Micropropagation of Pinus massoniana and mycorrhiza formation in vitro

Abstract

A protocol was developed for the micropropagation of Pinus massoniana and mycorrhiza formation on rooted microshoots. Seedling explants were first cultured on Gresshoff and Doy (GD) medium supplemented with 6-benzyladenine (BA) alone or in combination with α-napthaleneacetic acid (NAA) to stimulate the formation of intercotyledonary axillary buds. The frequency of axillary bud induction was up to 97% on medium supplemented with 4.0 mg l−1 BA and 0. 2 mg l−1 NAA, and the average number of buds per explant reached up to 5.5 on medium with 4.0 mg l−1 BA and 0.1 mg l−1 NAA. Axillary buds elongated rapidly after being transferred to half-strength GD medium containing activated charcoal (0.1% w/v). Shoot proliferation was achieved by cutting elongated shoots into stem segments and subculturing on GD medium containing 2 mg l−1 BA and 0.2 mg l−1 NAA. Root primordia were induced in 82% of shoots when transferred to half-strength GD medium containing 0.2 mg l−1 NAA. Root elongation was achieved in a hormone-free GD agar medium or a perlite substrate. Rooted plantlets were inoculated with the mycelium of ectomycorrhizal fungus Pisolithus tinctorius and the formation of ectomycorrhiza-like structures was achieved in vitro.