Research Highlights

• Subject Categories:
  • Developmental biology
  • Cell & molecular biology

Published online: 1 July 2009 | doi:10.1038/nchina.2009.136

Plant development: Split ends

Felix Cheung

Introduction

© (2009) Nature Cell Biology

Seedlings can grow much faster in darkness than in daylight. This is because seedlings are equipped with photoreceptors (light-sensitive proteins) that inhibit cell elongation in response to light. Hongxuan Lin at the Chinese Academy of Sciences in Shanghai and co-workers¹ have discovered that photoreceptors can also suppress the growth of seedlings through another pathway — cell division.

The halotolerance protein HAL3 (also known as SIS2) has a role in salt tolerance, cell integrity and in the cell cycle of plants. The rice Oryza sativa contains a HAL3-like gene, called OsHAL3. An overexpression of OsHAL3 (an abundance of OsHAL3 proteins) increases seedling growth and enhances salt tolerance in rice (see image, wild type on the left and various OsHAL3-overexpressed lines on the right).

The researchers found that light, especially blue light, suppresses the growth of rice seedlings by reducing the activity of OsHAL3. Their studies showed that blue light rapidly dissociates OsHAL3 trimers (the active form of OsHAL3), and regulates the transcriptional expression of OsHAL3.

Further studies revealed that OsHAL3 functions as a regulatory component in cell division. OsHAL3 enhances cell division and plant growth by recruiting and activating signalling proteins that lead to the degradation of cell cycle suppressors. Light suppresses this process by inactivating OsHAL3.

The findings reveal a previously unrecognized pathway for the photoreceptor regulation of plant growth.

The authors of this work are from:
National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, and SIBS–UC Berkeley Center for Molecular Life Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; Department of Plant and Microbial Biology, University of California, Berkeley, California, USA.

Reference

1. Sun, S. Y. et al. OsHAL3 mediates a new pathway in the light-regulated growth of rice. Nature Cell Biol. doi:10.1038/ncb1892 (2009). | Article |