The rooting of stem cuttings is a highly efficient procedure for the vegetative propagation of ornamental plants. In cultivated carnations, an increased auxin level in the stem cutting base produced by active auxin transport from the leaves triggers adventitious root (AR) formation from the cambium. To provide additional insight into the physiological and genetic basis of this complex trait, we studied AR formation in a collection of 159 F1 lines derived from a cross between two hybrid cultivars (2003 R 8 and 2101-02 MFR) showing contrasting rooting performances. In three different experiments, time-series for several stem and root architectural traits were quantified in detail in a subset of these double-cross hybrid lines displaying extreme rooting phenotypes and their parental genotypes. Our results indicate that the water content and area of the AR system directly contributed to the shoot water content and shoot growth. Moreover, morphometric data and rooting quality parameters were found to be associated with some stress-related metabolites such as 1-aminocyclopropane-1-carboxylic acid (ACC), the ethylene precursor, and the conjugated auxin indol-3-acetic acid-aspartic acid (IAA-Asp)., This research was funded by the Ministerio de Economía, Industria y Competitividad (MINECO) of Spain (grants no. AGL2012-33610 and BIO2015-64255-R), by the Center for the Development of Industrial Technology (CARNOMICS Eurostars-EUREKA Project E! 6384), and by the European Regional Development Fund (ERDF) of the European Commission., http://creativecommons.org/licenses/by/4.0/, Peer reviewed

Some plant cells are able to rebuild new organs after tissue damage or in response to definite stress treatments and/or exogenous hormone applications. Whole plants can develop through de novo organogenesis or somatic embryogenesis. Recent findings have enlarged our understanding of the molecular and cellular mechanisms required for tissue reprogramming during plant regeneration. Genetic analyses also suggest the key role of epigenetic regulation during de novo plant organogenesis. A deeper understanding of plant regeneration might help us to enhance tissue culture optimization, with multiple applications in plant micropropagation and green biotechnology. In this review, we will provide additional insights into the physiological and molecular framework of plant regeneration, including both direct and indirect de novo organ formation and somatic embryogenesis, and we will discuss the key role of intrinsic and extrinsic constraints for cell reprogramming during plant regeneration., This research was funded by the Ministerio de Economía, Industria y Competitividad (MINECO)of Spain (grant numbers BIO2015-64255-R and RTI2018-096505-B-I00 to JMP-P, and AGL2017-82447-R to PST),the Conselleria d’Educació, Cultura i Sport of the Generalitat Valenciana (grant numbers IDIFEDER 2018/016and PROMETEO/2019/117 to JMP-P), and the European Regional Development Fund (ERDF) of the EuropeanCommission. SI is a research fellow of the Generalitat Valenciana (grant number ACIF/2018/220)., Peer reviewed

Adventitious roots (ARs) are produced from non-root tissues in response to different environmental signals, such as abiotic stresses, or after wounding, in a complex developmental process that requires hormonal crosstalk. Here, we characterized AR formation in young seedlings of Solanum lycopersicum cv. ‘Micro-Tom’ after whole root excision by means of physiological, genetic and molecular approaches. We found that a regulated basipetal auxin transport from the shoot and local auxin biosynthesis triggered by wounding are both required for the re-establishment of internal auxin gradients within the vasculature. This promotes cell proliferation at the distal cambium near the wound in well-defined positions of the basal hypocotyl and during a narrow developmental window. In addition, a pre-established pattern of differential auxin responses along the apical-basal axis of the hypocotyl and an as of yet unknown cell-autonomous inhibitory pathway contribute to the temporal and spatial patterning of the newly formed ARs on isolated hypocotyl explants. Our work provides an experimental outline for the dissection of wound-induced AR formation in tomato, a species that is suitable for molecular identification of gene regulatory networks via forward and reverse genetics approaches., European Regional Development Fund; Generalitat Valenciana, Grant/Award Numbers: ACIF/2018/220, IDIFEDER 2018/016, PROMETEO/2019/117; Ministerio de Ciencia e Innovación, Grant/Award Numbers: BIO2015-64255-R, RTI2018-096505-B-I00