Fine-tuning gibberellin improves rice alkali-thermal tolerance and yield.

Soil alkalinization and global warming are predicted to pose major challenges to agriculture in the future, as they continue to accelerate, markedly reducing global arable land and crop yields. Therefore, strategies for future agriculture are needed to further improve globally cultivated, relatively high-yielding Green Revolution varieties (GRVs) derived from the SEMIDWARF 1 (SD1) gene. Here we propose that precise regulation of the phytohormone gibberellin (GA) to optimal levels is the key to not only confer alkali-thermal tolerance to GRVs, but also to further enhance their yield.

The molecular basis of heat stress responses in plants.

Global warming impacts crop production and threatens food security. Elevated temperatures are sensed by different cell components. Temperature increases are classified as either mild warm temperatures or excessively hot temperatures, which are perceived by distinct signaling pathways in plants.

ORP2A mediates ER-autophagosomal membrane contact sites and regulates PI3P in plant autophagy.

Autophagy is an intracellular degradation system for cytoplasmic constituents which is mediated by the formation of a double-membrane organelle termed the autophagosome and its subsequent fusion with the lysosome/vacuole. The formation of the autophagosome requires membrane from the endoplasmic reticulum (ER) and is tightly regulated by a series of autophagy-related (ATG) proteins and lipids. However, how the ER contacts autophagosomes and regulates autophagy remain elusive in plants.

VAMP724 and VAMP726 are involved in autophagosome formation in .

Macroautophagy/autophagy, an evolutionarily conserved degradative process essential for cell homeostasis and development in eukaryotes, involves autophagosome formation and fusion with a lysosome/vacuole. The soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins play important roles in regulating autophagy in mammals and yeast, but relatively little is known about SNARE function in plant autophagy. Here we identified and characterized two SNAREs, AT4G15780/VAMP724 and AT1G04760/VAMP726, involved in plant autophagy.

A genetic module at one locus in rice protects chloroplasts to enhance thermotolerance.

How the plasma membrane senses external heat-stress signals to communicate with chloroplasts to orchestrate thermotolerance remains elusive. We identified a quantitative trait locus, (), consisting of two genes, and , that interact together to enhance rice thermotolerance and reduce grain-yield losses caused by heat stress. Upon heat stress, plasma membrane-localized E3 ligase TT3.

A unique AtSar1D-AtRabD2a nexus modulates autophagosome biogenesis in .

In eukaryotes, secretory proteins traffic from the endoplasmic reticulum (ER) to the Golgi apparatus via coat protein complex II (COPII) vesicles. Intriguingly, during nutrient starvation, the COPII machinery acts constructively as a membrane source for autophagosomes during autophagy to maintain cellular homeostasis by recycling intermediate metabolites. In higher plants, essential roles of autophagy have been implicated in plant development and stress responses.

Plant Rho GTPase signaling promotes autophagy.

The roles of Rho family guanosine triphosphatases (GTPases) of plants (ROPs) in modulating plant growth and development have been well characterized. However, little is known about the roles of ROP signaling pathways in regulating plant autophagy and autophagosome formation. In this study, we identify a unique ROP signaling mechanism, which mediates developmental to autophagic transition under stress conditions in the model plant Arabidopsis.

MYB117 is a negative regulator of flowering time in .

Plant flowering is crucial for the onset and progression of reproduction processes. The control of flowering time is a sophisticated system with multiple known regulatory mechanisms in plants. Here, we show that MYB117 participates in the flowering time regulation in as mutants exhibited early flowering phenotypes under long-day condition.

MYB106 is a negative regulator and a substrate for CRL3 E3 ligase in regulating flowering time in Arabidopsis thaliana.

Flowering time is crucial for successful reproduction in plants, the onset and progression of which are strictly controlled. However, flowering time is a complex and environmentally responsive history trait and the underlying mechanisms still need to be fully characterized. Post-translational regulation of the activities of transcription factors (TFs) is a dynamic and essential mechanism for plant growth and development.

Transient Expression of Fluorescent Fusion Proteins in Arabidopsis Protoplasts.

Transient expression using protoplasts isolated from Arabidopsis suspension culture cells is a fast and useful tool for analyzing protein subcellular localization and dynamics in plant cells. Recently, super-resolution imaging techniques such as N-SIM (Nikon, Structured Illumination Microscopy) are widely used in cell biology study, allowing cell biologists to obtain unattainable details and relationships of cell structures and functions by conventional confocal imaging. To facilitate the usage of protoplasts transient expression and super-resolution imaging for protein localization and dynamic analysis in plant cell biology research, here we describe updated protocols of protoplasts isolation from Arabidopsis suspension culture cells and transient expression assay for protein trafficking and localization study.

New insights into AtNBR1 as a selective autophagy cargo receptor in Arabidopsis.

Selective autophagy, mediated by cargo receptors and recruiting specific targets to autophagosomes for degradation and recycling, plays an important role in quality control and cellular homeostasis in eukaryotes. The Arabidopsis AtNBR1 shares a similar domain organization with the mammalian autophagic receptors p62 and NBR1. We recently demonstrated that AtNBR1 functions as a selective autophagy receptor for the exocyst component AtExo70E2, a marker for the Exocyst-positive organelle (EXPO), which was achieved via a specific ATG8-AtNBR1-AtExo70E2 interaction in Arabidopsis.

AtNBR1 Is a Selective Autophagic Receptor for AtExo70E2 in Arabidopsis.

Selective autophagy is a subcellular process whereby cytoplasmic materials are selectively sequestered into autophagosomes for subsequent delivery to the vacuole for degradation and recycling. Arabidopsis () NBR1 (next to BRCA1 gene 1 protein; AtNBR1) has been proposed to function as a selective autophagy receptor in plants, whereby AtNBR1 anchors the ubiquitinated targets to autophagosomes for degradation. However, the specific cargos of AtNBR1 remain elusive.

The interplay between endomembranes and autophagy in plants.

Autophagosomes are unique double-membrane organelles that enclose a portion of intracellular components for lysosome/vacuole delivery to maintain cellular homeostasis in eukaryotic cells. Genetic screening has revealed the requirement of autophagy-related proteins for autophagosome formation, although the origin of the autophagosome membrane remains elusive. The endomembrane system is a series of membranous organelles maintained by dynamic membrane flow between various compartments.

Exocyst-Positive Organelles and Autophagosomes Are Distinct Organelles in Plants.

Autophagosomes are organelles that deliver cytosolic proteins for degradation in the vacuole of the cell. In contrast, exocyst-positive organelles (EXPO) deliver cytosolic proteins to the cell surface and therefore represent a form of unconventional protein secretion. Because both structures have two boundary membranes, it has been suggested that they may have been falsely treated as separate entities.

A two-locus interaction causes interspecific hybrid weakness in rice.

Reproductive barriers perform a vital role during speciation. Hybrid weakness, the poorer development of hybrids compared with their parents, hinders gene exchange between different species at the postzygotic stage. Here we show that two incompatible dominant loci (Hwi1 and Hwi2) involving three genes are likely to determine the high temperature-dependent expression of hybrid weakness in interspecific hybrids of rice.

An in vivo expression system for the identification of cargo proteins of vacuolar sorting receptors in Arabidopsis culture cells.

Vacuolar sorting receptors (VSRs) are type I integral membrane family proteins that in plant cells are thought to recognize cargo proteins at the late Golgi or trans-Golgi network (TGN) for vacuolar transport via the pre-vacuolar compartment (PVC). However, little is known about VSR cargo proteins in plants. Here we developed and tested an in vivo expression system for the identification of VSR cargos which is based on the premise that the expressed N-terminus of VSRs will be secreted into the culture medium along with their corresponding cargo proteins.

The novel quantitative trait locus GL3.1 controls rice grain size and yield by regulating Cyclin-T1;3.

Increased crop yields are required to support rapid population growth worldwide. Grain weight is a key component of rice yield, but the underlying molecular mechanisms that control it remain elusive. Here, we report the cloning and characterization of a new quantitative trait locus (QTL) for the control of rice grain length, weight and yield.