containing six genes.

An Arabidopsis ABC Transporter Mediates Phosphate Deficiency-Induced Remodeling of Root Architecture by Modulating Iron Homeostasis in Roots.

The remodeling of root architecture is a major developmental response of plants to phosphate (Pi) deficiency and is thought to enhance a plant's ability to forage for the available Pi in topsoil. The underlying mechanism controlling this response, however, is poorly understood. In this study, we identified an Arabidopsis mutant, hps10 (hypersensitive to Pi starvation 10), which is morphologically normal under Pi sufficient condition but shows increased inhibition of primary root growth and enhanced production of lateral roots under Pi deficiency.

The ALMT Family of Organic Acid Transporters in Plants and Their Involvement in Detoxification and Nutrient Security.

About a decade ago, members of a new protein family of anion channels were discovered on the basis of their ability to confer on plants the tolerance toward toxic aluminum ions in the soil. The efflux of Al-chelating malate anions through these channels is stimulated by external Al ions. This feature of a few proteins determined the name of the entire protein family as Aluminum-activated Malate Transporters (ALMT).

The Raf-like Kinase ILK1 and the High Affinity K+ Transporter HAK5 Are Required for Innate Immunity and Abiotic Stress Response.

Plant perception of pathogen-associated molecular patterns (PAMPs) and other environmental stresses trigger transient ion fluxes at the plasma membrane. Apart from the role of Ca(2+) uptake in signaling, the regulation and significance of PAMP-induced ion fluxes in immunity remain unknown. We characterized the functions of INTEGRIN-LINKED KINASE1 (ILK1) that encodes a Raf-like MAP2K kinase with functions insufficiently understood in plants.

Evolving technologies for growing, imaging and analyzing 3D root system architecture of crop plants.

A plant's ability to maintain or improve its yield under limiting conditions, such as nutrient deficiency or drought, can be strongly influenced by root system architecture (RSA), the three-dimensional distribution of the different root types in the soil. The ability to image, track and quantify these root system attributes in a dynamic fashion is a useful tool in assessing desirable genetic and physiological root traits. Recent advances in imaging technology and phenotyping software have resulted in substantive progress in describing and quantifying RSA.

Plant Adaptation to Acid Soils: The Molecular Basis for Crop Aluminum Resistance.

Aluminum (Al) toxicity in acid soils is a significant limitation to crop production worldwide, as approximately 50% of the world's potentially arable soil is acidic. Because acid soils are such an important constraint to agriculture, understanding the mechanisms and genes conferring resistance to Al toxicity has been a focus of intense research interest in the decade since the last article on crop acid soil tolerance was published in this journal. An impressive amount of progress has been made during that time that has greatly increased our understanding of the diversity of Al resistance genes and mechanisms, how resistance gene expression is regulated and triggered by Al and Al-induced signals, and how the proteins encoded by these genes function and are regulated.

The role of aluminum sensing and signaling in plant aluminum resistance.

As researchers have gained a better understanding in recent years into the physiological, molecular, and genetic basis of how plants deal with aluminum (Al) toxicity in acid soils prevalent in the tropics and sub-tropics, it has become clear that an important component of these responses is the triggering and regulation of cellular pathways and processes by Al. In this review of plant Al signaling, we begin by summarizing the understanding of physiological mechanisms of Al resistance, which first led researchers to realize that Al stress induces gene expression and modifies protein function during the activation of Al resistance responses. Subsequently, an overview of Al resistance genes and their function provides verification that Al induction of gene expression plays a major role in Al resistance in many plant species.

Phosphate transporters OsPHT1;9 and OsPHT1;10 are involved in phosphate uptake in rice.

We characterized the function of two rice phosphate (Pi) transporters: OsPHT1;9 (OsPT9) and OsPHT1;10 (OsPT10). OsPT9 and OsPT10 were expressed in the root epidermis, root hairs and lateral roots, with their expression being specifically induced by Pi starvation. In leaves, expression of the two genes was observed in both mesophyll and vasculature.