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ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #146354

Title: APPLICATION OF ECTOMYCORRHIZAL FUNGI IN VEGETATIVE PROPAGATION OF CONIFERS

Author
item NIEMI, KAROLIINA
item Scagel, Carolyn
item HAGGMAN, HELY

Submitted to: Plant Cell Tissue and Organ Culture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2003
Publication Date: 9/24/2003
Citation: Niemi, K., Scagel, C.F., Haggman, H. 2004. Application Of Ecotomycorrhizal Fungi In Vegetative Propagation Of Conifers. v.78: 83-91.

Interpretive Summary: In forestry, vegetative propagation is important for production of selected genotypes and decreasing selection cycles in genetic improvement programs. In vivo cutting production and the in vitro methods of organogenesis and somatic embryogenesis are applicable with conifers. However, with most coniferous species these methods are not yet suitable for commercial application. Economically important conifers in boreal and temperate forests form symbiotic relationships with ectomycorrhizal (ECM) fungi, which increases the fitness of the host tree. Several studies have shown the potential of using ECM fungi in conifer vegetative propagation. Inoculation with specific fungi can enhance root formation and/or subsequent root branching of in vivo cuttings and in vitro adventitious shoots. Germination of somatic embryos and subsequent root growth can also be improved by the use of ECM fungi. In addition, inoculation can increase the trees ability to overcome stress related to transfer from in vitro to ex vitro conditions. Specific interactions between fungal strains and vegetatively propagated tree clones are key factors in the use of ECM fungi in vegetative propagation. This paper reviews our knowledge to date of the use of ECM during vegetative propagation of conifers and describes how multiple rooting factors exist in the interaction between ECM and plants that complicate the predictability of the response to inoculation.

Technical Abstract: In forestry, vegetative propagation is important for production of selected genotypes and decreasing selection cycles in genetic improvement programs. In vivo cutting production and the in vitro methods of organogenesis and somatic embryogenesis are applicable with conifers. However, with most coniferous species these methods are not yet suitable for commercial application. Economically important conifers in boreal and temperate forests form symbiotic relationships with ectomycorrhizal (ECM) fungi, which increases the fitness of the host tree. Several studies have shown the potential of using ECM fungi in conifer vegetative propagation. Inoculation with specific fungi can enhance root formation and/or subsequent root branching of in vivo cuttings and in vitro adventitious shoots. Germination of somatic embryos and subsequent root growth can also be improved by the use of ECM fungi. In addition, inoculation can increase the trees ability to overcome stress related to transfer from in vitro to ex vitro conditions. Specific interactions between fungal strains and vegetatively propagated tree clones are key factors in the use of ECM fungi in vegetative propagation. This indicates that multiple rooting factors exist in this interaction that complicate the predictability of the response to inoculation. Fungal-specific factors that influence rooting responses to inoculation may include plant growth regulator production, modification of rooting environment, and interactions with beneficial microbes. A combination of these factors may act synergistically to result in positive responses in compatible tree genotypes.