In Vitro Regeneration through Direct Organogenesis from Protocorms of Oncidium tigrinum Llave & Lex. (Orchidaceae), an Endemic and Threatened Mexican Species

Abstract

A protocol for in vitro propagation from protocorms of Oncidium tigrinum Llave & Lex., a threatened species distributed in Mexico and highly appreciated as an ornamental, was developed. Two different explants, entire protocorms and longitudinal halves of protocorms, were used. In addition, the effect of two different culture media, Murashige and Skoog (MS) and modified Knudson (KCm), supplemented with N6-benzyladenine (BA) (0, 0.5, 1, 2, 3, and 5 mg·L−1) and/or α-naphthaleneacetic acid (NAA) at 0, 0.1, and 0.5 mg·L−1 was investigated. Adventitious shoot formation by direct organogenesis was obtained in all treatments; in some cases, the formation of protocorm-like bodies was induced. Shoot formation was greater for entire protocorms; the best treatment was MS medium containing at BA 1 to 2 mg·L−1 in combination with at NAA 0.1 mg·L−1. The average height of shoots was three times greater in MS medium than in KCm medium. Subculturing individual shoots in MS medium without plant growth regulators, but with 1 g·L−1 activated charcoal, allowed further development and rooting. An ex vitro survival rate of almost 100% was achieved. This study represents a comprehensive application for propagation, conservation, and sustainable use of this valuable natural resource.