Abstract

In vitro cultivation is a key tool for propagation, conservation, and scientific research. While in vitro germination protocols are typically standardized for many species, they can be optimized through small modifications that prove highly effective. The extremophile species Colobanthus quitensis has been proposed as a model for stress research, and its distribution in Antarctica faces increasing threats due to tourism and scientific activities. Ex situ conservation in germplasm banks offers a promising alternative; however, the low in vitro germination rate of these populations limits its application, highlighting the need to optimize the existing germination protocol. This study addressed two key questions: (1) What is the optimal composition of the culture medium to stimulate C. quitensis germination? and (2) Which priming and dormancy-breaking treatment is most effective for Antarctic seed populations? Through four experiments, the in vitro germination protocol was optimized, followed by a fifth experiment to evaluate scarification methods and develop a specific protocol for Antarctic populations. The results showed that C. quitensis can germinate in an in vitro medium composed of water, 0.7% agar, and pH 5.5. However, the highest germination and seedling development were achieved with seeds treated for 24 hours with 5% potassium chloride, cultivated in 25% Murashige and Skoog medium, without sucrose, with 0.7% agar, and pH 5.5. For Antarctic populations, in addition to halo-priming, manual testa breaking with a scalpel was necessary to enable germination. The resulting protocols are efficient, cost-effective, and easy to implement for this and other commercial species with similar characteristics.