PLANT PHYSIOLOGY , Vol 106, Issue 3 917-928, Copyright © 1994 by American Society of Plant Biologists
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ENVIRONMENTAL AND STRESS PHYSIOLOGY |
Regulation of BN115, a Low-Temperature-Responsive Gene from Winter Brassica napus
T. C. White, D. Simmonds, P. Donaldson and J. Singh
Plant Research Centre, Agriculture Canada, Ottawa, Ontario, Canada, K1A 0C6
The genomic clone for BN115, a low-temperature-responsive gene, was
isolated from winter Brassica napus and its sequence was determined. A
1.2-kb fragment of the 5[prime] regulatory region (from bp -1107 to +100)
was fused to the [beta]-glucuronidase (GUS) reporter gene and
BN115-promoted GUS expression was observed in green tissues of transgenic
B. napus plants only after incubation at 2[deg]C. No expression was
observed after incubation at 22[deg]C, either in the presence or the
absence of ABA. Microprojectile bombardment of winter B. napus leaves with
a BN115 promoter/GUS construct yielded similar results and was used to
analyze a series of deletions from the 5[prime] end of the promoter.
Results obtained from transient expression studies showed that the
low-temperature regulation of BN115 expression involves a possible enhancer
region between bp -1107 and -802 and a second positive regulatory region
located between bp -302 and -274. Deletion analyses and results from
replacement with a truncated cauliflower mosaic virus 35S promoter suggest
that the minimal size required for any maintenance of low-temperature GUS
expression is a -300-bp fragment. Within this fragment are two 8-bp
elements with the sequence TGGCCGAC, which are identical to those present
in the positive regulatory region of the promoter of the homologous
Arabidopsis cor15a gene and to a 5-bp core sequence in the low-temperature-
and dehydration-responsive elements identified in the promoter regions of
several cold-responsive Arabidopsis thaliana genes.
