On May 2, 2016 (Beijing time), Molecular Plant online published a research paper entitled “DELLA proteins promote anthocyanin biosynthesis through sequestering MYBL2 and JAZ repressors of the MYB/bHLH/WD40 complex in Arabidopsis thaliana”, from Prof. Jirong Huang’s group of Institute of Plant Physiology and Ecology (SIPPE), Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences. Through analyzing the molecular mechanism underlying gibberellic acid (GA)-regulated anthocyanin biosynthesis, authors revealed that plants adapt to environmental changes via modulating the biosynthesis of secondary metabolites.

 

As sessile organisms, plants produce an enormous variety of secondary metabolites that are essential for their precise responses to changing environment and survival under stresses. Anthocyanins, a class of phenypropanoids distributed ubiquitously higher plants, endow flowers, fruits, stems, and leaves with a colorful world from red, purple to blue. They protect plants against UV radiation, high light, freezing, and nutritional deficient stresses, as well as playing an important role in the plant-insect interactions. Thus, accumulation of anthocyanins is regarded as a visible biomarker to judge whether or not plant growth encounters with various stresses. However, the molecular mechanisms of stress-induced anthocyanin biosynthesis are largely unknown.

 

In order to adapt to adverse growth conditions, plants sacrifice growth to facilitate the biosynthesis of secondary metabolites, thereby balancing the process of growth and defense. GA is an important phytohormone to promote plant growth. DELLA proteins are key repressors of GA signaling transduction. Under stress conditions, the decreased levels of endogenous GA facilitate the accumulation of DELLA proteins, resulting in slow growth and accumulation of anthocyanins, which finally facilitates plant survival. Thus, the question is how DELLA proteins coordinately regulate plant growth and defense?

 

Under the guidance of Prof. Jirong Huang, PhD students, represented by Ye Xie (first author), investigated the molecular mechanism of DELLA-regulated anthocyanin biosynthesis using multiple genetic, physiological, molecular and biochemical techniques. They found that, under diverse abiotic stresses such as freezing, low nitrogen or phosphate, the accumulated DELLA proteins directly bind to MYBL2 and JAZ proteins, two suppressors of MYB/bHLH/WD40 transcriptional activation complex involved in the anthocyanin biosynthetic pathway. Such protein-protein interactions sequester MYBL2/JAZs, leading to MBW complex formation, which activates the expression of anthocyanin biosynthetic genes, and then promote anthocyanin accumulation. This study reveals a new molecular mechanism by which plants dynamically regulated the balance between plant growth and adaption to environmental stresses through anthocyanin biosynthesis. This project is financially supported by the National 973 Program and Natural Science Foundation. (Institute of Plant Physiology and Ecology, SIPPE)

 

Contact: 
Huang Jirong, PhD, Professor
Institute of Plant Physiology & Ecology
Shanghai Institutes for Biological Sciences
Chinese Academy of Sciences 
300 Fenglin Road
Shanghai 200032, China