Date of Award

Winter 2006

Project Type

Thesis

Program or Major

Genetics

Degree Name

Master of Science

First Advisor

Estelle Hrabak

Abstract

Calcium-dependent protein kinases (CDPKs) are a group of plant serine-threonine kinases that are stimulated in response to increases in intracellular calcium concentrations. Physcomitrella patens is a moss and a member of the bryophyte family. Physcomitrella has gained popularity as a model research organism due to the simple morphology of the plant as well as many other desirable characteristics. My research utilized Physcomitrella to accomplish four goals. The first goal was to identify and obtain sequence for as many CDPKs as possible in Physcomitrella. The second goal was to confirm the calcium-activated protein kinase activity of the identified CDPKs. The third goal consisted of two parts: first, to determine the expression pattern of a specific CDPK (CPK6) and second, to determine the role of a 5' UTR intron in CPK6 expression. The fourth goal was to silence expression of CPK6, and possibly other closely related CDPKs, by RNA interference (RNAi) in order to screen for a phenotype.

My results showed that there are at least 16 CDPKs in Physcomitrella patens. Two of those CDPKs were tested and displayed calcium-activated protein kinase activity. Expression analysis of CPK6 showed strongest expression in protonemal tip cells, immature phyllids, base of the gametophore at the site of protonemal attachment, and occasionally in axillary hair cells. Weaker expression was seen in non-tip protonemal cells and mature phyllids. Removal of the 5' UTR intron resulted in overall decreased expression levels, but did not change the expression pattern. RNAi results indicated that the RNAi response pathway was activated, however no phenotype was observed under normal growth conditions.

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