关键词: 油桐, 叶柄, 愈伤组织, 不定芽, 再生体系

Abstract: INTRODUCTION Tung tree (Vernicia fordii) represents a significant woody species utilized for industrial oil production. Existing tissue culture methodologies predominantly rely on sterile seedling-derived explants. However, the complex growth environment of field-grown adult trees presents significant challenges for explant sterilization, leading to low efficiency in callus induction and differentiation, which severely limits the micropropagation of elite cultivars. RATIONAL In this study, petioles collected from mature (four years old) field-grown tung trees were used as explants to investigate the effects of different plant growth regulators on callus induction, differentiation, seedling strengthening, and rooting. Key technical barriers including sterilization, differentiation, and seedling growth were successfully overcome, establishing a stable in vitro regeneration system from petiole explants. The results showed that the optimal medium for callus induction was 1/2MS supplemented with 3.0 mg·L?1 6-BA and 0.05 mg·L?1 IAA, achieving an induction rate of 100%. The best medium for adventitious bud differentiation was 1/2MS containing 3.0 mg·L?1 6-BA, 0.05 mg·L?1 IAA, and 0.1 mg·L?1 GA?, with a differentiation rate of 70.00%. The most effective medium for promoting robust seedling growth was 1/2MS with 0.5 mg·L?1 6-BA, 0.025 mg·L?1 IBA, and 0.1 mg·L?1 GA?, yielding a success rate of 87.00%. For rooting, the optimal medium was 1/2MS with 0.5 mg·L?1 IBA, resulting in a rooting rate of 70.00%. After acclimatization, plantlets transplanted into a substrate mixture of nutrient soil: perlite: vermiculite (2:1:1, v/v/v) exhibited vigorous growth. The established in vitro regeneration system provides a reliable technical foundation for the conservation of V. fordii germplasm resources and the rapid propagation of elite cultivars. RESULTS The results showed that the optimal medium for callus induction was half-strength Murashige and Skoog (1/2 MS) medium supplemented with 3.0 mg·L?1 6-Benzylaminopurine (6-BA) and 0.05 mg·L?1 Indole-3-Acetic Acid (IAA), achieving a callus induction rate of 100%. The optimal medium for shoot differentiation comprised 1/2 MS supplemented with 3.0 mg·L?1 6-BA, 0.05 mg·L?1 IAA, and 0.1 mg·L?1 Gibberellic Acid (GA3), which resulted in a differentiation rate of 70.00%. For promoting plumule elongation and robust seedling development, the most efficacious medium was 1/2 MS supplemented with 0.5 mg·L?1 6-BA, 0.025 mg·L?1 IBA, and 0.1 mg·L?1 GA3, which resulted in an 87.00% success rate in promoting robust seedling elongation. Furthermore, the optimal medium for root induction was 1/2 MS containing 0.5 mg·L?1 IBA, achieving a rooting frequency of 90.00%. Following the transplantation of culture-bottle seedlings into a substrate consisting of nutrient soil, perlite, and vermiculite in a 2:1:1 ratio, the tissue culture seedlings demonstrated optimal growth performance. CONCLUSION The established in vitro regeneration system provides a reliable technical foundation for the conservation of tung tree germplasm resources and the rapid propagation of elite cultivars.

Key words: Vernicia fordii, petioles, callus, adventitious shoots, regenerations system