Propagation of Ornamental Plants
12(3): 139-147, 2012
PISOLITHUS ARHIZUS (SCOP.) RAUSCHERT IMPROVES GROWTH OF ADVENTITIOUS ROOTS AND ACCLIMATIZATION OF IN VITRO REGENERATED PLANTLETS OF PINUS PINEA L.
Carla Ragonezi1,3*, Ana Teresa Caldeira4,5, Maria do Rosário Martins3,4, Luís Silva Dias2, Celeste Santos-Silva2,3, Elsa Ganhão2, Otília Miralto2, Isabel Pereira3,7,
Rogério Louro3, Krystyna Klimaszewska6, and Amely Zavattieri2,3
1Plant Breeding and Biotechnology Laboratory, University of Évora, Largo dos Colegiais 2, 7002-554 Évora, Portugal, *Fax: + 351 266760914, *E-mail: email@example.com
2 Department of Biology, University of Évora, Largo dos Colegiais 2, 7002-554 Évora, Portugal
3 Institute of Mediterranean Agricultural and Environmental Sciences (ICAAM), University of Évora, Largo dos Colegiais 2, 7002-554 Évora, Portugal
4 Department of Chemistry, University of Évora, Largo dos Colegiais 2, 7002-554 Évora, Portugal
5 CQE, University of Évora, St. Romão Ramalho 59, 7000-671 Évora, Portugal
6 Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., P. O. Box 10380, Stn. Sainte-Foy, Québec, QC G1V 4C7, Canada
7 Laboratory of Botany, University of Évora, Largo dos Colegiais 2, 7002-554 Évora, Portugal
Stone pine (Pinus pinea L.) is an economically important forest tree in the Mediterranean region and has been the target of breeding and selection through micropropagation mainly for its ecological and ornamental aspects. A crucial step in micropropagation is adventitious rooting of microshoots, which often is highly inefficient in most conifer species including stone pine. Hence, we conducted in vitro co-culture of Pinus pinea microshoots with the ectomycorrhizal fungus Pisolithus arhizus (isolated from natural stands) in order to promote adventitious root growth and plant survival during acclimatization. Significant differences were found in the number of branches, in the number of roots plus branches, in total length of roots, in total length of roots plus branches, in average root length and in the length of the longest root in inoculated plants during in vitro rooting compared with non-inoculated plants. The roots of inoculated plants also grew better in vermiculite and during acclimatization in a mixed substrate compared with roots of control plants resulting in the development of vigorous root system. Overall, mycorrhizal inoculation increased the survival rate of the regenerated pine.
Key words: co-culture, in vitro mycorrhization, micropropagation, root system.