DRB2 modulates leaf rolling by regulating accumulation of MicroRNAs related to leaf development in rice

Zhaodi Yuan#, Jihong Pan#, Congping Chen, Yulin Tang, Hongshan Zhang, Jia Guo, Xiaorong Yang, Longfei Chen, Chunyan Li, Ke Zhao, Qian Wang, Bin Yang, Changhui Sun, Xiaojian Deng*, Pingrong Wang*.

International Journal of Molecular Sciences (TOP, IF=6.208), 2022

https://doi.org/10.3390/ijms231911147

Abstract

As an important agronomic trait in rice (Oryza sativa), moderate leaf rolling helps to maintain the erectness of leaves and minimize shadowing between leaves, leading to improved photosynthetic efficiency and grain yield. However, the molecular mechanisms underlying rice leaf rolling still need to be elucidated. Here, we isolated a rice mutant, rl89, showing adaxially rolled leaf phenotype due to decreased number and size of bulliform cells. We confirmed that the rl89 phenotypes were caused by a single nucleotide substitution in OsDRB2 (LOC_Os10g33970) gene encoding DOUBLE-STRANDED RNA-BINDING2. This gene was constitutively expressed, and its encoded protein was localized to both nucleus and cytoplasm. Yeast two-hybrid assay showed that OsDRB2 could interact with DICER-LIKE1 (DCL1) and OsDRB1-2 respectively. qRT-PCR analysis of 29 related genes suggested that defects of the OsDRB2-miR166-OsHBs pathway could play an important role in formation of the rolled leaf phenotype of rl89, in which OsDRB2 mutation reduced miR166 accumulation, resulting in elevated expressions of the class III homeodomain-leucine zipper genes (such as OsHB1, 3 and 5) involved in leaf polarity and/or morphology development. Moreover, OsDRB2 mutation also reduced accumulation of miR160, miR319, miR390, and miR396, which could cause the abnormal leaf development in rl89 by regulating expressions of their target genes related to leaf development.

Keywords: rice (Oryza sativa); leaf rolling; bulliform cell; microRNA; DRB2; leaf development