Title

Microarray Analysis of Differential Expression of Genes in Shoot Apex and Young Leaf of English Ivy (Hedera helix L. cv. Goldheart)

Date of Award

2010

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Biological Sciences

First Advisor

Scott O. Rogers, PhD

Second Advisor

Kit C. Chan, PhD (Committee Chair)

Third Advisor

Carmen F. Fioravanti, PhD (Committee Member)

Fourth Advisor

Helen Michaels, PhD (Committee Member)

Fifth Advisor

Paul F. Morris, PhD (Committee Member)

Abstract

Shoot apical meristems (SAMs) of higher plants maintain a population of pluripotent cells which continue to divide throughout the life of plant and provide cells for development of all the above-ground organs after embryogenesis. Since the plant is sessile, maintenance of stem cells in the SAM and appropriate differentiation are crucial for the plants to adapt to the changing environments. Shoot apex of the plant is the very tip of the shoot, in which the SAM resides. To analyze the differential gene expression patterns between the shoot apex and the very young leaf, transcriptomes from the two tissue types of a variegated variety of English ivy (Hedera helix L. cv. Goldheart) plants, were hybridized on Arabidopsis thaliana cDNA microarrays, using cross-species hybridization (CSH). Among 11,255 cDNA probes excluding ‘BLANK’ and ‘bad’ spots, 2,597 features produced signals that were greater than background levels, which constitutes 23% of the total number of usable probes on the microarray. One hundred seventy four genes were expressed statistically differentially (fold change >=2 and p=0.05). Of these, 60 were in the shoot apex and 114 were in the young leaf. Functional categorization based on the genome/protein databases and a pathway analysis revealed some of the tissue-specific biological processes and identified some of the genes involved. The annotated and/or predicted roles of those genes in the tissue-specific biological processes were described and discussed in relation to the plant development.