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Effects of secretions of the mucus gland of Sirex Noctilio on biochemical systems in Pinus Radiata, and some physicochemical properties of the mucus

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Wong, LK (1977) Effects of secretions of the mucus gland of Sirex Noctilio on biochemical systems in Pinus Radiata, and some physicochemical properties of the mucus. PhD thesis, University of Tasmania.

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Abstract

The mucus secretion of S.noctilio induces a series of degradative
changes in the tissues of P.radiata needles, which result in chlorosis
and desiccation, and ultimtely death. Dramatic changes are recorded
in the respiratory rate and mode, and activities of amylase and peroxidase,
in tissues which develop severe symptoms. These changes are associated
with the destruction of chloroplasts, excessive loss of moisture
and necrosis of food conducting elements. Basic similarities between
changes caused by s.noctilio mucus, and natural and induced senescence
of other plant foliage are discussed, It is also suggested
that plant hormones confer a degree of resistance to the effects of
Sirex mucus.
Some physiological and biochemical changes (e.g., respiration
and chlorophyll) are almost immediate upon treatment of P.radiata with
autoclaved mucus. This is partly due to the faster uptake of autoclaved
mucus solution which is also less viscous than raw mucus solution,
Raw mucus has an estimated molecular weight of 60,000 - 100,000.
In an aqueous solution, it undergoes slow spontaneous disaggregation
with loss of viscosity to yield dialysable subunits of molecular weight
2,000 - 6,000, which are physiologically active, Rapid disaggregations
are brought about by treatment with moderate concentrations of `NaCl`,
`KCl`, or `CaCl_2`, or by heating, but not with urea, The presence of amylase,
esterase, acid phosphatase, phenoloxidase and proteolytic enzyme
activities in native mucus may be partly responsible for the process
of "natural disaggregation.
The mucus appears to be a fairly homogeneous polysaccharide -
protein complex with properties of both a neutral and an acid polysaccharide. The acidic polysaccharide bears close similarities to mammalian hyaluronic acid in its reactions to histochemical stains. Thus, it reacts with basic dyes at pH 3 - 7, it is orthochromatic in toluidine
blue, red in acridine orange, blue - green in alcian blue, and its
reactions with alcian blue appears to be mediated through its carboxyl
groups, however, it shows high resistance to mammalian hyaluronidase.
Two major polysaccharide - protein complexes, both with physiological
activities, are separated f'rom DEAE - Sephadex, using autoclaved
mucus. The first complex is eluted in 0.1 - 0.4 M `NaCl`, and appears
to be a collageneous type of sulphated glycoprotein, consisting mainly
of fucose, galactose, glucosamine and galacturonic acid. The second
complex is eluted in 0.5 - 0.9 M `NaCl`, and appears to be a conjugate
of sulphated glycoprotein and hyaluronate type of acid mucopolysaccharide.
A total of five hexoses (i.e., rhamnose, fucose, mannose, glucose
and galactose) 1 two hexuronic acids (i.e , glucuronic acid and
galacturonic acid), and two hexosamines (i.e., glucosamine and galactosamine)
are present. The mucus secretion of S.noctilio is compared
with extracellular secretions of microbes which also induce senescence
of their host plants. A brief study of mucus secretions from two
other siricids, i.e., Urocerus gigas and Xeris spectrum, reveals the
presence of protein and carbohydrate, but these secretions do not induce
foliar senescence of P.radiata, and probably indicates a high specificity
of wasp to host tree species.

Item Type: Thesis (PhD)
Keywords: Mucus glands, Pinus radiata, Sirex noctilio
Copyright Information:

Copyright 1977 the author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (Ph.D.) - University of Tasmania, 1977. Includes bibliographical references

Date Deposited: 04 Feb 2015 23:16
Last Modified: 09 Jan 2017 22:09
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