Biomedical Engineering Reference
In-Depth Information
are similar to the effects of IAA on plant roots. Hence, the role of IAA
in mycorrhizal symbiosis has been suggested (Ludwig-Muller 2000). In
addition, Gryndler et al. (1998) found that IAA is able to enhance the
growth of
Glomus fi stulosum
.
Strigolactones can regulate auxin transport in the plant through
affecting auxin carriers (Koltai et al. 2010) or through affecting the secondary
messengers, which are active in auxin signaling (Ferguson and Beveridge
2009, Brewer et al. 2009). This suggests that auxin may indirectly affect
the symbiotic level as it is infl uenced by strigolactones. In other words,
the interactive effects of strigolactones and auxin may affect plant growth
through affecting the symbiont activities. Among different factors affecting
the symbiotic effi ciency is root growth and development, which is affected
by the plant hormone strigolactones and their interaction with different
plant hormones including auxin (Teale et al. 2008).
Jasmonic Acid
Jasmonic acid and its derivatives (signals derived from lipid molecules) are
plant hormones regulating plant growth as well as plant response under
stress. Jasmonates and ethylene, which are produced in a transduction
pathway, are parts of plant systemic acquired resistance and adjust
plant interactions with microorganisms (Pozo et al 2004, Mabood
and Smith 2005, Van Wees et al. 2008, Van der Ent et al. 2009). Hence
jasmonates, regulate the expression of genes involved in deactivating
proteinase, production of phytoalexin and proteins, vegetative growth
and storage and also production of thionins, which are responsible for
plant resistance to different stresses (Devoto and Turner 2005, Lorenzo
and Solano 2005).
The level of jasmonates increases in mycorrhizal roots of plants
including
Hordeum vulgare
(Hause et al. 2002),
Cucumis sativus
(Vierheilig
and Piche 2002),
Medicago trancatula
(Stumpe et al. 2005) and
Glycine max
(Meixner et al. 2005). The increased rates in mycorrhizal plants differ among
different plants, for example in
M. trancatula
the increase was between two
to three times relative to non-mycorrhizal plants (Stumpe et al. 2005), while
for
H. vulgare
and
C. sativus
the related increases were up to 5 and 14 fold,
respectively (Hause et al. 2002, Vierheilig and Piche 2002). Such increase
may positively affect the process of AM symbiosis.
The activation of AM symbiosis by jasmonic acid is concentration
dependent and while concentration of 5 µM can stimulate and enhance root
colonization, higher concentrations of 0.05-5 mM may adversely affects the
symbiosis process (Ludwig-Muller et al. 2000). Recent research has also
indicated that higher amount of jasmonic acid is found in mycorrhizal roots
relative to non-mycorrhizal roots (Hause et al. 2002, Meixner et al. 2005).
