Open AccessIdentification and overexpression of gibberellin 2‐oxidase ( GA 2ox ) in switchgrass ( P anicum virgatum L.) for improved plant architecture and reduced biomass recalcitrance
Author(s) -
Wuddineh Wegi A.,
Mazarei Mitra,
Zhang Jiyi,
Poovaiah Charleson R.,
Mann David G. J.,
Ziebell Angela,
Sykes Robert W.,
Davis Mark F.,
Udvardi Michael K.,
Stewart Charles Neal
Publication year - 2015
Publication title -
plant biotechnology journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.525
H-Index - 115
eISSN - 1467-7652
pISSN - 1467-7644
DOI - 10.1111/pbi.12287
Subject(s) - lignin , panicum virgatum , gibberellin , biology , biomass (ecology) , genetically modified crops , lignocellulosic biomass , botany , transgene , gene , bioenergy , biofuel , food science , biochemistry , microbiology and biotechnology , agronomy
Summary Gibberellin 2‐oxidases ( GA 2oxs) are a group of 2‐oxoglutarate‐dependent dioxygenases that catalyse the deactivation of bioactive GA or its precursors through 2β‐hydroxylation reaction. In this study, putatively novel switchgrass C 20 GA 2ox genes were identified with the aim of genetically engineering switchgrass for improved architecture and reduced biomass recalcitrance for biofuel. Three C 20 GA 2ox genes showed differential regulation patterns among tissues including roots, seedlings and reproductive parts. Using a transgenic approach, we showed that overexpression of two C20 GA2ox genes, that is PvGA2ox5 and PvGA2ox9 , resulted in characteristic GA‐deficient phenotypes with dark‐green leaves and modified plant architecture. The changes in plant morphology appeared to be associated with GA2ox transcript abundance. Exogenous application of GA rescued the GA ‐deficient phenotypes in transgenic lines. Transgenic semi‐dwarf lines displayed increased tillering and reduced lignin content, and the syringyl/guaiacyl lignin monomer ratio accompanied by the reduced expression of lignin biosynthetic genes compared to nontransgenic plants. A moderate increase in the level of glucose release in these transgenic lines might be attributed to reduced biomass recalcitrance as a result of reduced lignin content and lignin composition. Our results suggest that overexpression of GA 2ox genes in switchgrass is a feasible strategy to improve plant architecture and reduce biomass recalcitrance for biofuel.