@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={AbstractBackgroundTripidium ravennaeis a cold-hardy, diploid species in the sugarcane complex (PoaceaesubtribeSaccharinae) with considerable potential as a genetic resource for developing improved bioenergy and ornamental grasses. An improved understanding of the genetic regulation of reproductive processes (e.g., floral induction, inflorescence development, and seed development) will enable future applications of precision breeding and gene editing of floral and seed development. In particular, the ability to silence reproductive processes would allow for developing seedless forms of valuable but potentially invasive plants. The objective of this research was to characterize the gene expression environment of reproductive development inT. ravennae.ResultsDuring the early phases of inflorescence development, multiple key canonical floral integrators and pathways were identified. Annotations of type II subfamily of MADS-box transcription factors, in particular, were over-represented in the GO enrichment analyses and tests for differential expression (FDRp-value < 0.05). The differential expression of floral integrators observed in the early phases of inflorescence development diminished prior to inflorescence determinacy regulation. Differential expression analysis did not identify many unique genes at mid-inflorescence development stages, though typical biological processes involved in plant growth and development expressed abundantly. The increase in inflorescence determinacy regulatory elements and putative homeotic floral development unigenes at mid-inflorescence development coincided with the expression of multiple meiosis annotations and multicellular organism developmental processes. Analysis of seed development identified multiple unigenes involved in oxidative-reductive processes.ConclusionReproduction in grasses is a dynamic system involving the sequential coordination of complex gene regulatory networks and developmental processes. This research identified differentially expressed transcripts associated with floral induction, inflorescence development, and seed development inT. ravennae. These results provide insights into the molecular regulation of reproductive development and provide a foundation for future investigations and analyses, including genome annotation, functional genomics characterization, gene family evolutionary studies, comparative genomics, and precision breeding.}, 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={AbstractHigh biomass yields have been documented for Tripidium spp. (Erianthus spp., Saccharum spp.), but targeted breeding for bioenergy applications has been limited. Advanced, interspecific hybrids between Tripidium ravennae and T. arundinaceum were planted in replicated field plots in 2016. Comparative feedstock evaluations examined biomass yields, cytogenetics, plant fertility, and compositional analyses relative to Miscanthus × giganteus. Dry biomass yields varied as a function of year and accession and increased each year ranging from 3.4 to 10.6, 8.6 to 37.3, and 23.7 to 60.6 Mg/ha for Tripidium hybrids compared to 2.3, 16.2 and 27.9 Mg/ha for M. × giganteus in 2016, 2017, and 2018, respectively. Cytology and cytometry confirmed that Tripidium hybrids were tetraploid with 2n = 4x = 40 (2C genome size = 5.06 pg) and intermediate between T. ravennae with 2n = 2x = 20 (2C genome size = 2.55 pg) and T. arundinaceum with 2n = 6x = 60 (2C genome size = 7.61 pg). Plant fertility characteristics varied considerably with some accessions producing no viable seeds or fewer than that observed for M. × giganteus. Accessions varied significantly for flowering culm number and height and dates of peak anthesis ranging from 14 September to 2 October. Variations in yield and compositional analyses contributed to variations in theoretical ethanol yields ranging from 10,181 to 27,546 L/ha for Tripidium accessions compared to 13,095 L/ha for M. × giganteus. Relative feed value (RFV) indices for winter‐harvested Tripidium accessions varied from 52.8 to 60.0 compared to M. × giganteus with 45.4. RFV for summer‐harvested Tripidium accessions varied from 71.6 to 80.5 compared to M. × giganteus with 61.0. These initial findings for Tripidium hybrids, including high biomass yields, cold hardiness, and desirable traits for multiple markets (e.g., forage, bioenergy, bioproducts), are promising and warrant further development of Tripidium as a temperate bioenergy feedstock.}, 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} }