Date of Award


Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Biological Sciences (PhD)

Administrative Home Department

Department of Biological Sciences

Advisor 1

Chandrashekhar P. Joshi

Committee Member 1

Guiliang Tang

Committee Member 2

Rupali Datta

Committee Member 3

Ashutosh Tiwari


Lignins are second most abundant components of vascular plant cell walls. They provide plants with structural rigidity and are polymers of monolignols. Lignin polymerization is catalyzed by peroxidases and/or laccases. These enzymes are suggested to share functional overlap and mechanism by which they coordinate this process is not clearly understood. There are about 100 peroxidases and 50 laccase genes known in poplar genome out of which some stem differentiating xylem-specific (SDX) enzymes were selected for our study. The main objective was to genetically manipulate genes expressed in the SDX region in the cell wall to see the effects on lignin content in the wood without affecting yield of the transgenic poplar trees. We also aimed to understand the role these enzymes play during lignin polymerization. We also adopted the short tandem target mimic (STTM) strategy to manipulate miRNAs that might be involved in wood development of poplar trees. Our results indicate that peroxidases, laccases and miRNAs under investigation play some specific roles in secondary cell wall biosynthesis. Therefore, manipulation of expression of these genes may prove beneficial towards future genetic engineering of the poplar trees for improved downstream applications.