BIG coordinates auxin and SHORT ROOT to promote asymmetric stem cell divisions in Arabidopsis roots.

BIG regulates ground tissue formative divisions by bridging the auxin gradient with SHR abundance in Arabidopsis roots. The formative divisions of cortex/endodermis initials (CEIs) and CEI daughter cells (CEIDs) in Arabidopsis roots are coordinately controlled by the longitudinal auxin gradient and the radial SHORT ROOT (SHR) abundance. However, the mechanism underlying this coordination remains poorly understood.

The OsDIR55 gene increases salt tolerance by altering the root diffusion barrier.

The increased soil salinity is becoming a major challenge to produce more crops and feed the growing population of the world. In this study, we demonstrated that overexpression of OsDIR55 gene enhances rice salt tolerance by altering the root diffusion barrier. OsDIR55 is broadly expressed in all examined tissues and organs with the maximum expression levels at lignified regions in rice roots.

COBL7 is required for stomatal formation via regulation of cellulose deposition in Arabidopsis.

As a key regulator of plant photosynthesis, water use efficiency and immunity, stomata are specialized cellular structures that adopt defined shapes. However, our knowledge about the genetic players of stomatal pore formation and stomatal morphogenesis remains limited. Forward genetic screening, positional cloning, confocal and electron microscopy, physiological and pharmacological assays were employed for isolation and characterization of mutants and genes.

Genome-Wide Identification and Expression Pattern Analysis of Dirigent Members in the Genus .

Dirigent (DIR) members have been shown to play essential roles in plant growth, development and adaptation to environmental changes. However, to date, there has been no systematic analysis of the DIR members in the genus . Here, 420 genes were identified from nine rice species to have the conserved DIR domain.

OsαCA1 Affects Photosynthesis, Yield Potential, and Water Use Efficiency in Rice.

Plant growth and crop yield are essentially determined by photosynthesis when considering carbon dioxide (CO) availability. CO diffusion inside a leaf is one of the factors that dictate the CO concentrations in chloroplasts. Carbonic anhydrases (CAs) are zinc-containing enzymes that interconvert CO and bicarbonate ions (HCO), which, consequently, affect CO diffusion and thus play a fundamental role in all photosynthetic organisms.

The Arabidopsis Rab protein RABC1 affects stomatal development by regulating lipid droplet dynamics.

Lipid droplets (LDs) are evolutionarily conserved organelles that serve as hubs of cellular lipid and energy metabolism in virtually all organisms. Mobilization of LDs is important in light-induced stomatal opening. However, whether and how LDs are involved in stomatal development remains unknown.

BIG Modulates Stem Cell Niche and Meristem Development via SCR/SHR Pathway in Arabidopsis Roots.

BIG, a regulator of polar auxin transport, is necessary to regulate the growth and development of Arabidopsis. Although mutations in the gene cause severe root developmental defects, the exact mechanism remains unclear. Here, we report that disruption of the gene resulted in decreased quiescent center (QC) activity and columella cell numbers, which was accompanied by the downregulation of () gene expression.

OsCPL3 is involved in brassinosteroid signaling by regulating OsGSK2 stability.

Glycogen synthase kinase 3 (GSK3) proteins play key roles in brassinosteroid (BR) signaling during plant growth and development by phosphorylating various substrates. However, how GSK3 protein stability and activity are themselves modulated is not well understood. Here, we demonstrate in vitro and in vivo that C-TERMINAL DOMAIN PHOSPHATASE-LIKE 3 (OsCPL3), a member of the RNA Pol II CTD phosphatase-like family, physically interacts with OsGSK2 in rice (Oryza sativa).

Countering elevated CO induced Fe and Zn reduction in Arabidopsis seeds.

Growth at increased concentrations of CO induces a reduction in seed zinc (Zn) and iron (Fe). Using Arabidopsis thaliana, we investigated whether this could be mitigated by reducing the elevated CO -induced decrease in transpiration. We used an infrared imaging-based screen to isolate mutants in At1g08080 that encodes ALPHA CARBONIC ANHYDRASE 7 (ACA7).

COBL9 and COBL7 synergistically regulate root hair tip growth via controlling apical cellulose deposition.

Root hairs are cylindrical extensions of root epidermal cells that are important for the acquisition of water and minerals, interactions between plant and microbes. The deposition of cell wall materials in the tip enables root hairs to maintain elongation constantly. To date, our knowledge of the regulators that connect the architecture of cell wall and the root hair development remains very limited.

OsBC1L1 and OsBC1L8 function in stomatal development in rice.

Stomata that are bordered by pairs of guard cells are specialized for regulating gas exchange and transpiration in plants. The stomatal morphology of grass is unique, characterized by two dumbbell-shaped guard cells flanked by two lateral subsidiary cells. This morphology and developmental pattern enable grass stomata to respond to environmental signals efficiently.

Stomatal responses to carbon dioxide and light require abscisic acid catabolism in .

In plants, stomata control water loss and CO uptake. The aperture and density of stomatal pores, and hence the exchange of gases between the plant and the atmosphere, are controlled by internal factors such as the plant hormone abscisic acid (ABA) and external signals including light and CO. In this study, we examine the importance of ABA catabolism in the stomatal responses to CO and light.

RIN13-mediated disease resistance depends on the SNC1-EDS1/PAD4 signaling pathway in Arabidopsis.

Plants have evolved an innate immune system to protect themselves from pathogen invasion with the help of intracellular nucleotide-binding leucine-rich repeat (NLR) receptors, though the mechanisms remain largely undefined. RIN13 (RPM1-interacting protein 13) was previously reported to enhance disease resistance, and suppress RPM1 (a CNL-type NLR)-mediated hypersensitive response in Arabidopsis via an as yet unknown mechanism. Here, we show that RIN13 is a nuclear-localized protein, and functions therein.

ROS of Distinct Sources and Salicylic Acid Separate Elevated CO-Mediated Stomatal Movements in Arabidopsis.

Elevated CO (eCO) often reduces leaf stomatal aperture and density thus impacts plant physiology and productivity. We have previously demonstrated that the Arabidopsis BIG protein distinguishes between the processes of eCO-induced stomatal closure and eCO-inhibited stomatal opening. However, the mechanistic basis of this action is not fully understood.

BIG regulates sugar response and C/N balance in Arabidopsis.

Mutations in gene not only produce pleiotropic phenotypes of plant development but also impair plant adaptive responses under various stresses. However, the role of gene in sugar signaling is not known. In this study, we first found that deficiency significantly sensitized the sugar-induced anthocyanin accumulation and the sugar-inhibited primary root growth, suggesting BIG is an important component of the sugar signaling pathway.

Homologous genes of epidermal patterning factor regulate stomatal development in rice.

Stomata are microscopic pores on the surface of leaves through which water as vapor passes to the atmosphere and CO uptake for the photosynthesis. The signaling peptides of the epidermal patterning factor (EPF) family regulate stomatal development and density in Arabidopsis. Several putative homologs of EPF/EPFL exist in rice genome.

Rice BIG gene is required for seedling viability.

Arabidopsis BIG (AtBIG) gene encodes an enormous protein that is required for auxin transport. Loss of AtBIG function not only profoundly changes plant architecture but also alters plant adaptability to environmental stimuli. A putative homolog of AtBIG exists in the rice genome, but no function has been ascribed to it.

BIG regulates stomatal immunity and jasmonate production in Arabidopsis.

Plants have evolved an array of responses that provide them with protection from attack by microorganisms and other predators. Many of these mechanisms depend upon interactions between the plant hormones jasmonate (JA) and ethylene (ET). However, the molecular basis of these interactions is insufficiently understood.

The BIG protein distinguishes the process of CO -induced stomatal closure from the inhibition of stomatal opening by CO.

We conducted an infrared thermal imaging-based genetic screen to identify Arabidopsis mutants displaying aberrant stomatal behavior in response to elevated concentrations of CO . This approach resulted in the isolation of a novel allele of the Arabidopsis BIG locus (At3g02260) that we have called CO insensitive 1 (cis1). BIG mutants are compromised in elevated CO -induced stomatal closure and bicarbonate activation of S-type anion channel currents.

Sphingosine kinase AtSPHK1 functions in fumonisin B1-triggered cell death in Arabidopsis.

The fungal toxin Fumonisin B1 (FB1) is a strong inducer to trigger plant hypersensitive responses (HR) along with increased long chain bases (LCB) and long chain base phosphates (LCBP) contents, though the regulatory mechanism of FB1 action and how the LCB/LCBP signalling cassette functions during the process is still not fully understood. Here, we report sphingosine kinase 1 (SPHK1) as a key factor in FB1-induced HR by modulating the salicylic acid (SA) pathway and reactive oxygen species (ROS) accumulation in Arabidopsis thaliana. Overexpression of SPHK1 increases the FB1-induced accumulations of ROS and SA.

Long-chain bases and their phosphorylated derivatives differentially regulate cryptogein-induced production of reactive oxygen species in tobacco (Nicotiana tabacum) BY-2 cells.

The proteinaceous elicitor cryptogein triggers defence reactions in Nicotiana tabacum (tobacco) through a signalling cascade, including the early production of reactive oxygen species (ROS) by the plasma membrane (PM)-located tobacco respiratory burst oxidase homologue D (NtRbohD). Sphingolipid long-chain bases (LCBs) are emerging as potent positive regulators of plant defence-related mechanisms. This led us to question whether both LCBs and their phosphorylated derivatives (LCB-Ps) are involved in the early signalling process triggered by cryptogein in tobacco BY-2 cells.

Long-chain base phosphates modulate pollen tube growth via channel-mediated influx of calcium.

Long-chain base phosphates (LCBPs) have been correlated with amounts of crucial biological processes ranging from cell proliferation to apoptosis in animals. However, their functions in plants remain largely unknown. Here, we report that LCBPs, sphingosine-1-phosphate (S1P) and phytosphingosine-1-phosphate (Phyto-S1P), modulate pollen tube growth in a concentration-dependent bi-phasic manner.

Cell wall composition contributes to the control of transpiration efficiency in Arabidopsis thaliana.

To identify loci in Arabidopsis involved in the control of transpirational water loss and transpiration efficiency (TE) we carried out an infrared thermal imaging-based screen. We report the identification of a new allele of the Arabidopsis CesA7 cellulose synthase locus designated AtCesA7(irx3-5) involved in the control of TE. Leaves of the AtCesA7(irx3-5) mutant are warmer than the wild type (WT).

Involvement of sphingosine kinase in plant cell signalling.

In mammalian cells sphingosine-1-phosphate (S1P) is a well-established messenger molecule that participates in a wide range of signalling pathways. The objective of the work reported here was to investigate the extent to which phosphorylated long-chain sphingoid bases, such as sphingosine-1-phosphate and phytosphingosine-1-phosphate (phytoS1P) are used in plant cell signalling. To do this, we manipulated Arabidopsis genes capable of metabolizing these messenger molecules.