Micropropagation of Catasetum integerrimum Hook (Orchidaceae) through seed germination and direct shoot regeneration from pseudobulbs and roots

Abstract

Catasetum integerrimum is an orchid used in Mexican traditional medicine, which is overexploited due to its ornamental and medicinal properties. In this scenario, conservation strategies are mandatory to protect wild populations from this valuable orchid. The aim of the present study was to establish a micropropagation protocol by direct organogenesis, as a tool for Catasetum integerrimum production and conservation. Seeds from a mature capsule were cultivated in a Murashige and Skoog basal medium. Then, 6-mo-old vitroplants were transplanted into treatments fortified with 6-bencilaminopurin (BAP) or indole-3-acetic acid (IAA) to induce plant development. Treatment fortified with 2.5 mg L⁻¹ BAP in combination with 5.0 mg L⁻¹ IAA developed 5.73 ± 0.45 shoots per explant and 5.84 ± 0.48 leaves per shoot. For the rooting process, the best treatment was 2.5 mg L⁻¹ IAA, which developed 11.20 ± 0.28 roots with a 13.20 ± 0.28-cm root length. C. integerrimum vitroplants were used as a source of leaves, roots, and pseudobulbs for the induction of direct organogenesis. Leaf explants did not induce any morphogenic response. Pseudobulb explants had the best response when developing 1 shoot per explant with 5.50 ± 0.18 leaves per shoot and 4.37 ± 0.37 roots per explant with a 4.88 ± 0.20-cm root length. For the acclimatization stage, a survival rate of over 90% was achieved. The results obtained prove the efficacy of the micropropagation method, which contributes significantly to the conservation of this orchid, preserving its wild populations from indiscriminate collection.