Biomedical Engineering Reference
In-Depth Information
et al. 2004, Li and Yang 2007) and application of jasmonates in non-
mycorrhizal roots results in similar effects (Hause et al. 2007).
3) The root sink position is changed. Mycorrhizal roots require C for the
fungal growth and development. Jasmonates are able to redistribute
the nutrients in mycorrhizal roots and are also able to increase
the root sink capacity resulting in the enhanced production of
carbohydrates in the shoots and their transfer to the roots (Hause
et al. 2007).
4) Improved plant growth by affecting cytokinins levels, which are
known for their effects on cell growth and development (Haberer
and Kieber 2002). For example, application of jasmonates enhanced
the level of cytokinins in potato plants. Also enhanced resistance
to drought and plant pathogens are resulted in mycorrhizal plants
(Auge 2001), which has been attributed to the increased expression
of genes responsible for plant systemic acquired resistance and also
to the production of storage proteins (Miransari 2010a, b).
Using molecular methods it is likely to identify the processes that
are induced by jasmonates during mycorrhization. According to the
transcriptional analysis of mycorrhizal and non-mycorrhizal roots, the
production of genes responsible for different jasmonates functioning has
been recognized. These genes include the ones that are involved in the
production of enzymes producing secondary metabolites or proteins related
to systemic acquired resistance. This is similar to the effect of plant growth
promoting bacteria on enhancing plant growth and systemic acquired
resistance (Pozo et al. 2004).
Salicylic Acid
In addition to the expression of a set of pathogenesis-related (PR)
genes, the signal molecule salicylic acid is also necessary for plant
systematic acquired resistance (Ryals et al. 1996, Lian et al. 2000) and also
mycorrhization (Herrera-Medina et al. 2003). Transgenic plants are very
valuable for the study of such mechanisms including the ones related to
pathogenic and symbiotic processes (Vierheilig et al. 1993, 1995).
Since plant salicylic acid is involved in systemic acquired resistance at
the presence of pathogens (Lian et al. 2000), it may also have a role in the
initiation of AM-plant symbioses (Hause et al. 2007). Exogenous addition of
salicylic acid to rice (
Oryza sative
L.), inoculated with AM fungi decreased
the colonization rate at the beginning of symbiosis, however the formation
of appressoria remained unaffected. The inhibitory effects of salicylic
acid on the growth of AM fungi have also been indicated (Hause et al.
2007). Analysis of the gene,
NahG
, which activates the bacterial enzyme
