Starch biosynthesis in guard cells has features of both autotrophic and heterotrophic tissues.

The pathway of starch synthesis in guard cells (GCs), despite the crucial role starch plays in stomatal movements, is not well understood. Here, we characterized starch dynamics in GCs of Arabidopsis (Arabidopsis thaliana) mutants lacking enzymes of the phosphoglucose isomerase-phosphoglucose mutase-ADP-glucose pyrophosphorylase starch synthesis pathway in leaf mesophyll chloroplasts or sugar transporters at the plastid membrane, such as glucose-6-phosphate/phosphate translocators, which are active in heterotrophic tissues. We demonstrate that GCs have metabolic features of both photoautotrophic and heterotrophic cells.

The Thioredoxin-Regulated α-Amylase 3 of Is a Target of S-Glutathionylation.

Reactive oxygen species (ROS) are produced in cells as normal cellular metabolic by-products. ROS concentration is normally low, but it increases under stress conditions. To stand ROS exposure, organisms evolved series of responsive mechanisms.

Regulation of Leaf Starch Degradation by Abscisic Acid Is Important for Osmotic Stress Tolerance in Plants.

Starch serves functions that range over a timescale of minutes to years, according to the cell type from which it is derived. In guard cells, starch is rapidly mobilized by the synergistic action of β-AMYLASE1 (BAM1) and α-AMYLASE3 (AMY3) to promote stomatal opening. In the leaves, starch typically accumulates gradually during the day and is degraded at night by BAM3 to support heterotrophic metabolism.

Blue Light Induces a Distinct Starch Degradation Pathway in Guard Cells for Stomatal Opening.

Stomatal pores form a crucial interface between the leaf mesophyll and the atmosphere, controlling water and carbon balance in plants [1]. Major advances have been made in understanding the regulatory networks and ion fluxes in the guard cells surrounding the stomatal pore [2]. However, our knowledge on the role of carbon metabolism in these cells is still fragmentary [3-5].

Gibberellic acid signaling is required for ambient temperature-mediated induction of flowering in Arabidopsis thaliana.

Distinct molecular mechanisms integrate changes in ambient temperature into the genetic pathways that govern flowering time in Arabidopsis thaliana. Temperature-dependent eviction of the histone variant H2A.Z from nucleosomes has been suggested to facilitate the expression of FT by PIF4 at elevated ambient temperatures.

Spatial control of flowering by DELLA proteins in Arabidopsis thaliana.

The transition from vegetative to reproductive development is a central event in the plant life cycle. To time the induction of flowering correctly, plants integrate environmental and endogenous signals such as photoperiod, temperature and hormonal status. The hormone gibberellic acid (GA) has long been known to regulate flowering.

Gibberellin regulates the Arabidopsis floral transition through miR156-targeted SQUAMOSA promoter binding-like transcription factors.

Gibberellin (GA), a diterpene hormone, plays diverse roles in plant growth and development, including seed germination, stem elongation, and flowering time. Although it is known that GA accelerates flowering through degradation of transcription repressors, DELLAs, the underlying mechanism is poorly understood. We show here that DELLA directly binds to microRNA156 (miR156)-targeted SQUAMOSA PROMOTER BINDING-LIKE (SPL) transcription factors, which promote flowering by activating miR172 and MADS box genes.