S04 - Session O4 - Molecular insights to understand micropropagation - Regulatory role of ncRNAs networks in the expression and maintenance of the embryogenic competence in Solanum betaceum Cav. Calli

Authors: Daniela Cordeiro *, Jorge Canhoto, Sandra Correia

RNA species with no protein-coding capacity, including micro and long non-coding RNAs (miRNAs and lncRNAs), are being increasingly reported as essential regulators in a wide diversity of biological processes by controlling gene expression. However, their role in plant somatic embryogenesis (SE) regulation is far from being fully understood. SE is a developmental pathway by which somatic plant cells reprogram, acquire totipotency and embark into somatic embryo formation. Since it is a valuable tool for the large-scale micropropagation of numerous economically important species, there is a great interest in the analysis of the gene regulatory networks underlying it. As a two-step SE process, long-term maintainable by subculturing induced embryogenic calli, the SE in tamarillo (Solanum betaceum Cav.) represents a good system to study the molecular mechanisms involved in the embryogenic competence acquisition, expression and maintenance. Thus, high-throughput RNA sequencing approaches were used to analyse the ncRNA-mediated regulation of the embryogenic ability in tamarillo SE-induced cell lines with different embryogenic competencies. Small RNAs libraries, including miRNAs, were prepared and analysed using TruSeq Small RNA Library Preparation for Illumina sequencing and lncRNAs libraries using the Direct cDNA Sequencing Kit from Oxford Nanopore Technologies. Differential ncRNAs expression profiles were revealed between embryogenic, non-embryogenic and callus that lost its embryogenic potential. After data validation by qPCR, it was found that specific miRNA-target regulatory nodes may be involved in the acquisition and expression of embryogenic competence, whereas others seem to be more related to the loss of that capacity during repetitive subcultures. More experiments are being carried out on the functional analysis of these ncRNAs to better understand the loss of embryogenic ability through subcultures. Nevertheless, the results so far obtained pointed-out regulatory roles of ncRNAs in the plant regeneration process giving insight to improve this process in economically relevant crops.