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Open access

Margaret A. Halstead, Andrea R. Garfinkel, Travis C. Marcus, Patrick M. Hayes, and Daniela R. Carrijo

Micropropagation is a valuable production tool for the cultivation of hemp (Cannabis sativa), and development of optimal protocols is ongoing. The goal of this study was to evaluate a novel growing medium combination, consisting of Driver and Kuniyuki Walnut (DKW) medium as the nutrient source and glucose as the carbon source, and to investigate the link between in vitro and in vivo (i.e., greenhouse) plant performance. Among 10 accessions intended to represent a range of heterozygosity levels and various essential oil chemotypes, the DKW–glucose growing medium generally produced the most vigorous plantlets by all parameters evaluated in vitro (height, biomass, canopy area, vegetative growth rate, and regeneration rate). Across four growing media treatments, all of which included meta-topolin as the sole plant growth regulator, poor to no rooting was observed in vitro. Hybrids were more vigorous than nonhybrid selections in vitro, but not in vivo. No correlation was observed between in vitro and in vivo vigor, indicating that, with these media, plant performance in vitro is not predictive of that in vivo.

Open access

Bing Li, Jingjing Zhang, Xiurui Gao, Xiuqing Pan, Rong Zhou, and Yanrong Wu

Thermosensitive genic male sterile (TGMS) lines are the core of two-line hybrid systems. MicroRNAs (miRNAs) play critical roles in plant growth and development. However, knowledge of regulation of anther development by miRNAs in TGMS eggplant (Solanum melongena) is largely unexplored. To investigate the mechanism underlying miRNA regulation of male sterility, we employed high-throughput small RNA sequencing in anther samples from the reverse TGMS line 05ms and the temperature-insensitive line S63 in eggplant, under high temperature and low temperature conditions. The 05ms line is sterile at low temperature and fertile at high temperature. A total of 166,273,427 raw reads were obtained, 143 known miRNAs from 42 miRNA families and 104 novel miRNAs were detected. Further, six differentially expressed miRNAs (DEMs) were identified, including three known (miR168b-3p, miR397–5p, and miR408) and three novel miRNAs (Novel_116, Novel_119, and Novel_97), which might be related to anther development. Moreover, the six DEMs were validated by quantitative real-time polymerase chain reaction and 892 target genes of which were predicted. Gene Ontology analysis of target genes revealed significant enrichment in the “copper ion binding,” “oxidation-reduction process,” and “oxidoreductase activity” terms. Kyoto Encyclopedia of Genes and Genomes analysis revealed that “plant hormone signal transduction” and “other glycan degradation” were enriched. In addition, we constructed regulatory networks comprising miRNAs, target genes, and important terms/pathways and found the miR397-5p was the most linked miRNA, down-regulated under low temperature. Our findings contribute to understanding of the roles of miRNA during anther development and provide the theoretical foundation for two-line hybrid breeding of eggplant.

Open access

Jinzhu Zhang, Yu Mo, Shuai Chen, Caihua Li, Qingxi Fang, Jie Dong, Zhongsheng Mou, Zheyu Zhang, Daidi Che, and Qingshan Chen

The DNA binding with one finger (Dof), as an important transcription factor, plays an important role in growth and development, primary and secondary metabolism, stress resistance, and plant hormone signal transduction. However, the identification and analysis of the Dof transcription factor family in Rosa is rarely reported. In this study, 28 Rosa chinensis Dof (RcDof) members were identified, which were located on seven chromosomes. The RcDofs were divided into 12 subfamilies according to evolutionary analysis. Through motif, gene structure, and cis-acting element analyses of the 12 subfamilies, the functions of RcDofs were analyzed and predicted. Furthermore, the Dof members in R. chinensis ‘Old Blush’ and another three species (Arabidopsis thaliana, Oryza sativa, and Zea mays) were systematically analyzed. Twelve subfamilies were found in these four species and the motifs and gene structures of Dof members in each subfamily were similar, which further proves that the RcDofs analysis is accurate. Through an intra- and interspecies collinearity analysis, it was found that the collinearity between A. thaliana and R. chinensis is closer in comparison. Tissue expression analysis of RcDofs was by quantitative reverse-transcription polymerase chain reaction (PCR). Quantitative real-time PCR analysis showed expressions of the RcDofs are tissue specific. The RcDofs had higher expression in leaves, roots, and flowers than other tissues. Taken together, this study provides valuable information for future research on functional exploration of RcDof genes and molecular breeding in Rosa.

Open access

Rebekah C.I. Maynard and John M. Ruter

Salvia is the largest genus in the Lamiaceae with more than 1000 species. The species S. coccinea used in this study has naturalized in the southeastern United States and is an important plant for pollinators. This project aimed to improve phenotypic characteristics of S. coccinea for use in the landscape by selecting for increased petal size and unique petal color. Two elite accessions were selected for hybridization using the pedigree method. One selection displayed compact habit with bicolored coral and white flowers, while the other was slightly larger with solid red flowers. Selections were made based on improved flower color and larger petal size. The breeding program achieved a 25% increase in petal width and a more vivid petal color for the coral bicolored selections. Additionally, a 60% increase in petal width was achieved for red flowers. These novel selections are attractive plants for the landscape, displaying improved ornamental value and supporting local pollinator populations.

Open access

Weiting Huang, Xiaoyan Huang, and Zhongming Fang

Melatonin plays an important role in plant resistance to stress. The role of melatonin in the propagation of plant tissue, such as rhizome proliferation, differentiation, and seedling rooting in Cymbidium species, remains unknown. In this study, we selected C. goeringii and C. faberi as experimental materials and attempted to understand the effect of melatonin on this process. We found that 1.0 μM melatonin was beneficial for rhizome proliferation of C. goeringii, with a proliferation rate of 5.52. In terms of C. faberi, the highest proliferation rate of 8.29 was observed in the medium with 0.5 μM melatonin. In proliferation, the cut rhizome of C. goeringii is more likely to cause browning phenomenon than that of C. faberi. The addition of melatonin can significantly inhibit the browning phenomenon and improve the survival rate of C. goeringii rhizome. The highest number of shoot buds per explant (3.11 after 60 days) was observed in the medium with 1.0 μM melatonin. The number of shoot buds per explant (3.28 after 60 days) was significantly higher for C. faberi in the medium with 5.0 μM melatonin than that for the control. Furthermore, culture medium incorporated with 1.0 μM of melatonin had the best comprehensive effect of seedling height and root number and length of C. goeringii. By contrast, 0.5 μM melatonin significantly promoted root elongation of C. faberi, reaching 1.77 cm, whereas it was 0.28 cm in the control. We demonstrated that melatonin in specific concentrations effectively promote rhizome proliferation, differentiation, and seedlings rooting in the rapid propagation of C. goeringii and C. faberi.

Open access

R. Paul Schreiner and Tian Tian

Grapevines rely on arbuscular mycorrhizal fungi (AMF) to obtain ample phosphorus (P) from soils with low to moderate P like the Ultisols of western Oregon. Prior research indicated that nine species, or virtual taxa, of AMF colonized the roots of ‘Pinot noir’ at greater than 1% abundance in a single vineyard. However, little is known about how different taxa within a community vary in their capacity to function as symbionts with grapevines. The effectiveness of five native AMF species representing five genera to promote growth and nutrient uptake of ‘Pinot noir’ was examined in a fumigated Ultisol soil under well-watered and periodically dry conditions. Plants were grown with each of the different isolates alone or without AMF. After 8 and 16 weeks, whole vines were destructively harvested and biomass and nutrients were determined. Results showed that four of the isolates colonized roots extensively, increased root and shoot biomass, and predominantly increased P uptake. A Claroideoglomus isolate was superior in promoting shoot growth as compared with Rhizophagus irregularis, even though both isolates increased P uptake to the same extent, suggesting a higher carbon cost for R. irregularis. Scutellospora calospora failed to colonize roots beyond a trace and had no impact on vine performance. The ability to increase P uptake among the four effective fungi was not related to the frequency of arbuscules in roots suggesting that some P exchange occurs via hyphae within the cortex, particularly for Funneliformis mosseae. Water limitation reduced P uptake as a main effect across all mycorrhizal treatments, suggesting that the native isolates studied here have similar functionality under well-watered and periodically dry conditions.

Open access

Michael J. Havey

The amounts and types of epicuticular waxes on onion (Allium cepa) leaves affect feeding damage by onion thrips (Thrips tabaci), a serious insect pest of onion. This study used gas chromatography mass spectrometry (GCMS) to measure amounts of epicuticular waxes on foliage of two plants from each of 50 plant introductions (PI) and inbred lines with high (waxy) and low (glossy) amounts of wax. Wax amounts on leaves of the same plants were measured twice (once in the greenhouse and once after moving plants outside) and were significantly (P < 0.01) correlated; however, wax amounts on leaves of plants grown in the greenhouse were approximately twice that of the same plants grown outside. Hentriacontanone-16 (H16) was the predominant wax on leaves of all PIs except PI 289689, and amounts of H16 were significantly correlated with amounts of fatty alcohols and total wax. Five plants from 17 of the PIs were grown in the greenhouse, wax amounts measured using GCMS, and results were significantly correlated with earlier evaluations. Results indicate that measurements of waxes on onion foliage should occur under protected conditions to better characterize phenotypic variation, and selection of higher amounts of waxes other than H16 may be effective toward the development onions suffering less thrips damage.