1.  RNA regulation in the light signal transduction

Structural RNAs ranging from 50 to 300 nucleotides in size are widely present in eukaryotes, including nucleolar small RNAs and small nuclear RNAs etc. They serve as crucial regulators of gene expression, presenting several technical challenges for systematic identification in plants. We have overcome hurdles in biochemical separation of specific length RNAs, analysis of their molecular features, and high-throughput library construction. Pioneering studies in model plants such as rice and Arabidopsis have unveiled the expression, molecular characteristics, and evolutionary patterns of non-coding RNAs ranging from 50 to 300 nucleotides in size (Molecular Plant, 2013; Molecular Plant, 2014). The discovery of the first critical nucleolar small RNA with decreased expression resulting in significant defects in plant seedling growth and development has elucidated its regulatory mechanisms (PNAS, 2016). Through improved RNA biology techniques, we have identified and deciphered regulatory pathways parallel to known light signal-mediated genetic networks. We have discovered light signal-regulated non-coding RNA-ribonucleoprotein core complexes, ensuring the successful completion of light-controlled growth and development processes such as seed germination, de-etiolation, and seedling morphogenesis in Arabidopsis (PNAS, 2014; Sci. China. Life. Sci., 2018; Plant Cell, 2022). We have identified a molecular switch module, the BTE1 (barrier of transcription elongation 1) complex, which precisely suppresses gene expression, elucidating the correlation between epigenetic modifications on specific genes and the activity of the core transcription machinery in plants (PNAS, 2022).

2.  Interplay Regulation of Light Signals and Plant Hormone Signals

Light signals and plant hormone signals interact to regulate series of crucial physiological processes in plants. We have discovered that the COP1 (constitutively photomorphogenic 1)/SPA (suppressor of phyA-105) complex suppresses the activity of the key negative regulator of the brassinosteroid signaling pathway, the GSK3β protein kinase BIN2 (BRASSINOSTEROID-INSENSITIVE 2), under dark conditions, thereby inhibiting seedling photomorphogenesis (PNAS, 2017). Under light conditions, the E3 ubiquitin ligase COP1's substrate transcription factor HY5 enhances BIN2 kinase activity, thereby inhibiting hypocotyl elongation in seedlings (Nat. Commun., 2020). These studies expand the understanding of new regulatory nodes between light signals and phytohormone signals, laying important theoretical foundations for optimizing and utilizing crop light signal transduction modules.

Yuntong Jiao, Fengying Chen, Ruikai Zhang, Kai He, Qianru Mo, Shu Gao, Lei Su, Feiyang Sun