Powerful regulatory systems and post-transcriptional gene silencing resist increases in cellulose content in cell walls of barley

BMC Plant Biology

Research Article

Neil J Shirley¹  Marilyn Henderson¹  Hwei-Ting Tan¹  Rohan R Singh¹  Geoffrey B Fincher¹  Rachel A Burton¹  Gwenda M Mayo²  Kanwarpal S Dhugga³ 

[1] ARC Centre of Excellence in Plant Cell Walls, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, 5064, Glen Osmond, South Australia, Australia;Adelaide Microscopy Waite Facility, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, 5064, Glen Osmond, South Australia, Australia;DuPont Agricultural Biotechnology, DuPont Pioneer, 50131-1004, Johnston, IA, USA;

关键词: Barley;    CaMV 35S constitutive promoter;    Cellulose;    Gene silencing;    HvCesA;    Primary cell walls;    Secondary cell walls;   

DOI  :  10.1186/s12870-015-0448-y

 received in 2014-10-07, accepted in 2015-02-03,  发布年份 2015

来源: Springer

【 摘 要 】

BackgroundThe ability to increase cellulose content and improve the stem strength of cereals could have beneficial applications in stem lodging and producing crops with higher cellulose content for biofuel feedstocks. Here, such potential is explored in the commercially important crop barley through the manipulation of cellulose synthase genes (CesA).ResultsBarley plants transformed with primary cell wall (PCW) and secondary cell wall (SCW) barley cellulose synthase (HvCesA) cDNAs driven by the CaMV 35S promoter, were analysed for growth and morphology, transcript levels, cellulose content, stem strength, tissue morphology and crystalline cellulose distribution. Transcript levels of the PCW HvCesA transgenes were much lower than expected and silencing of both the endogenous CesA genes and introduced transgenes was often observed. These plants showed no aberrant phenotypes. Although attempts to over-express the SCW HvCesA genes also resulted in silencing of the transgenes and endogenous SCW HvCesA genes, aberrant phenotypes were sometimes observed. These included brittle nodes and, with the 35S:HvCesA4 construct, a more severe dwarfing phenotype, where xylem cells were irregular in shape and partially collapsed. Reductions in cellulose content were also observed in the dwarf plants and transmission electron microscopy showed a significant decrease in cell wall thickness. However, there were no increases in overall crystalline cellulose content or stem strength in the CesA over-expression transgenic plants, despite the use of a powerful constitutive promoter.ConclusionsThe results indicate that the cellulose biosynthetic pathway is tightly regulated, that individual CesA proteins may play different roles in the synthase complex, and that the sensitivity to CesA gene manipulation observed here suggests that in planta engineering of cellulose levels is likely to require more sophisticated strategies.

【 授权许可】

Unknown   
© Tan et al.; licensee BioMed Central. 2015. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.