Plant regeneration and <i>Agrobacterium</i>-mediated genetic transformation systems in liliaceous ornamental plants

Abstract

The family Liliaceae (Cronquist system) contains various important ornamental plants. We have been examining for about 20 years the establishment of plant regeneration and genetic transformation systems in liliaceous ornamental plants for their biotechnological breeding and elucidation of the molecular mechanisms determining ornamental traits. In this review, studies on in vitro plant regeneration in 7 genera and on Agrobacterium-mediated production of transgenic plants in 4 genera are described. Plant regeneration was achieved via callus cultures in Agapanthus, Hemerocallis, Hosta, Lilium, Muscari and Tricyrtis. Auxins (2,4-dichrolophenoxyacetic acid, α-naphthaleneacetic acid and/or picloram) were effective for inducing regenerable calli. Tulipa species and cultivars were very recalcitrant to callus induction and plant regeneration. Agrobacterium-mediated transformation was examined in Agapanthus, Lilium, Muscari and Tricyrtis, and transgenic plants were obtained in all genera by using regenerable calli as a target material for Agrobacterium inoculation, inoculation and co-cultivation with Agrobacterium in the presence of acetosyringone, and selection of transgenic tissues and plantlets on hygromycin-containing media. Among 4 genera, Tricyrtis has several advantages for transformation studies: higher transformation efficiency, relatively small plant size, ease of cultivation, and taking only 1 year from in vitro regeneration to flowering. We are now investigating the molecular mechanisms for determining plant form, flower color and flower form by using Tricyrtis spp. as liliaceous model plants.

Induction of dwarf and early flowering phenotypes in <i>Tricyrtis</i> sp. by ectopic expression of <i>LEAFY</i> from <i>Arabidopsis thaliana</i>

“…We have been using Tricyrtis spp. as model plants in liliaceous ornamental plants for basic and applied researches for the following reasons: high transformation efficiencies, relatively small plant sizes, ease of cultivation, and taking only one year from in vitro regeneration to flowering (Nakano and Otani 2020).…”

“…Tepal-derived embryogenic callus cultures of a tetraploid somaclonal variant of Tricyrtis sp. 'Shinonome' (Nakano et al 2006) were induced and maintained as previously described (Nakano and Otani 2020). A. tumefaciens strain EHA101/pIG-AtLFY was used for transformation.…”

“…A. tumefaciens strain EHA101/pIG121-Hm (accession number AB489142 in the GenBank/EMBL/DDBJ databases) was also used as a vector control. Cocultivation of embryogenic calli with Agrobacterium, selection of transgenic cells and tissues, and regeneration of transgenic plants were performed as previously described (Nakano and Otani 2020). Transgenic plants and the vector control plants were transplanted to pots and cultivated in a growth chamber at 25°C under a 16-h photoperiod.…”

A highly efficient genetic transformation system for broccoli and subcellular localization

“…Agrobacterium-mediated genetic transformation has been widely used in plants for gene function analysis and regulatory mechanism research (Nakano and Otani, 2020;Zhang et al, 2021). It has also been widely used in cruciferous vegetable crops, including rapeseed, cabbage, broccoli, and kale.…”

Establishment of a Rapid and Effective Agrobacterium-Mediated Genetic Transformation System of Oxalis triangularis ‘Purpurea’

“…These factors collectively affect the transformation efficiency. The preferred conditions for the transformation of lily callus include bacterial OD 600 = 0.4–0.8, the infection time ranging from approximately 15 to 30 min, and AS 100 μM [ 8 ], co-cultured for 3 days [ 40 , 41 ]. Most of the lotus seeds were inoculated with Agrobacterium (OD 600 = 0.6) for 1–5 min and cultured for 2–7 days [ 42 ].…”