New Zealand Journal of Crop and Horticultural Science abstracts
Effect of the salivary proteinase from the New Zealand wheat bug, Nysius
huttoni, on various exotic and endemic plant seeds
D. EVERY
M. A. W. STUFKENS
New Zealand Institute for Crop & Food
Research Limited
Private Bag 4704
Christchurch, New Zealand
email: everyd@crop.cri.nz
Abstract The effect of
Nysius huttoni White feeding on
immature plant seeds was examined by caging the insect with the seed heads of
the following plants: wireweed (
Polygonum aviculare), twin cress
(
Coronopus didymus), yarrow (
Achillea millefolium), fathen
(
Chenopodium album), and native wheat grass. The largest seeds (wheat
grass and wireweed) were the most physically damaged with shrivelling and
colour changes. The amount of
N. huttoni proteinases in infested
seeds varied widely from 48 enzyme units/g wireweed seed to 8075 enzyme units/g
yarrow seed, but there appeared to be no relationship between proteinase
content and the amount of physical damage to the seeds. Sodium dodecyl sulphate
(SDS)-polyacrylamide gel electrophoresis showed that high levels of proteinase
in twin cress and yarrow seeds could hydrolyse protein subunits of a wide range
of molecular weights. In contrast, incubation of undamaged twin cress and
yarrow seeds with proteinase purified from
N. huttoni-damaged wheat
grain, did not hydrolyse any protein. The purified enzyme only hydrolysed high
molecular weight (HMW) protein subunits in wheat-grass seeds and wheat grain
(
Triticum aestivum), and possibly protein macropolymers in giant
spaniard (
Aciphylla scott-thomsonii) and koromiko (
Hebe
salicifolia) seeds. These HMW proteins in wheat grass, giant spaniard, and
koromiko seeds may have similar structure to the HMW glutenin subunits of wheat
grain. We conclude that when
N. huttoni feeds on some seeds it can
inject proteinases of a broader specificity range than the highly specific
proteinase found in
N. huttoni-damaged wheat, and we suggest that
particularly the latter enzyme has a role in softening the outer layers of
seeds to facilitate bug stylus penetration and maintain the flow of sap.
Keywords Nysius huttoni; proteinase; seed proteins;
wheat-bug damage; endemic plants; exotic plants
H99005
Received 29 January 1999; accepted 26 May 1999
PDF file of entire paper: medium quality (1365K); (scanned from paper original: notes about this process)
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