Morpho-Anatomical and Physiological Assessments of Cryo-Derived Pineapple Plants (Ananas comosus var. comosus) after Acclimatization

Studies on the morpho-physiology of cryo-derived pineapple plants after acclimatization have been quite limited. Therefore, in the present study, the morpho-anatomical and physiological characteristics of cryo-derived Ananas comosus var. comosus 'MD-2' plants after acclimatization were investigated. Plants obtained from cryopreserved and non-cryopreserved shoot tips, as well as in vitro stock cultures (control), showed similar morphological development (viz. plant height, number of leaves, D leaf length, D leaf width, D leaf area, diameter of stem base, number of roots, plant fresh weight and plant dry weight) to conventionally micropropagated and non-cryopreserved plants. The pineapple plantlets developed efficient anatomical leaf structures that allowed them to adapt to the transition process from in vitro to ex vitro. In all groups of plants, the content of water and chlorophylls (a, a + b, a/b) decreased during the first 15 days of acclimatization and then remained constant until the end of the evaluation. The mesophilic succulence index increased to its maximum value after 15 days, then decreased and remained constant up to 45 days. Although physiological indicators fluctuated during the 45 days of acclimatization, no differences were observed in any of the indicators evaluated when plantlets obtained from cryopreserved shoot tips were compared with controls. The results of the plants from cryopreserved shoot tips show that they switched from C3 to Crassulacean acid metabolism, which denoted metabolic stability during acclimatization.