Global DNA Methylation Levels During the Development of Nodule Cluster Cultures and Assessment of Genetic Fidelity of In Vitro-Regenerated Pineapple Plants (Ananas comosus var. comosus)

Pineapple presents a significant portion of the global fruit market. Recently, a micropropagation protocol was established based on nodule cluster cultures (NC), which showed high regenerative efficiency. Aiming to expand the understanding of gene regulation in this protocol, global DNA methylation levels (GDML) and fresh mass increase ratio (FMIR) during NC multiplication and differentiation to microshoots were evaluated after 0, 9, 18, 27, and 36 days in culture. In addition, genetic fidelity of randomly chosen regenerated plants was analyzed by means of amplified fragment length polymorphism (AFLP), flow cytometric analysis of ploidy level, as well as observation of phenotypic features. An association between GDML and the density of new shoot apical meristems formed in cultures was observed, which was, in turn, related to FMIR and the age of each subculture. The analysis by means of AFLP and DNA ploidy level, as well as phenotypic observations indicated the homogeneity of regenerated plantlets.