Research

How does plant regulate their growth and development in response to environmental changes? 

The research goal of PBL is to elucidate molecular mechanisms by which plants sense and respond to environmental changes. 

[Research Topics]

1. Thermomorphogenesis
Plant constantly adjust their growth and development in response to their environments to maximize fitness and reproductive success. Temperature is one of the most influential environmental factors controlling plant fitness as it affects the rate of every physicochemical reaction. Prolonged exposure to warm temperatures triggers a set of developmental responses that are collectively referred to as thermomorphogenesis: plants exhibit increased elongation growth of the hypocotyl and primary root as well as accelerated flowering and seed set at warm temperatures. Temperature cues are not perceived in isolation but are integrated with a variety of other environmental and endogenous signals. In the context of signaling network, PBL research focuses on elucidating novel temperature-sensing mechanisms in plants.

2. Biomolecular phase separation

Like oil in water, once biomolecules such as proteins or RNA molecules reach a certain concentration, they can phase separate into liquid- or gel-like membraneless compartments in a cell. Biomolecular phase separation is emerging as an important principle for understanding the spatiotemporal organization of diverse biochemical reactions in living cells. Through liquid–liquid phase separation (LLPS), the physicochemical properties of biomolecules lead them to spontaneously cluster into liquid-like droplets and separate from their surrounding environment. Due to their liquid-like features, biomolecular condensates are capable of rapidly changing their molecular composition in response to environmental fluctuations. Phase separation could therefore serve as an environmental sensing mechanism. Because phase separation is intrinsically temperature responsive, it provides an intuitive mechanism for plants to sense thermal changes. 

The physicochemical properties of the PrD (prion-like domain) or IDR (intrinsically disordered region) structure allow proteins to reversibly switch between the dispersed and phase-separated forms in response to temperature changes. PBL utilizes the phase separation concept to study how PrD- or IDR-containing proteins are involved in temperature perception in plants.

3. Nucleocytoplasmic transport 

Nucleocytoplasmic transport, the exchange of matter between nucleus and cytoplasm, plays a fundamental role in plant response to environmental cues. The nucleus provides an opportunity for controlling gene expression through selective import or export of signaling molecules mediating environmental signals. The only gate for nucleocytoplasmic trafficking of signaling molecules between nucleus and cytoplasm is the nuclear pore complex (NPC). Loss-of-function mutants of NPC components exhibit a variety of phonotypes, presumably because the nucleocytoplasmic transport and activity of numerous signaling molecules is regulated by their interactions with NPC components. PBL research focuses on how NPC components contribute to sensing and responding to various abiotic stresses in plants.