@article{touchell_lynch_shekasteband_dickey_chinn_whitfield_ranney_2024, title={Biomass yields, reproductive fertility, compositional analysis, and genetic diversity of newly developed triploid giant miscanthus hybrids}, volume={16}, ISSN={["1757-1707"]}, url={https://doi.org/10.1111/gcbb.13174}, DOI={10.1111/gcbb.13174}, abstractNote={Abstract Miscanthus × giganteus (giant miscanthus), first found as a naturally occurring hybrid, has shown promise as a bioenergy/biomass crop throughout much of the temperate world. This allotriploid (2 n = 3 x = 57) hybrid resulted from a cross between tetraploid Miscanthus sacchariflorus (2 n = 4 x = 76) and diploid Miscanthus sinensis (2 n = 2 x = 38) and is particularly desirable due to its low fertility that minimizes reseeding and potential invasiveness. However, there is limited genetic diversity in commonly grown cultivars of triploid M. × giganteus and breeding and development efforts to improve and domesticate this crop have been minimal. Here, we report on newly developed M. × giganteus hybrids compared with the industry standard M. × giganteus '1993‐1780'. Dry biomass yields of new hybrids ranged from 19.5 to 32.4 Mg/ha/year for the fourth growing season, compared with 21.0 Mg/ha/year for M. × giganteus '1993‐1780'. Plant reproductive fertility remained low for all accessions with overall fertility [(seed set × seed germination)/100] ranging from 0.3% to 4.5% for new hybrids compared to 0.4% for M. × giganteus '1993‐1780'. Culm density and height varied among accessions and were positively correlated with increased biomass. Based on compositional analyses, theoretical ethanol yields ranged from 9, 740 to 16,278 L/ha/year for new hybrids compared to 10,406 L/ha/year for M. × giganteus '1993‐1780'. Relative feed value indices were low overall and ranged between 66.0 and 72.8 for new hybrids compared to M. × giganteus '1993‐1780' with 71.3. The genetic diversity of new hybrids, compared with existing cultivars, was characterized using whole genome sequences. Based on pair‐wise distances, cluster analysis clearly showed increased diversity of new hybrids compared with earlier selections. These results document new triploid hybrids of M. × giganteus with enhanced biomass and theoretical ethanol yields in combination with broader genetic diversity and lowreproductive fertility.}, number={7}, journal={GLOBAL CHANGE BIOLOGY BIOENERGY}, author={Touchell, Darren H. and Lynch, Nathan and Shekasteband, Reza and Dickey, Allison N. and Chinn, Mari C. and Whitfield, Matthew and Ranney, Thomas G.}, year={2024}, month={Jul} }
 @article{harmon_touchell_ranney_da_liu_2022, title={Tissue Culture and Regeneration of Three Rose Cultivars}, volume={57}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI16716-22}, abstractNote={Methods of in vitro regeneration protocols were developed for three elite rose cultivars, Chewnicebell (Oso Easy Italian Ice®), Bucbi (Carefree Beauty™), and Cheweyesup (Ringo All-Star™). We evaluated the effects of different types and concentrations of auxins [dichlorophenoxyacetic acid (2,4-D) and trichlorophenoxyacetic acid (2,4,5-T)], carbohydrates [sucrose, glucose, and fructose], and cytokinins [thidiazuron (TDZ) and 6-bezylaminopurine (BAP)] on callus induction and regeneration from leaf explants. The greatest amount of regenerative callus was obtained on media containing 10 µM 2,4-D and 30 g·L−1 sucrose for Italian Ice® (40%), 10 µM 2,4-D and 60 g·L−1 glucose for Carefree Beauty™ (24%), and 5 µM 2,4,5-T and 30 g·L−1 sucrose for Ringo All-Star™ (32%). The greatest regeneration occurred when callus was transferred to media consisting of 1/2 MS media supplemented with 2.9 µM GA3 and 5 µM TDZ for Italian Ice® and Ringo All-Star™, and with 2.9 µM GA3 and 20 µM TDZ for Carefree Beauty™. Plantlets regenerated from callus were cultured on maintenance media and successfully transferred ex vitro. This study highlights the genotype-specific responses among rose cultivars and provides the first reports of in vitro regeneration for Italian Ice® and Ringo All-Star™.}, number={11}, journal={HORTSCIENCE}, author={Harmon, Davis D. and Touchell, Darren H. and Ranney, Thomas G. and Da, Kedong and Liu, Wusheng}, year={2022}, month={Nov}, pages={1430–1435} }
 @article{deans_palmer_touchell_ranney_2021, title={In Vitro Induction and Characterization of Polyploid Hydrangea macrophylla and H. serrata}, volume={56}, ISSN={["2327-9834"]}, DOI={10.21273/HORTSCI15783-21}, abstractNote={Hydrangea macrophylla (Thunb.) Ser. and H. serrata (Thunb.) Ser. are popular and commercially important landscape and floriculture crops. Although both species are typically diploid, induced polyploids often exhibit horticulturally valuable traits. Procedures for inducing polyploidy vary by species and often have low or inconsistent efficacy. In this study, oryzalin and nitrotyrosine were investigated as in vitro mitotic inhibitors for inducing polyploidy in H. macrophylla ‘Robert’ and H. serrata ‘MAK20’. First, shoot apices of ‘MAK20’ were treated with 15 μm oryzalin for 0, 2, 4, 6, or 8 days, and the ploidy of shoots was determined after 8 weeks. A regression analysis showed that the proportion of polyploids (tetraploid plus mixoploid shoots) increased with the exposure duration. During a follow-up experiment, ‘MAK20’ and ‘Robert’ were treated with oryzalin (0 or 15 μm) and nitrotyrosine (0, 25, 50, and 100 µm for ‘MAK20’ and 0, 12.5, 25, 50, and 100 µm for ‘Robert’) in a factorial treatment arrangement. Oryzalin, nitrotyrosine, and their interaction influenced polyploid frequency for ‘Robert’, whereby the combination of oryzalin (15 μm) and nitrotyrosine (50 μm) resulted in the highest polyploid induction of 50%. Oryzalin influenced polyploid frequency for ‘MAK20’ ( = 30.4%), but not nitrotyrosine or the interaction between nitrotyrosine and oryzalin. Morphology and pollen germination of these autotetraploid ‘Robert’, ‘MAK20’, and previously developed autotetraploid H. macrophylla ‘David Ramsey’ plants were compared with their diploid counterparts 1 year after plants were moved ex vitro. Compared with diploids, tetraploid hydrangeas had larger leaves, thicker stems, lower leaf area/fresh weight ratios, and longer internodes. Although all tetraploids exhibited fewer inflorescences per plant, both H. macrophylla cultivars had larger inflorescence diameters and ‘David Ramsey’ had a greater number of showy florets (sterile florets with enlarged, decorative sepals) per inflorescence. Sepal colors were compared using International Commission on Illumination L*a*b* color space. Tetraploid ‘MAK20’ had lower L* values (darker sepals), and tetraploid ‘Robert’ and ‘MAK20’ both had higher a* values (redder sepals). Pollen germination rates were greatly reduced in all tetraploid lines, but they retained some viability. These results provide an effective protocol for in vitro polyploid induction of Hydrangea sp. and documented certain desirable traits associated with tetraploid phenotypes.}, number={6}, journal={HORTSCIENCE}, author={Deans, Lauren E. and Palmer, Irene E. and Touchell, Darren H. and Ranney, Thomas G.}, year={2021}, month={Jun}, pages={709–715} }
 @article{maren_zhao_aryal_touchell_liu_ranney_ashrafi_2021, title={Reproductive developmental transcriptome analysis of Tripidium ravennae (Poaceae)}, volume={22}, ISSN={["1471-2164"]}, DOI={10.1186/s12864-021-07641-y}, abstractNote={Abstract}, number={1}, journal={BMC GENOMICS}, author={Maren, Nathan and Zhao, Fangzhou and Aryal, Rishi and Touchell, Darren and Liu, Wusheng and Ranney, Thomas and Ashrafi, Hamid}, year={2021}, month={Jun} }
 @article{maren_touchell_ranney_ashrafi_whitfield_chinn_2020, title={Biomass yields, cytogenetics, fertility, and compositional analyses of novel bioenergy grass hybrids (Tripidium spp.)}, volume={12}, ISSN={["1757-1707"]}, url={https://doi.org/10.1111/gcbb.12676}, DOI={10.1111/gcbb.12676}, abstractNote={Abstract}, number={5}, journal={GLOBAL CHANGE BIOLOGY BIOENERGY}, author={Maren, Nathan A. and Touchell, Darren H. and Ranney, Thomas G. and Ashrafi, Hamid and Whitfield, Matthew B. and Chinn, Mari}, year={2020}, month={May}, pages={361–373} }
 @misc{touchell_palmer_ranney_2020, title={In vitroPloidy Manipulation for Crop Improvement}, volume={11}, ISSN={["1664-462X"]}, DOI={10.3389/fpls.2020.00722}, abstractNote={In vitro regeneration systems provide a powerful tool for manipulating ploidy to facilitate breeding and development of new crops. Polyploid induction can expand breeding opportunities, assist with the development of seedless triploid cultivars, enhance ornamental characteristics and environmental tolerances, increase biomass and restore fertility in wide hybrids. In vitro ploidy manipulation is commonly induced using antimitotic agents such as colchicine, oryzalin and trifluralin, while many other antimitotic agents have been relatively unexplored. Successful induction requires a synergistic pairing of efficient penetration of the antimitotic agent and may be dependent the length of exposure and concentrations of antimitotic agents, tissue types, and interactions with basal media and plant growth regulators. In vitro conditions vary among taxa and individual genera, species, and cultivars, often requiring unique treatments to maximize polyploid induction. In some taxa, the induction of polyploidy influences in vitro growth, development, and root formation. Here we provide an overview of mitotic inhibitors and their application for in vitro ploidy manipulation for plant breeding and crop improvement.}, journal={FRONTIERS IN PLANT SCIENCE}, author={Touchell, Darren H. and Palmer, Irene E. and Ranney, Thomas G.}, year={2020}, month={Jun} }