The endogenous production and characterization of
the free radical gas NO' in normal dwarf pea (Pisum
sativum) foliage as well as in that of the argentum pea
mutant, has recently been reported by Leshem and
Haramaty [9]. Preliminary experimentation in the
authors' laboratory has also detected the presence of
NO· in sprouts of other legume species - alfalfa and
mesh-bean. Moreover, indirect evidence, based upon
L-arginine -+ L-citrulline conversion and specific
antibody action, has been forthcoming as to the presence
in tobacco of at least one isoform of the NO'-
generating enzyme NOS (E.C.1.l4.13.39) [6]. The
above reports mainly relate to the possible function of
Plant Physiol. Biochem., 0981-9428/98/l1/© Elsevier, Paris
NO' and NOS in environmental and phytopathological
stress situations where they are employed as ethyleneinhibiting
stress-coping mechanisms.
The present research endeavored to extend the
above observations to ascertain possible endogenous
NO' occurrence in a wider spectrum of botanical species
- special attention being given to generative
organs: fruit-bearing species, vegetables and flowers,
of both climacteric and nonclimacteric maturation
habit. For this purpose, we were aided by a newly NO·
specific microprobe, possessing a 200-!1M diameter,
which can be inserted directly into tissue. A further
aim was to monitor changes in NO· content during
maturation and senescence of the above organs and,
more specifically, to ascertain whether immature an