The Role of Phytocyanins in Secondary Cell Wall Assembly and their Potential Uses in Biofuel Production

  • Angelo Peralta

    Student thesis: Master of Philosophy


    Lignocellulosic material is an important feedstock for second generation biofuels. Most of the sugar is in the form of cellulose that is embedded in a matrix of hemicelluloses and lignin and because of this, the hydrolysis of cellulose is hindered. Lignin, while benefitting the plant by providing essential structural support and helping prevent pathogen attack, also hinders cellulose digestibility and confers a need for pretreatment of biomass prior to saccharification. A key understanding of lignin polymerisation and synthesis would lead to manipulation of cell walls better amenable to saccharification for biofuel production. It has been proposed that phytocyanins- copper containing redox enzymes may function in the lignification of plant secondary cell walls. To investigate whether phytocyanins are involved in lignifying tissues, a reverse genetics approach using T-DNA inserts and artificial microRNA silencing was used to generate mutants. These were screened for evidence of defects in secondary cell wall deposition. Collapsed xylem vessels were observed in an RNAi line indicative of a cell wall defect. Expression data suggests that in this line two additional phytocyanin genes as well as the initial target gene are downregulated. Subcellular localisation, through GFP-tagging and fluorescence microscopy also revealed their localisation in the cell wall. Metabolic analysis by FTIR spectroscopy also demonstrated that phytocyanin mutants have a similar biochemical profile as other known lignin deficient mutants. However, phytocyanins display a significant degree of functional redundancy as multiple gene knockdowns were needed to elicit an observable phenotype. With the putative role of phytocyanins established, manipulation of these enzymes could be used to generate less recalcitrant biomass sources that require less pretreatment and exhibit increased saccharification efficiency to produce more economically viable biofuels.
    Date of Award1 Aug 2014
    Original languageEnglish
    Awarding Institution
    • The University of Manchester
    SupervisorSimon Turner (Supervisor) & Jon Pittman (Supervisor)

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