Arbuscular mycorrhiza

Most plants in natural habitats form associations with mycorrhizae. Arbuscular mycorrhizal fungi (AMF) are obligate symbionts, and infection of plant roots exerts a metabolic load on the host plant (Reid, 1990). During infection and... 

Root products, as defined by Uren and Reisenauer (17), represent a wide range of compounds. Only secretions are deemed to have a direct and immediate functional role in the rhizosphere. Carbon dioxide, although labeled an excretion, may play a role in rhizosphere processes such as hyphal elongation of vesicular-arbuscular mycorrhiza (39). Also, root-derived CO2 may have an effect on nonphotosynthetic fixation of CO2 by roots subject to P deficiency and thus contribute to exudation of large amounts of citrate and malate, as observed in white lupins (40). The amounts utilized are very small and, in any case, are extremely difficult to distinguish from endogenous CO2 derived from soil and rhizosphere respiration. 

S. M. Schwab, J. A. Menge, and R. T. Leonard, Quantitative and qualitative effects of phosphorus on extracts and exudates of sudangrass roots in relation to vesicular-arbuscular mycorrhiza formation. Plant Physiol. 73 761 (1983). 

M. G. Nair, G. R. Safir, and J. O. Siqueira, Isolation and identification of vascular-arbuscular mycorrhiza-stimulatory compounds from clover (Trifolium repens) roots. AppL Environ. Microbiol. 57 434 (1991). 

R. C. Snellgrove, W. E. Splitstoesser, D. B. Strubket, and P. B. Tinker. The distribution of carbon and the demand of the fungal symbiont in leek plants with vesicular-arbuscular mycorrhizas. New Phytologist 69 15 (1982). 

N. S. Bolan, A. D. Robson, and N. J. Barrow, Effects of vesicular-arbuscular mycorrhiza on the availability of iron phosphates to plants. Plant and Soil 99 40l (1987). 

R. G. Linderman, Vesicular-arbuscular mycorrhizae and soil microbial interactions, Mycorrhizae in Sustainable Agriculture (G. J. Bethlenfalvay and R. G. Linderman, eds.), American Society of Agronomy, Madison, Wisconsin, 1992, p. 45. 

D. Werner, S. Bernard, E. Gorge, A. Jacobi, R. Rape, K. Kosch, M. Pamiske, S. Schenk, P. Schmidt, and W. Streit, Competitiveness and communication for effective inoculation by Rhizohium, Bradyrhizohium and vesicular-arbuscular mycorrhiza fungi. Experientia. 50 884 (1994). 

Arbuscular mycorrhizae Many plant species, including representatives of bryophytes, gymnosperms, and many angio-sperms Glomales Appressoria. inter- and intracellular hyphae, coils, arbuscules, vesicles... 

S. Gianinazzi and H. Schuepp, Impact of arbuscular mycorrhizas on sustainable agriculture and natural ecosystems, Birkhauser Verlag, Basel, 1994. 

R. L. Peterson and P. Bonfante, Comparative structure of vesicular-arbuscular mycorrhizas and ectomycorrhizas. Plant Soil 159 19 (1994). 

There are three distinct types of mycorrhizae, but the vesicular-arbuscular mycorrhiza is found on more plant species than... 

FIGURE 19.7 Representatives of apocarotenoid derived signaling molecules associated with arbuscular mycorrhiza formation. 

Fester, T., W. Maier et al. (1999). Accumulation of secondary compounds in barley and wheat roots in response to inoculation with an arbuscular mycorrhizal fungus and co-inoculation with rhizosphere bacteria. Mycorrhiza 8(5) 241-246. 

Strack, D., T. Fester et al. (2003). Arbuscular mycorrhiza Biological, chemical, and molecular aspects. J. Chem. Ecol. 29(9) 1955-1979. 

Vierheilig, H., H. Gagnon et al. (2000). Accumulation of cyclohexenone derivatives in barley, wheat and maize roots in response to inoculation with different arbuscular mycorrhizal fungi. Mycorrhiza 9(5) 291-293. 

Rillig MC (2004) Arbuscular mycorrhizae, glomalin, and soil aggregation. Can J Soil Sci 84 355-363... 

Mycorrhiza have been shown to be very important for P uptake (Bolan 1991 van der Heijden et al. 2006). In wheat, the arbuscular mycorrhizal colonization decreased with increasing soil P. It was reduced from 60% of root length colonized at 10 mg P kg-1 soil to 10% at 27 mg P kg-1 soil (Covacevich et al. 2007). This was independent of shoot P contents. 

Klironomos JN, McCune J, Hart M, Neville J (2000) The influence of arbuscular mycorrhizae on the relationship between plant diversity and productivity. Ecol Lett 3 137-141 Lajtha K, Harrison AF (1995) Strategies of phosphorus acquisition and conservation by plant species and communities. In Hessen H (ed) Phosphorus in the global environment. Wiley, Chichester, UK, pp 140-147... 

Schreiner PR, Ivors KL, Pinkerton JN (2001) Soil solarization reduces arbuscular mycorrhizal fungi as a consequence of weed suppression. Mycorrhiza 11 273-277. doi 10.1007/... 

Wang K, Zhao Z, Occurrence of arbuscular mycorrhizas and dark septate endophytes in hydrophytes from lakes and streams in southwest China, Inti Rev Hydrobiol 91 29-37, 2006. 

Zhao X et ai, Effects of arbuscular mycorrhiza on camptothecin content in Camptotheca acuminata seecUings, Shengtai Xuebao 26 1057—1062, 2006. 

Wyss P et al, Vesicular-arbuscular mycorrhizas of wild-type soybean and non-nodulating mutants with Glomus mosseae contain symbiosis-specific polypeptides (mycorrhizins), immunologically cross-reactive with nodulins, Planta 182 22— 26, 1990. 

Mandelbaum Cl, Piche Y,The role of root exudates in arbuscular mycorrhiza initiation, in Mukerji KG, Chamola BP, Singh J (eds.), Mycorrhizal Biology Kluwer Academic/Plenum Publishers, New York, 153-172, 2000. 

Several authors have obtained circumstantial evidence that allelopathic compounds reduce mycorrhizae formation (20-23). Kovacic and associates ( ) have shown that understory plants in a live ponderosa pine stand are largely nonmycorrhiza-forming species. They hypothesized that this was due to inhibition of the vesicular-arbuscular mycorrhiza necessary for the growth of herbaceous mycorrhizal plants, under living pines. They demonstrated that more mycorrhizal plants occurred under dead pines, bioassay plants formed mycorrhizae in soils beneath dead pines but not in soil beneath live pines, and mycorrhizal inoculum appeared to be absent from the live pine stand. 

Rhlid, R.B. et al., Isolation and identification of flavonoids from Ri T-DNA-transformed roots (Daucus carotd) and their significance in vesicular-arbuscular mycorrhiza, Phytochemistry, 33, 1369, 1993. 

Akiyama, K., Matsuoka, H., and Hayashi, H., Isolation and identification of a phosphate deficiency-induced C-glycosylflavonoid that stimulates arbuscular mycorrhiza formation in melon roots. Mol Plant-Microbe Interact., 15, 334, 2002. 

---