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Plant Molecular Genetics

Prof. Tony Kavanagh

Arabidopsis functional genomics

Transcriptional regulation of gene expression determines many aspect of plant growth and development. The genome of Arabidopsis thaliana codes for at least 1,600 transcription factors belonging to more than 45 gene families. Almost half of these are unique to plants but only approximately 6% have so far been characterized in terms of function. We are interested in members of the plant-specific NAC family (named for the genes NAM, ATAF1 and CUC), and the APETALA2 (AP2) family, members of which have been shown to be involved in regulating aspects of plant development and responses to abiotic (environmental) stress.

Overexpression of the NAXOS transcription factor gene alters leaf size and shape (A: overexpression; B: wild-type). NAXOS is expressed in leaves and embryos (C, D). Compared with GFP alone (E), the NAXOS-GFP fusion protein localizes in nuclei (F).

Chloroplast biology and biotechnology

Chloroplasts are the major photosynthetic and biosynthetic centers of the cell, responsible for the production of complex carbohydrates, amino acids, fatty acids and pigments. A leaf with 70 million cells typically contains 5 billion chloroplasts each of which contains up to 100 identical copies of a 155 kb plasmid-like genome. The ability to genetically transform chloroplasts opens up the possibility of studying chloroplast genome-encoded functions by targeted gene disruption, and many biotechnological opportunities including the genetic manipulation of chloroplasts for high-level production of recombinant proteins such as vaccines and antibodies. We are also interested in identifying nuclear genes whose products regulate chloroplast development.

Mutations in the nuclear genes SNOW WHITE (left) and LEMON (right) affect chloroplast development and function.

Recent publications

Zhou, F., Badillo-Corona, J. A., Karcher, D., Gonzalez-Rabade, N., Piepenburg, K., Borchers, A. M., Maloney, A. P., Kavanagh, T. A., Gray, J. C. & Bock, R. (2008). High-level expression of human immunodeficiency virus antigens from the tobacco and tomato plastid genomes. Plant Biotechnol J. (in press) PubMed.

Puthiyaveetil, S., Kavanagh, T. A., Cain, P., Sullivan, J. A., Newell, C. A., Gray, J. C., Robinson, C., van der Giezen, M., Rogers, M. B. & Allen, J. F. (2008). The ancestral symbiont sensor kinase CSK links photosynthesis with gene expression in chloroplasts. Proc. Natl. Acad. Sci. USA 105, 10061-10066. PubMed.

McDermott, P., Connolly, V. & Kavanagh, T. A. (2008). The mitochondrial genome of a cytoplasmic male sterile line of perennial ryegrass (Lolium perenne L.) contains an integrated linear plasmid-like element. Theor. Appl. Genet. 117, 459-470. PubMed.

Craig, W., Lenzi, P., Scotti, N., De Palma, M., Saggese, P., Carbone, V., McGrath Curran, N., Magee, A. M., Medgyesy, P., Kavanagh, T. A., Dix, P. J., Grillo, S. & Cardi, T. (2008). Transplastomic tobacco plants expressing a fatty acid desaturase gene exhibit altered fatty acid profiles and improved cold tolerance. Transgenic Res 17, 769-782. PubMed.

Sarmiento, C., Gomez, E., Meier, M., Kavanagh, T. A. & Truve, E. (2007). Cocksfoot mottle virus P1 suppresses RNA silencing in Nicotiana benthamiana and Nicotiana tabacum. Virus Res 123, 95-99. PubMed.

Magee, A. M., MacLean, D., Gray, J. C. & Kavanagh, T. A. (2007). Disruption of essential plastid gene expression caused by T7 RNA polymerase-mediated transcription of plastid transgenes during early seedling development. Transgenic Res 16, 415-428. PubMed.

Flannery, M. L., Mitchell, F. J., Coyne, S., Kavanagh, T. A., Burke, J. I., Salamin, N., Dowding, P. & Hodkinson, T. R. (2006). Plastid genome characterisation in Brassica and Brassicaceae using a new set of nine SSRs. Theor. Appl. Genet. 113, 1221-1231. PubMed.

Drea, S. C., Lao, N. T., Wolfe, K. H. & Kavanagh, T. A. (2006). Gene duplication, exon gain and neofunctionalization of OEP16-related genes in land plants. Plant J. 46, 723-735. PubMed.

Casas-Mollano, J. A., Lao, N. T. & Kavanagh, T. A. (2006). Intron-regulated expression of SUVH3, an Arabidopsis Su(var)3-9 homologue. J Exp Bot 57, 3301-3311. PubMed.

Heggie, L., Jansen, M. A., Burbridge, E. M., Kavanagh, T. A., Thorneley, R. N. & Dix, P. J. (2005). Transgenic tobacco (Nicotiana tabacum L. cv. Samsun-NN) plants over-expressing a synthetic HRP-C gene are altered in growth, development and susceptibility to abiotic stress. Plant Physiol Biochem 43, 1067-1073. PubMed.

Craig, W., Gargano, D., Scotti, N., Nguyen, T. T., Lao, N. T., Kavanagh, T. A., Dix, P. J. & Cardi, T. (2005). Direct gene transfer in potato: a comparison of particle bombardment of leaf explants and PEG-mediated transformation of protoplasts. Plant Cell Rep 24, 603-611. PubMed.

Magee, A. M., Coyne, S., Murphy, D., Horvath, E. M., Medgyesy, P. & Kavanagh, T. A. (2004). T7 RNA polymerase-directed expression of an antibody fragment transgene in plastids causes a semi-lethal pale-green seedling phenotype. Transgenic Res 13, 325-337. PubMed.

Kis, M., Burbridge, E., Brock, I. W., Heggie, L., Dix, P. J. & Kavanagh, T. A. (2004). An N-terminal peptide extension results in efficient expression, but not secretion, of a synthetic horseradish peroxidase gene in transgenic tobacco. Ann Bot (Lond) 93, 303-310. PubMed.

Lao, N. T., Long, D., Kiang, S., Coupland, G., Shoue, D. A., Carpita, N. C. & Kavanagh, T. A. (2003). Mutation of a family 8 glycosyltransferase gene alters cell wall carbohydrate composition and causes a humidity-sensitive semi-sterile dwarf phenotype in Arabidopsis. Plant Mol. Biol. 53, 687-701. PubMed.

Perry, A. S., Brennan, S., Murphy, D. J., Kavanagh, T. A. & Wolfe, K. H. (2002). Evolutionary re-organisation of a large operon in adzuki bean chloroplast DNA caused by inverted repeat movement. DNA Res. 9, 157-162. PubMed.

Magee, A. M. & Kavanagh, T. A. (2002). Plastid genes transcribed by the nucleus-encoded plastid RNA polymerase show increased transcript accumulation in transgenic plants expressing a chloroplast-localized phage T7 RNA polymerase. J Exp Bot 53, 2341-2349. PubMed.

Kirby, J. & Kavanagh, T. A. (2002). NAN fusions: a synthetic sialidase reporter gene as a sensitive and versatile partner for GUS. Plant J. 32, 391-400. PubMed.