New Zealand Journal of Crop and Horticultural Science abstracts
Asparagine synthetase gene expression
increases as sucrose declines in broccoli after harvest
CHRISTOPHER G. DOWNS
SHERYL D. SOMERFIELD
New Zealand Institute for Crop & Food
Research Limited
Levin Research Centre
Private Bag 4005
Levin, New Zealand
Abstract Broccoli (Brassica oleracea L.) floral
tissues rapidly differentiate and grow before harvest and then senesce rapidly
after harvest. The factors regulating this rapid postharvest senescence are
currently under investigation. We show that within 6 h of harvest sucrose
concentration in florets declines by c. 50%, and between 24 and 72 h
asparagine levels increase more than 7-fold. This increase in asparagine
parallels an earlier increase in asparagine synthetase (AS) gene expression in
florets. Northern analyses show that AS transcript abundance increases from 2
to 24 h after harvest, and then declines. AS transcript abundance also
increases in harvested leaves as they turn yellow, although to a level lower
than that seen in florets. In other plant systems, including asparagus,
increases in AS gene expression occur as a result of a decline in sucrose
status. We note the considerable similarities between broccoli and asparagus
postharvest physiology and discuss our results for broccoli AS in terms of
possible regulation by sucrose status.
Keywords asparagine; asparagine synthetase; broccoli;
postharvest; sucrose
New Zealand Journal of Crop and Horticultural Science, 1997, Vol. 25:
191-195
0114-0671/97/2502-0191 $7.00/0 (c) The Royal Society of New Zealand
1997
Short communication
PDF file of entire paper: medium quality (1261K); (scanned from paper original: notes about this process)
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