Theses and Dissertations


Hana Mujahid

Issuing Body

Mississippi State University


Peng, Zhaohua

Date of Degree


Original embargo terms

MSU Only Indefinitely

Document Type

Dissertation - Campus Access Only


Molecular Biology

Degree Name

Doctor of Philosophy


College of Agriculture and Life Sciences


Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology


Although the cell wall is an essential plant cell structure influencing several important aspects of plant development, little is known about the genes and proteins that regulate its structure and function. In this dissertation, we first examined the regulation of the nuclear proteome of rice (Oryza sativa) in response to cell wall removal. Using labelree comparative proteome analysis we found that, upon removal of the cell wall, 142 nuclear proteins were up regulated and 112 nuclear proteins were down regulated. The differentially expressed proteins included transcription factors, histones, histone domain containing proteins, and histone modification enzymes. This study led to a novel discovery that removal of the cell wall results in dynamic changes in the nuclear proteome affecting the regulation of proteins involved in various molecular processes such as chromatin and nucleosome assembly, protein-DNA complex assembly, and DNA packaging. To further study cell wall development, we utilized the unique features of cotton fiber and performed a proteomic study using four stages during cotton fiber cell wall development including 10 days post anthesis (dpa), 15 dpa, 25 dpa, and 35 dpa. In addition, we aimed to improve protein extraction for recalcitrant fiber stages using pressure cycling technology (PCT). To our knowledge, this study identified the largest number of proteins and differentially expressed proteins in the G. hirsutum cotton species including the 35 dpa fiber proteome which has not been examined in prior reports. Additionally, in order to identify key genes regulating cell wall cellulose content, a mutant with a substantial reduction in cellulose was characterized in Arabidopsis. It was found that the mutated gene was VHA-E1. We found that the VHA-E1 protein formed a distinct plate in the boundary of two fusion-destined vacuoles to tether vacuoles together. The eventual vacuole fusion was achieved by pinching off the vacuole-boundary plate producing a stable membrane-bound intravacuolar globoid. These observations demonstrate that VHA-E1 may be involved in a novel cellular process regulating fusion of vacuoles by forming a cellular structure referred to as the vacuole boundary plate. Altogether, these findings suggest plant vacuole fusion and central vacuole biogenesis involve an unprecedented mechanism in Arabidopsis.