Induction of phenylalanine ammonia-lyase (PAL5) in tomato (Lycopersicon esculentum) during early Verticillium albo-atrum colonization

Thumbnail Image



Saparno, Audrey M.

Journal Title

Journal ISSN

Volume Title


University of Guelph


The expression of the phenylalanine ammonia-lyase gene (PAL5) in tomato results from the differential utilization of two initiation sites. This thesis investigates whether a correlation exists between the differential expression of the two PAL5 transcripts and the plant's response to early colonization by Verticillium albo-atrum. Using an excised petiolar model system, expression in resistant and susceptible near-isolines of tomato was studied. Wounding alone resulted in an immediate but preferential transient induction for the short transcript. Though fungal colonization caused a similar response, the short transcript was induced even further relative to that seen with wounding; and this induction spanned a 24-hour period post infection. These trends occurred similarly in both isolines irrespective of the colonization pattern of V. albo-atrum. While PAL5 gene induction remains an important feature in the plant's response to stress, results indicate that the use of the two PAL5 initiation sites does not play a role in resistance of tomato to V. albo-atrum.



tomato, phenylalanine ammonia-lyase, verticillium albo-atrum, early colonization, stress