Biomedical Engineering Reference
In-Depth Information
AM-plant symbiosis and hence more enhanced ecosystem production.
Most of the mycorrhizal signaling details that have been indicated so far
are related to the legumes with calcium as one of the regulators (Gutjahr et
al. 2008, Oldroyd et al. 2009). However, it has been indicated very recently
that steroids may also act as signal molecules in mycorrhizal symbiosis
(Bucher 2010, Kuhn et al. 2010). This review article indicates some more
details regarding signaling in mycorrhizal symbiosis with some future
research ideas.
THE MOLECULAR ASPECT OF AM-PLANT SYMBIOSIS
Root morphology is changed during the AM-plant symbiosis where
specifi c physiological processes are developed. Accordingly, it is suggested
that there are specifi c signal transduction pathways, resulting in the
induction of AM genes and regulation of pathogenic interactions (Hause
and Fester 2005). It is somehow similar to the process of signal exchange
between rhizobium bacteria and legume plants (Miransari et al. 2006,
Miransari and Smith 2007, 2008, 2009, Garg and Geetanjali
2009, Li et al.
2009).
There are different molecular pathways controlling the AM-plant
symbiosis. After the recognition of the host plant, the fungal spore will start
functioning, resulting in its germination and subsequent growth of hypha
into the plant root. These processes involve the alteration of transduction
pathways in both symbionts, eventually resulting in the expression of
the related genes in both symbionts for the continuation of the symbiosis
between the two partners.
It has also been verifi ed that there are identical genes, expressed during
both the AM-plant- and rhizobium-legumes-symbioses (Manthey et al.
2004). These genes have been identifi ed by the discrepant or subtractive
hybridization belonging to the
ENOD
(early nodulin genes) library
(Albrecht et al. 1998, Boisson-Dernier et al. 2005). In the following the signal
molecules, which are mostly plant hormones, affecting AM symbiosis are
reviewed.
AM FUNGI AND SIGNAL MOLECULES
Strigolactones
Researchers have used molecular techniques for the identifi cation of
the signal molecules
(Table 1)
produced by the host plant affecting AM
symbiosis. Akiyama and Hayashi (2006) recently identifi ed the signal
molecules strigolactones (5 deoxy-strigol), belonging to a new class of
