JXB Advance Access originally published online on November 21, 2006
Journal of Experimental Botany 2007 58(3):391-401; doi:10.1093/jxb/erl209
RESEARCH PAPER |
Suillus variegatus causes significant changes in the content of individual polyamines and flavonoids in Scots pine seedlings during mycorrhiza formation in vitro
1Department of Applied Biology, University of Helsinki, PO Box 27, 00014 University of Helsinki, Finland
2Department of Biology, University of Joensuu, PO Box 111, 80101 Joensuu, Finland
3Department of Biology, University of Oulu, PO Box 3000, 90014 University of Oulu, Finland
4Finnish Forest Research Institute, Parkano Research Unit, 39700 Parkano, Finland
* To whom correspondence should be addressed. E-mail: Karoliina.Niemi{at}helsinki.fi
Changes in the concentrations of individual flavonoids and polyamines (PAs) in Scots pine (Pinus sylvestris L.) cotyledonary seedlings were studied during the establishment of an ectomycorrhizal (ECM) symbiosis with two Suillus variegatus strains in vitro. Both flavonoids and PAs were analysed after 3, 7, and 14 d in dual culture, and changes in concentrations were compared with growth of the seedlings. Both S. variegatus strains caused similar responses in Scots pine seedlings. Free putrescine accumulated immediately but only transiently after inoculation. This was followed by continuous accumulation of PA conjugates in needles and stems, and free spermidine and spermine in roots, which was accompanied by mycorrhiza formation and improved growth. The fungi induced lateral root formation and main root and primary needle elongation. Inoculation caused no qualitative changes in flavonoid composition, while quantitative changes in flavonols, catechins, and condensed tannins were observed in shoots during mycorrhiza formation. These results indicate that in this in vitro system conjugated PAs and specific flavonoids, generally related to the plant's defence reactions, did not play a major role in the regulation of the establishment of the ectomycorrhizal (ECM) symbiosis in Scots pine roots. The results also clearly show that positive growth responses in shoots and roots due to S. variegatus were supported by different and highly specific changes in the synthesis of both primary and secondary metabolites in these parts of the seedling.
Key words: Ectomycorrhizas, flavonoids, Pinus sylvestris, polyamines, Suillus variegatus
Received 29 June 2006; Revised 12 September 2006 Accepted 19 September 2006