Direct organ regeneration from apical shoot buds of adult Pinus massoniana Lamb

Abstract

Direct organogenesis is an important technique for plant rapid propagation, which is mainly controlled by the balance of auxin and cytokinin. Pinus massoniana (Lamb.) is a perennial tree species with high application value. Previous studies have shown that direct organ regeneration of young P. massoniana is feasible. However, there are few reports on direct organogenesis of adult P. massoniana. This research studied the effects of apical shoot bud disinfection, plant growth regulators of axillary bud induction, and adventitious root induction of adult P. massoniana. The results showed that the survival rate could reach 50% after removing the outer coat scales and soaking in 500.0 mg L⁻¹ carbendazim solution for 10 min, 75% alcohol for 30 s, and 2.0% NaClO with one drop of Tween for 25 min. The addition of 0.2% plant preservative mixture (PPM) to the medium effectively inhibited contamination of endogenous bacteria, and the survival rate was 90%. The suitable medium for axillary bud induction was Murashige and Skoog (MS) basal medium with 6-benzyl aminopurine (6-BA, 2.0 mg L⁻¹) and indolebutyric acid (IBA, 0.1 mg L⁻¹), and the induction rate reached 15%. A single apical shoot bud induced up to seven axillary buds, and the axillary buds grew vigorously. In addition, 6-BA (2.0 mg L⁻¹) was suitable for needle bundle axillary bud induction. Quarter Douglas-fir cotyledon revised medium (DCR; Gupta and Durzan 1985) with naphthaleneacetic acid (NAA, 0.5 mg L⁻¹) and IBA (0.1 mg L⁻¹) was the most suitable for adventitious root induction. This study preliminarily constructed a regeneration system for direct organogenesis of adult P. massoniana, which was expected to provide key technical support for vegetative propagation of excellent breeding materials for adult P. massoniana.