New Zealand Journal of Crop and Horticultural Science abstracts

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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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