Field performance and (epi)genetic profile of plantain (Musa AAB) clone ‘CEMSA ¾’ plants micropropagated by temporary immersion systems

Abstract

Use of meta-topolin (mT) [6-(3-hydroxybenzylamino) purine] to scale up the plantain clone ‘CEMSA ¾’ in temporary immersion systems (TIS), when compared with conventional micropropagation protocols, has been shown to improve production and quality of microplants. To evaluate the impact of those innovations on plant field performance, in vitro plants of ‘CEMSA ¾’ were subjected to either an additional multiplication cycle using TIS or semi-solid medium (SS) in the presence of 4.44μM mT or N6-benzyladenine (BA). Growth and yield components in the microplants grown in field – plant crop – and in the developed plants of the following field generation – first ratoon – were evaluated. Also (epi)genomic traits were studied by flow cytometry, fluorimetry-based AFLP and HPLC analyses of global genomic DNA methylation. Neither in vitro microprogation systems – TIS and SS – nor cytokinins – mT and BA – had any factorial effect on yield productivity of the plant crop. In the first ratoon, significant differences in yield appeared, with TIS-BA plants being more productive than those generated from TIS-mT. For most of the measured variables, the plant crop had higher values than the first ratoon, but true-to-type and each off-type phenotype of the plant crop was always inherited by their corresponding offspring of the first ratoon. The proportion of true-to-type plants was higher for SS-BA and TIS-mT culture conditions. Irrespective of micropropagation protocol and phenotype, in the plant crop, average genomic DNA content was maintained and global genomic methylation levels were similar. Nevertheless, dwarf individuals showed more AFLP polymorphisms with respect to mother plants than the rest of the micropropagated plants, and a dwarfism-related AFLP marker is proposed. On the basis of the results obtained and previous reports, the innovative TIS-mT protocol was deemed to be the most suitable plantain multiplication technique among those tested.