Enhancing Avocado Production through Optimized In Vitro Propagation Techniques

Abstract

Advancements in plant tissue culture have significantly enhanced the production of many plant species. However, avocados (Persea americana Mill.), classified as woody plants, have been shown to be highly recalcitrant to in vitro conditions. They possess several challenges, especially contamination and oxidation, which make successful propagation difficult. While some studies have successfully improved protocols for specific avocado cultivars, many others still need further optimization. Through in vitro propagation techniques, this study aims to optimize superficial sterilization techniques and best media formulations to produce true-to-type and virus-free avocado plantlets. Therefore, a total of 2,508 meristems and 1,701 axillary buds from three avocado cultivars: Hass, Lamb Hass, and Ettinger, were collected from an orchard in Lebanon and cultured on 24 different media. Initial trials showed high levels of contamination and oxidation. To address this problem, different sterilization protocols were tested on a selected Murashige and Skoog (MS) medium supplemented with 1.5 mg/L benzyl aminopurine (BAP) on both orchard-derived explants and greenhouse-derived explants. Results show that greenhouse-derived explants performed better after sterilization, especially with 40% Clorox. At the same time, none of the sterilization protocols reduced contamination in the orchard-derived axillary buds, while some effectively eliminated contamination in orchard-derived meristems. Among the 24 tested media, Woody Plant medium (WPM) with 0.5 mg/L BAP provided the best result, with improved survival and reduced oxidation. Antioxidant treatments (ascorbic acid + PVP and PVP alone) showed a limited effect. Although complete regeneration was not achieved, early callus formation and slight shoot elongation were observed in some treatments. Though oxidation remained an issue for other media, further refinement is needed to overcome this challenge and improve the efficiency of tissue culture techniques for avocado propagation.