Biomedical Engineering Reference
In-Depth Information
that strigolactones can signifi cantly affect the process of AM symbiosis and
hence the ecosystem effi ciency.
Formononetin
The signal molecules formononetin are able to enhance AM symbiosis
through increasing sporulation (Nair et al. 1997, Davies et al. 1999, 2005a).
Hence, this can enhance the inoculating potential of AM fungi and can be
of economical signifi cance as less amount of AM fungal inoculum would
be required for effi cient inoculation. Sporulation is affected by different
parameters including AM species, climatic parameters and soil properties
(Davies et al., 2005a).
In a greenhouse study Davies et al. (1999) found that formononetin
enhanced AM and plant growth parameters including extraradical hyphal
growth, net photosynthesis, stomatal activity and shoot growth in Russet
Norkotah potatoes. In another greenhouse study formononetin increased
the formation of extraradical hyphal development (but not the total
inoculation of plant roots, which does not always result in enhanced plant
growth, Davies et al. 2005a) and potato tuber yield (Davies et al. 2005b).
Other Plant Hormones
Exchange of signal molecules between the two partners is necessary for
the benefi cial initiation of mycorrhizal symbiosis (Harrison 1999, 2005). It
is believed that plant hormones, including cytokinins, gibberellins, ABA,
IAA and jasmonic acid are involved in some of these mechanisms, however
their exact roles in the symbiosis between the two partners is still not
understood (Ludwig-Muller 2000, Hause et al. 2007). Nevertheless, the role
of ABA and JA has been more clearly indicated for the symbiosis process,
relative to the other plant hormones (Isayenkov et al. 2005, Herrera-
Medina et al. 2007). The indication of plant hormone involvement in the
AM-plant symbiosis is based on the alteration of plant hormones during
the establishment of symbiosis and also on the exogenous application of
plant hormones (Bothe et al. 1994, Hause et al. 2007). Investigating the
effects of plant hormones on the AM symbiosis process can elucidate the
related mechanisms and also indicate more details regarding the way by
which plant hormones can affect plant growth.
Cytokinins
The accumulation of cytokinins in mycorrhizal plants is higher than non-
mycorrhizal plants in both shoots and roots (van Rhijn 1997, Hause et al.
2007) and this alteration usually is related to the late stage of symbiosis
