Author ORCID Identifier

Date Available


Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Agriculture, Food and Environment


Plant and Soil Sciences

First Advisor

Dr. Arthur G. Hunt


Messenger RNA polyadenylation, the process wherein the primary RNA polymerase II transcript is cleaved and a poly(A) tract added, is a key step in the expression of genes in plants. Polyadenylation is mediated by a complex (the polyadenylation complex, or PAC) that consists of between 15 and 20 subunits. To learn the roles of PAC in regulation of the polyadenylation in plants, I conducted a survey of variability in the plant PAC. For this, I drew upon a database of naturally-occurring variation in numerous geographic isolates of Arabidopsis thaliana. The results show that many subunits of the PAC are conserved, and several of them are selected for new or altered function. Interestingly, some genes purported to encode PAC subunits in Arabidopsis are actually pseudogenes.

The Arabidopsis thaliana ortholog of the 30-kD subunit of the mammalian Cleavage and Polyadenylation Specificity Factor (CPSF30) gene encodes two proteins, CPSF30S and CPSF30L. To better understand the function of CPSF30S and CPSF30L in abiotic and biotic stress responses, I subjected the set of mutant and complemented Arabidopsis lines to salt, drought, oxidative stress and systemic acquired resistance (SAR). The results show that CPSF30S and CPSF30L have different functions in response to stress treatments. CPSF30L is required for alternative polyadenylation (APA) in salt stress. CPSF30S is acting downstream from the initial challenge by the avirulent pathogen and outside of the inoculated leaf. Taken together, these results provide new insights into the connections between mRNA polyadenylation and the plant environment signal.

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