The Salvia divinorum Research and Information Center - Shroomery

Salvia Divinorum
In classical genetic
self-incompatability
systems, the site of
pollen tube inhibition
is on the stigma
surface or somewhere
in the style. A pollen
grain may fail to
germinate, or
produces a tube that
grows abnormally
and is soon occluded
by callose, or
produces a tube that is eventually rejected by the transmitting tissue of
the style (Heslop-Harrison 1975). Although this type of active
inhibition of the pollen tube may not be the only form of genetic mate
discrimination in plants (Mulcahy & Mulcahy 1983), the best
understood self-rejection systems (oppositional systems) do involve
observable changes (e.g., swelling) in the growing tip of the pollen
tube. No such abnormalities were observed for S. Divinorum, and no
occlusions were found anywhere in the style. A barrier to seed set is
apparently encountered after pollen tubes reach the ovary, at some
point between the time the tube enters the micropyle of the ovule and
the early development of the embryo. Since calyces often abscise while
the included nutlets are developing, post-zygotic embryo abortion or
endosperm failure is probable. Whether this is due to inbreeding
depression, hybridity, or a late acting (delayed) self-incompatability
reaction is difficult to know with certainty. The latter is unlikely,
especially because gametogenesis and other stages of the life cycle are
also irregular, and one would think the various aberrations have a
common cause. Inbreeding depression is often the fate of taxa that
become closely associated with man, and could potentially cause the
observed irregularities.
http://www.sabia.com/salvia/my_html/fertility1.html (4 of 5) [04.09.01 10:52:41]