Abstract
Cotton fibers are highly elongated
single-cell, unbranched and non-glandular seed trichomes. Previous studies have
reported that the transcript level of GbEXPA2 is significantly up-regulated
during fiber cell elongation, suggesting that GbEXPA2 has an important function
in fiber development. In this study, the promoter of GbEXPA2 (839 bp) from the
DT sub-genome was isolated from Gossypium barbadense 3-79. Consistent with the
expression pattern of GbEXPA2, the promoter PGbEXPA2 was able to express GUS to
high levels in elongating fibers, but not in the root, stem, or leaf. In
Arabidopsis, GUS activity was only found in the rosette leaf trichomes and
rosette leaf vascular tissue, indicating that the transcription factors which
bind to PGbEXPA2 in the leaf trichomes of transgenic Arabidopsis were similar to
those found in cotton fiber. A deletion analysis of PGbEXPA2 revealed that a
461-bp fragment was sufficient to drive GUS expression in cotton fibers and
Arabidopsis rosette leaf trichomes. Exogenous phytohormonal treatments on
transgenic Arabidopsis with different promoter lengths (P-839, P-705, P-588 and
P-461) showed that GUS activity in Arabidopsis trichomes could be strongly
up-regulated by GA and, in contrast, down-regulated by ABA.
http://www.ncbi.nlm.nih.gov/pubmed/26001998