Plant Cellular and Molecular Biotechnology: Following Mariotti’s Steps

Abstract

This review is dedicated to the memory of Prof. Domenico Mariotti, who significantly contributed to establishing the Italian research community in Agricultural Genetics and carried out the first experiments of Agrobacterium-mediated plant genetic transformation and regeneration in Italy during the 1980s. Following his scientific interests as guiding principles, this review summarizes the recent advances obtained in plant biotechnology and fundamental research aiming to: (i) Exploit in vitro plant cell and tissue cultures to induce genetic variability and to produce useful metabolites; (ii) gain new insights into the biochemical function of Agrobacterium rhizogenes rol genes and their application to metabolite production, fruit tree transformation, and reverse genetics; (iii) improve genetic transformation in legume species, most of them recalcitrant to regeneration; (iv) untangle the potential of KNOTTED1-like homeobox (KNOX) transcription factors in plant morphogenesis as key regulators of hormonal homeostasis; and (v) elucidate the molecular mechanisms of the transition from juvenility to the adult phase in Prunus tree species.

Plant Development and Organogenesis: From Basic Principles to Applied Research

“…In the review from De Paolis et al [1] two sections are dedicated to the “hairy root” syndrome induced by Agrobacterium rhizogenes , characterized by the emergence of adventitious roots at the wound site of infected plants, and application of A. rhizogenes rooting locus ( rol ) genes to fruit tree propagation and transformation. How these rol genes act to highjack somatic plant cells to induce root meristem initiation and maintain indeterminate adventitious root growth is still a fascinating “enigma” after more than 30 years since their identification.…”

“…How these rol genes act to highjack somatic plant cells to induce root meristem initiation and maintain indeterminate adventitious root growth is still a fascinating “enigma” after more than 30 years since their identification. However, evidence exists that they may act through the modification of as-of-yet unknown enzymatic reactions in the metabolism/signaling of cytokinins, auxin, and gibberellins as well as in ROS signaling [1]. In light of the current deep knowledge on root meristem formation and maintenance in Arabidopsis , it would be interesting to study the effect of rol genes in this model system to eventually identify their candidate target genes and pathways and understand their mode of action.…”

“…These GRNs are driven by different classes of transcription factors, the most important of which are NAC domain (NAM/ATAF/CUC), LBD (lateral organ boundaries domain), and KNOTTED1-like homeobox (KNOX) transcription factors (TFs). A specific section in De Paolis et al [1] is also dedicated to KNOX TFs. Since boundary specification have a profound effect on leaf shape and plant productivity, GRN-based strategies to exploit this knowledge for crop genetic improvement are suggested.…”

“…Domenico never believed in a clear distinction between fundamental and applied science; this is shown by his many scientific contributions to the field of cellular and molecular biotechnology in plants of agricultural interest spanning from basic to applied research. The review from De Paolis et al [1] is dedicated to him, and summarizes the recent advances obtained in plant biotechnology and fundamental research following Mariotti scientific interests as guiding principles. Most of these themes recur throughout the Special Issue, where specific papers deepen into basic principles of developmental transitions and organogenesis, giving them a perspective in applied research and crop genetic improvement.…”

Segregation of rol Genes in Two Generations of Sinningia speciosa Engineered Through Wild Type Rhizobium rhizogenes

“…Hairy roots are of interest because of their capacity to produce secondary metabolites (Giri and Narasu, 2000;Talano et al, 2012;De Paolis et al, 2019). However, there is an emerging interest in plants regenerated from hairy root tissue because of specific morphological characteristics commonly referred to as the Ri phenotype (Christey, 2001).…”