Production and characterisation of transgenic maize plants with altered lignocellulosic biomass for improved biorefining features

  • Rakesh Bhatia

Student thesis: Doctoral ThesisDoctor of Philosophy

Abstract

Secondary cell wall biosynthesis related genes including MYB and NAC transcription factors as well as glycosyltransferases represent potential genetic engineering targets for the production of lignocellulosic biomass with improved biorefining features. This study investigated the putative function of ZmNAC23, ZmNAC48, ZmNAC110, ZmMYB167 and ZmGT61 in secondary cell wall biosynthesis using a constitutive overexpression approach and evaluated the effects of their overexpression on biomass characteristics. Results showed that plants transformed with ZmNAC23, ZmNAC48 and ZmNAC110 exhibit significantly reduced plant stature and biomass yield, as well as altered tissue patterning and/or degree of lignification in their stems. Transgenic plants constitutively overexpressing ZmGT61 hint towards alteration in xylooligosaccharide abundances. Overexpression of ZmMYB167 affects monolignol and phenylpropanoid biosynthesis and alters p-coumarate, ferulate and lignin content in maize. Taken together, these results suggest (i) a potential role for ZmNAC23, ZmNAC48 and ZmNAC110 in plant growth and development processes that could affect secondary cell wall biosynthesis, (ii) ZmGT61 as a candidate for involvement in grass-specific secondary cell wall xylan biosynthesis (iii) ZmMYB167 as a target for manipulation of lignification in lignocellulosic biomass. Collectively, this study highlights that use of the overexpression strategy seems effective in revealing informative secondary cell wall traits and/or plant phenotypes and that transgenic technologies could provide a route for future development of improved biorefining feedstocks. Nonetheless, one must be careful when assigning gene function because the cascade of genes influenced by overexpression directly or indirectly can be complex and hence requires additional supporting data such as from RNA interference or knockout mutant studies. It is also important to note that genetic manipulations can lead to adverse consequences on the growth and development of a transgenic crop.
Date of Award2016
Original languageEnglish
Awarding Institution
  • Aberystwyth University
SupervisorJoe Gallagher (Supervisor) & Maurice Bosch (Supervisor)

Keywords

  • Zea mays
  • grasses
  • transcription factors
  • MYB
  • NAC
  • glycosyltransferases
  • secondary cell walls
  • biorefining
  • genetic engineering

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