Qiaoyun He1, Zheng Zeng1, Fu Li1, Renyan Huang2, Yanzhou Wang1, Touming Liu3. 1. Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha, 410205, China. 2. Hunan Institute of Plant Protection, Changsha, 410125, China. 3. Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha, 410205, China. liutouming@caas.cn.
Abstract
MAIN CONCLUSION: A total of 249 sites from 197 proteins showed a differential ubiquitination level in the fiber development of ramie barks. The function of two differentially ubiquitinated proteins for fiber growth was demonstrated. Ubiquitination is one of the most common post-translational modifications of proteins, and it plays essential roles in plant growth and development. However, the involvement of ubiquitination in the growth of plant fibers remains largely unknown. We compared the ubiquitylome of the top and middle stems of ramie bark, with different fiber growth stages. We identified 249 differentially ubiquitinated sites in 197 proteins in fiber-developing barks in the stems and found that seven were homologs of Arabidopsis proteins associated with fiber growth. Overexpression of the differentially ubiquitinated proteins, RWA3 homolog whole_GLEAN_10024150 and MYB protein whole_GLEAN_10015497, significantly promoted fiber growth in transgenic Arabidopsis, indicating their involvement in this process. We also found that the abundance of these proteins decreased when their ubiquitination levels increased and vice versa in the fiber-developing bark. These results indicated that the abundance of these two proteins was adjusted through ubiquitin-dependent degradation. Collectively, our findings provide important insights into the involvement of ubiquitination in the growth of ramie fibers.
MAIN CONCLUSION: A total of 249 sites from 197 proteins showed a differential ubiquitination level in the fiber development of ramie barks. The function of two differentially ubiquitinated proteins for fiber growth was demonstrated. Ubiquitination is one of the most common post-translational modifications of proteins, and it plays essential roles in plant growth and development. However, the involvement of ubiquitination in the growth of plant fibers remains largely unknown. We compared the ubiquitylome of the top and middle stems of ramie bark, with different fiber growth stages. We identified 249 differentially ubiquitinated sites in 197 proteins in fiber-developing barks in the stems and found that seven were homologs of Arabidopsis proteins associated with fiber growth. Overexpression of the differentially ubiquitinated proteins, RWA3 homolog whole_GLEAN_10024150 and MYB protein whole_GLEAN_10015497, significantly promoted fiber growth in transgenic Arabidopsis, indicating their involvement in this process. We also found that the abundance of these proteins decreased when their ubiquitination levels increased and vice versa in the fiber-developing bark. These results indicated that the abundance of these two proteins was adjusted through ubiquitin-dependent degradation. Collectively, our findings provide important insights into the involvement of ubiquitination in the growth of ramie fibers.
Authors: Elizabeth Brill; Michel van Thournout; Rosemary G White; Danny Llewellyn; Peter M Campbell; Steven Engelen; Yong-Ling Ruan; Tony Arioli; Robert T Furbank Journal: Plant Physiol Date: 2011-07-14 Impact factor: 8.340