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Control of development is an important issue in the production of ornamental plants. Gibberellins (GAs) play a key role in regulating plant growth and development. DELLA is nuclear negative regulators of GA signaling. We identified two DELLA homologous genes, PmDELLA1 and PmDELLA2, in the genome of mei (Prunus mume) genome. We analyzed the structure, expression patterns and molecular functions of both genes. Tissue expression analysis showed that both genes were transcriptionally active. PmDELLA1 showed higher expression in seeds than PmDELLA2. This indicated that PmDELLA2 plays different roles from PmDELLA1 in seed germination. The expressions of both genes at various flowering stages were relatively low. We speculated that PmDELLAs might be positive regulators of flowering by releasing the repression of GA during floral blooming. Transgenic arabidopsis (Arabidopsis thaliana) lines overexpressing the two genes showed dwarf and delayed flowering. We confirmed that the two PmDELLAs were partially conserved with genes encoding DELLA proteins in arabidopsis. Our bioinformatics and functional analyses provide information that may be valuable to improve the economic, agronomic and ecological properties of mei and other Rosaceae fruit trees.
Drought is the most important abiotic stress in crop production including turfgrass management. Using drought tolerant plants can help minimize stress damage. In this study, 23 commercially available cultivars of creeping bentgrass (Agrostis stolonifera) were evaluated for their responses to drought stress that was induced by polyethylene glycol (PEG) 6000 in a hydroponic system during the seed germination and seedling growth stage. In such a system, water potential was adjusted to 0.0 (the control), −0.3, and −0.6 MPa to mimic the drought condition. The absolute water content (AWC), shoot dry weight (SDW), root dry weight (RDW), longest root length (LRL), specific root length (SRL), and root-to-shoot dry weight ratio (RSR) in the plants grown for 4 weeks in the treatment were determined. Results showed that SDW and LRL were unaffected by drought; however, RDW and RSR increased, whereas SRL and AWC were reduced under drought. Among the 23 creeping bentgrass cultivars evaluated, Independence and Crystal Bluelinks had a higher turfgrass performance index (TPI), which represented the number of times a cultivar ranked in the top statistical group across all parameters. The results suggest that ‘Independence’ and ‘Crystal Bluelinks’ may be more adapted to drought than the other cultivars at the seedling stage.
The evergreen Ligustrum lucidum (glossy privet) suffers from freezing injury in northern China, where there are short growing seasons and early fall frost events. To investigate the influence of exogenous salicylic acid (SA) application on the natural cold acclimation of glossy privet, physiological and biochemical changes in glossy privet seedlings subjected to SA treatments at four concentrations (0, 150, 250, and 350 mg·L−1) were evaluated from Sept. to Dec. 2016. The optimum application concentrations were between 250 and 350 mg·L−1, which led to better freezing tolerance during natural cold acclimation. The improved freezing tolerance under exogenous SA application was associated with the accumulation of chlorophyll, proline, soluble protein, and soluble sugar, and the regulations of gibberellic acid (GA) and abscisic acid (ABA). Salicylic acid treatments started a cascade of steps for advancing the cold acclimation process of glossy privet. We suggest that exogenous SA application may be used on glossy privet grown in northern China.
Rhododendron delavayi Franch. is an important ornamental plant and often plays a role in natural hybridization with other sympatric species in Rhododendron subgenus Hymenanthes. Fifteen microsatellite loci were developed and characterized in this species. The average allele number of these microsatellites was four per locus, ranging from three to six. The ranges of expected (HE ) and observed (HO ) heterozygosities were 0.0365 to 0.7091 and 0.0263 to 0.9512, respectively. Cross-species amplification in R. agastum and R. decorum showed that a subset of these markers holds promise for congeneric species study. These sets of markers are potentially useful to investigate the genetic structure and gene flow of R. delavayi and other congeneric species.
Bletilla is an Orchidaceae genus with high medical value, including detumescence, antibacterial, and hemostasis. In this study, detailed estimates of ploidy level, karyotype, and genome size were first obtained, and a comprehensive cytological analysis was carried out to better understand the evolution of the genus. The karyotypes of Bletilla were mainly composed of metacentric and submetacentric chromosomes with lengths ranging from 1.25 to 4.93 μm. There was moderate cytological variation in Bletilla (chromosome number 2n = 32 to 76). Diploid with 2n = 34 and 2n = 36 was detected in Bletilla ochracea and Bletilla formosana, respectively, whereas diploid (2n = 32) was dominant in Bletilla striata, dysploidy (2n = 34, 2n = 36) and polyploid (2n = 48, 51, 64, 76) variations were also observed. Three species had a relatively symmetric karyotype, and which of B. ochracea was more asymmetry. The genome size (1C-values) varied from 2.94 pg (B. striata) to 3.33 pg (B. ochracea), of which B. ochracea was significantly larger than the others (P < 0.05). A positive correlation (P < 0.01) between 1Cx vs. haploid chromosome length (HCL) and asymmetry coefficient of karyotypes (AsK%) was observed.
Chrysopogon aciculatus (Retz.) Trin. is a perennial turfgrass for its low management and resistance. To develop simple sequence repeat (SSR) markers for C. aciculatus, we used four Roche 454 pyrosequencing, combined with the magnetic bead enrichment method FIASCO (fast isolation by amplified fragment length polymorphism of sequences containing repeats) to isolate from the C. aciculatus. A total of 66,198 raw sequencing reads were obtained with 4289 sequences (6.48%) were fit for primer pair design. One hundred microsatellite loci were selected to test the primer amplification efficiency in 20 accessions, and out of these, 11 loci were polymorphic. The amount of observed alleles ranged from three to six, with an average of 3.64. Nei’s genetic diversity values ranged from 0.085 to 0.493, with an average of 0.293. Shannon’s information index values ranged from 0.141 to 0.686, with an average of 0.428. Twenty accessions were clustered into three groups by unweighted pair-group method with arithmetic means (UPGMA). These SSR markers will provide an ideal marker system to assist with gene targeting, cultivar variety or species identification, and marker-assisted selection in C. aciculatus species.