J Integr Plant Biol. ›› 2015, Vol. 57 ›› Issue (1): 106-119.DOI: 10.1111/jipb.12303

• Research Articles • Previous Articles     Next Articles

The kinesin-like proteins, KAC1/2, regulate actin dynamics underlying chloroplast light-avoidance in Physcomitrella patens

Zhiyuan Shen1, Yen-Chen Liu1, Jeffrey P. Bibeau1, Kyle P. Lemoi2, Erkan Tüzel2 and Luis Vidali1*   

  1. 1Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
    2Department of Physics, Worcester Polytechnic Institute, Worcester, Massachusetts, USA
  • Received:2014-08-19 Accepted:2014-10-23 Published:2015-01-01
  • About author:*Correspondence: E-mail: lvidali@wpi.edu

Abstract:

In plants, light determines chloroplast position; these organelles show avoidance and accumulation responses in high and low fluence-rate light, respectively. Chloroplast motility in response to light is driven by cytoskeletal elements. The actin cytoskeleton mediates chloroplast photorelocation responses in Arabidopsis thaliana. In contrast, in the moss Physcomitrella patens, both, actin filaments and microtubules can transport chloroplasts. Because of the surprising evidence that two kinesin-like proteins (called KACs) are important for actin-dependent chloroplast photorelocation in vascular plants, we wanted to determine the cytoskeletal system responsible for the function of these proteins in moss. We performed gene-specific silencing using RNA interference in P. patens. We confirmed existing reports using gene knockouts, that PpKAC1 and PpKAC2 are required for chloroplast dispersion under uniform white light conditions, and that the two proteins are functionally equivalent. To address the specific cytoskeletal elements responsible for motility, this loss-of-function approach was combined with cytoskeleton-targeted drug studies. We found that, in P. patens, these KACs mediate the chloroplast light-avoidance response in an actin filament-dependent, rather than a microtubule-dependent manner. Using correlation-decay analysis of cytoskeletal dynamics, we found that PpKAC stabilizes cortical actin filaments, but has no effect on microtubule dynamics.

 

Shen Z, Liu YC, Bibeau JP, Lemoi KP, Tüzel E, Vidali L (2015) The kinesin-like proteins, KAC1/2, regulate actin dynamics underlying chloroplast light-avoidance in Physcomitrella patens. J Integr Plant Biol 57: 106–119. doi: 10.1111/jipb.12303

Key words: Actin filaments, cytoskeleton, intracellular transport, kinesin-14, light-avoidance response, microtubule, moss, RNAi

Editorial Office, Journal of Integrative Plant Biology, Institute of Botany, CAS
No. 20 Nanxincun, Xiangshan, Beijing 100093, China
Tel: +86 10 6283 6133 Fax: +86 10 8259 2636 E-mail: jipb@ibcas.ac.cn
Copyright © 2021 by the Institute of Botany, the Chinese Academy of Sciences
Online ISSN: 1744-7909 Print ISSN: 1672-9072 CN: 11-5067/Q
备案号:京ICP备16067583号-22