regulation of arabidopsis tga transcription factors by cysteine ...

BABA respond to pathogen infection by rapidly increasing the expression of PR genes.
Another feature that sets BABA resistance apart from the other two types is the ability to
not only protect the plant from biotic stress but also from abiotic stress (Jakob et al.,
2005).
One of the underlying themes of induced disease resistance in the last few years
is the cross-talk that exists between the three types of resistance. Although each appears
to have its unique characteristics, genes and molecules that were once thought to be
exclusive to one type of resistance appear to also possess a role in one or both of the
other types (Pieterse and Van Loon, 2004).
2.4 TGA factors in SAR
2.4.1 The as-1 element
TGA factors were first identified through their ability to bind to the activating
sequence 1 (as-1) element of the Cauliflower Mosaic Virus (CaMV) 35S promoter
(Katagiri et al., 1989). It is from the as-1 element, composed of two TGACG motifs
spaced eight nucleotides apart, that TGA factors derive their name. Research done
concurrently found that TGA factors were also able to bind a similar element found in
the octopine synthase (ocs) promoter from the Agrobacterium tumefaciens tumour-
inducing (Ti) plasmid (Fromm et al., 1989). Consequently some of the TGA factors
were first referred to as Octopine Binding Factors (OBF) (Zhang et al., 1993); however
they will be referred to as TGA factors in this thesis.
The as-1 element has been found to be important in the regulation of glutathione
S-transferase 6 (GST-6) (Strompen et al., 1998) as well as PR-1 (Lebel et al., 1998). It
has also been found to be over-represented in the promoters of genes differentially
8