PLANT PHYSIOLOGY , Vol 102, Issue 4 1337-1340, Copyright © 1993 by American Society of Plant Biologists
Isolation and Characterization of a cDNA Clone for a Harvest-Induced Asparagine Synthetase from Asparagus officinalis L
K. M. Davies and G. A. King
New Zealand Institute for Crop & Food Research Limited, Levin Research Centre, Private Bag 4005, Levin, New Zealand
A full-length cDNA clone (pTIP27) encoding asparagine synthetase (AS; EC
6.3.5.4) was isolated from a cDNA library prepared from the tip section
(apex to 30 mm) of Asparagus officinalis L. spears. The cDNA clone encodes
an mRNA of 1978 bp, giving a derived protein of 66.5 kD molecular mass. The
derived amino acid sequence is 81% homologous to AS from Pisum sativum.
Only low levels of transcript for AS could be detected in growing spears,
roots, or ferns. However, AS mRNA levels began to increase in the tips of
harvested spears after 2 h at 20[deg]C, and in the other sections of the
spear after 4 h, suggesting that all sections of the spear were responding
to the same postharvest signal. The results are discussed in relation to
metabolic changes occurring in harvested spears.
