**Preface to "Genetics, Genomics and Biotechnology of Plant Cytoplasmic Organelles"**

Chloroplasts and mitochondria are essential plant organelles involved in many fundamental processes (photosynthesis, energy production, metabolism, cell homeostasis, etc.). They are semi-autonomous organelles; hence, their function is dependent upon cross-talk between nuclear and organelle genetic systems. The Special Issue Book entitled "Genetics, Genomics and Biotechnology of Plant Cytoplasmic Organelles" provides new advances in the sequencing of both mitochondria and chloroplasts' genomes using Next-Generation Sequencing technology in plant species and algae including important crop and tree species, in vitro culture protocol, and identification of a core module of genes involved in plastid development. In particular, the published studies focus on the description of adaptive evolution, elucidate mitochondrial mRNA processing, highlight the effect of domestication process on plastome variability and report the development of molecular markers. A meta-analysis of recently published genome-wide expression studies allowed the identification of novel nuclear genes, involved in the complex and still unrevealed mechanisms at the basis of communication between chloroplast and nucleus (retrograde signalling) during plastid development (biogenic control). Finally, an optimized regeneration protocol useful in plastid transformation of recalcitrant species, such as sugarcane, has been reported. We would like to thank to all the authors and their contributions as well as the reviewers for their constructive suggestions. Further, the Plants MDPI team and, particularly, Hinata Fang deserve our thanks for their support.

The editors declare no conflict of interest.

**Nunzia Scotti, Rachele Tamburino** *Editors*
