Date palm (Phoenix dactylifera L.) is one of the oldest cultivated perennial woody plant species with significant agricultural and economic importance. Date has its center of origin in the Middle East, spreading in ancient times to North Africa and South Asia and later to other hot, arid areas. Dates are a strict dioecious evergreen, obligate outcrossing, and highly heterozygous monocot species that are typically vegetatively propagated. ‘Medjool’ and ‘Deglet Noor’ are the most widely grown date cultivars in the United States and are also important at the global level. Despite their economic values, genomic studies have been hampered due to lack of available assembled genomes. To facilitate future genomic studies, genomes for ‘Medjool’ and ‘Deglet Noor’ were assembled using Dovetail® HiFi and Omni-C® technologies. ‘Medjool’ had a total length of 757 Mb comprising 899 scaffolds (L50 : 7, N50 : 37 Mb) with a BUSCO completeness score of 97.65 %, and ‘Deglet Noor’ had a total length of 772 Mb comprising 1287 scaffolds (L50 : 9, N50 : 33 Mb) with a BUSCO completeness score of 97.65 %.
Pomegranates (Punica granatum L.) are a significant fruit crop globally, gaining traction due to their high nutritional value and many uses outside of consumption. Despite increasing interest, genetic resources for pomegranates lag behind other crops. Developing these resources can enhance breeding efficiency and deepen genomic understanding. To address this, we sequenced the genomes of two cultivars: 'Azadi', known for its robust fruit rot resistance, and 'Peppy Le Pom', a dwarf variety with short juvenility. Using the PacBio Revio Platform, we generated HiFi reads with 30x coverage and employed Hi-C for sequencing. Leveraging hifiasm's Hi-C integrated assembly method, we assembled two haplotypes for the genome of each cultivar. For 'Peppy Le Pom', we utilized 10.03 Gb of PacBio HiFi reads and 30 Gb of Hi-C data and constructed two haplotypes with eight chromosome-length scaffolds each, totaling 304.9 Mb and 318.7 Mb, with a BUSCO score of 90.3% and 92.3%, respectively. For 'Azadi', we utilized 10.08 Gb of Pacbio HiFi reads and 30 Gb of Hi-C data and assembled two haplotypes with eight chromosome-length scaffolds, measuring 305.5 Mb and 318.1 Mb, with a BUSCO score of 91.0% and 92.6%, respectively. Chromosome sizes of these pomegranate cultivars range from 27.1 Mb to 62.4 Mb. Notably, these results closely align with the previously published draft genome of the 'Tunisia' cultivar. These phased, chromosome-scale genomes will facilitate further exploration of traits of interest for pomegranate breeding, such as disease resistance, dwarfing, and short juvenility. The genomic resources established here pave the way for accelerated advancements in pomegranate research and breeding.
Catharanthus roseus (L.) G. Don is a common ornamental crop worldwide due to its high tolerance to drought and heat. The researches on Agrobacterium-mediated transformation of C. roseus are few, and mostly focus on the production of secondary metabolites in roots. Furthermore, the organogenesis from callus to plantlet is frequently unstable which limits the study on entire plant, especially on flowering. The objective of this study is to evaluate the in planta transformation survival rate in different explants and Agrobacterium strains. C. roseus ‘Cora XDR White’ seeds were cultivated in vitro till the cotyledon expanded. Plantlets and cotyledonary nodes were respectively inoculated with two Agrobacterium strains, GV3101 or LBA4404 harboring the binary vector pHEE401E. Explants were co-cultivated in 1/2 MS medium for three days. After washing with sterile water and cefotaxime, the explants were first placed in a medium containing cefotaxime, then were transferred to a same medium that was further added hygromycin. During the elimination and selection, each cotyledonary node turned brown. In the process of subculture, necrotic parts were removed. Result showed that the survival rate of plantlets was 5% in GV3101 treatment. However, LBA4404 ones eventually got brown.
Aroniaberry or chokeberry (Aronia sp., Rosaceae) is an attractive deciduous tree-like shrub. Native to eastern and central United States, red aroniaberry (A. arbutifolia) is more predominant in the southern part of the distribution. Bright red fruits, proliferous white flowers in spring, and attractive fall color, make A. arbutifolia a native shrub with ornamental potential. Most of the aroniaberry ornamental varieties available in the market are selections or hybrids of black aroniaberry (A. melanocarpa), they produce black fruit, and do not perform well in sub-tropical climates. We collected triploid and tetraploid A. arbutifolia from five different locations in South Georgia and evaluated their flowering period, fruit production, and response to chill hours in Griffin, GA (Zone 8a, Piedmont region). Plants were exposed to 1000, 800, 600, 400, or 0 chill hours and planted in the field in April of 2023. Flowering timing had a strong correlation with chill hours; plants with chill hours below 600 hrs. presented less flowers and flowering was not uniform.
The Hibiscus genus, encompassing roughly 300 species across 10 sections, presents a diverse and economically significant range of industrial, ornamental, and medicinal properties. Polyploidy, whether occurring spontaneously or induced through external agents, such as chemicals like colchicine and oryzalin, plays a crucial role in plant breeding. It enhances various attributes including flower size, resilience, and metabolite production. Among the species in this genus, Hibiscus hamabo is noted for its salt tolerance and its attractive yellow flowers in summer and golden-yellow or burnt orange leaves in fall. However, H. hamabo typically has small and sparse flowers, which led to our efforts to enhance its ornamental value through induced polyploidy. In our study, we treated germinating seeds of H. hamabo with three concentrations of colchicine (0, 0.125, and 0.25% v/v) for varying durations (6, 12, or 24 hours). The most effective conversion was achieved with seeds treated with 0.25% v/v colchicine for 24 hours. This treatment produced solid polyploids (4n = 184) and mixed-polyploids (2n 4n). The 4n plants exhibited a 2C-DNA content of 8.50 pg, compared to 4.23 pg in the untreated (2n = 92) plants. We evaluated the impact of induced polyploidy on several morphological traits including leaf color, shape, size, trichome density, and plant height. Significant differences were observed between the polyploid plants and the control plants. Additionally, we explored the cytomolecular analysis of induced polyploidy, particularly focusing on the distribution and organization of rDNA. In 2n plants, one locus of 5S and four loci of 35S rDNA (two major and two minor) were identified. The 5S site is pericentromeric, while one of the major 35S sites is sub-terminal, and the others are at terminal locations. In 4n plants, the number of 5S and 35S sites was exactly duplicated, confirming the polyploidization at the genetic level. Our results proved that colchicine can be used to induce polyploidy in germinating H. hamabo seeds, paving the way for the improvement of this species through this method.
The wealth of genetic and phenotypic diversity in plant species serves as the primary source of novel traits in plant breeding and crop improvement efforts. Spinach (Spinacia oleracea) has a long cultivation history across diverse environments and geographic regions, which has resulted in adaptation to diverse conditions. This adaptation has been influenced further by human preferences for distinct leaf shapes, tastes, flavors, and nutrition, constituting a rich reserve of genetic and phenotypic diversity within Spinacia germplasm. Moreover, wild species (S. tetrandra and S. turkestanica) offer valuable resources, particularly for traits of commercial significance, such as resistance to prevalent pathogens and pests. Therefore, understanding the genetic variations that underlie phenotypic traits is crucial to enable effective gene introgression and the development of novel spinach varieties. We recently investigated the genetic diversity and population structure of a panel of over 500 cultivated and wild germplasm obtained from the Centre for Genetic Resources, the Netherlands (CGN) at Wageningen University and Research (WUR). This panel, complemented with material from other sources, comprised 49 S. tetrandra and 86 S. turkestanica accessions. Our findings revealed the presence of significant genetic diversity within these panels of accessions, which were categorized into multiple distinct population groups. We evaluate this Spinacia panel for several horticulturally important traits to identify SNP markers and candidate gene regions associated with commercially important traits. Our objectives are to share novel insights into the genetic diversity of spinach and provide valuable molecular markers for improving cultivated spinach production.
Dr. Ainong Shi is a faculty member in the Department of Horticulture at the University of Arkansas. His research laboratory specializes in plant breeding and genetics, particularly focusing on vegetable crops such as arugula, cowpea, and spinach for cultivar and germplasm development... Read More →
Schoenocaulon officinale or sabadilla (Melianthiaceae) is endemic to the Americas with Mexico as the Center of Origin and Diversity. Sabadilla is a subtropical geophytic perennial, producing tunicate bulbs. It reproduces by seed and asexually (daughter bulbs), producing apetalous floral inflorescences. Flowering occurs >1.5 years from seed with annual flowering occurring up to eight years. Sabadilla seeds contain two insecticidally active lipophilic alkaloid compounds: veratridine and cevadine, in concentrations of 0.5-6.0%. These compounds are used as “green pesticides” with a mode of action that is similar to pyrethrins; attachment to sodium channels in insects, causing continuous overactivation. Sabadilla has been used by Native American cultures for thousands of years for its insecticidal properties and medicinal uses. However, about sabadilla, little is known about this species as a crop plant. The purpose of this research was to examine population differences of extant, wild collections in Venezuela. In 2019, seeds (24 subsample seed lots from sympatric plants, bulked by site) were collected from seven locations in The Ávila National Park and the vicinity of Colonia Tovar across three different states (Vargas, Miranda, Aragua). Seed lots were germinated to determine % germination and genetic variation. Dried leaf samples (n=333 genotypes) were used for DNA extraction for genotype by sequencing (GBS) for low-density single nucleotide polymorphic (SNP) marker generation (DArT-seq). Genetic variation within and among populations was determined using principle component, Admixture, AMOVA, and IBS analyses (RStudio).
