Five Wave™ petunias, i.e., `Purple Wave™', `Pink Wave™', `Misty Lilac Wave™', and `Rose Wave™', and two hedgaflora petunias, i.e., `Dramatica Cherry™', and `Dramatica Hot Pink™', were investigated to determine the effects of plant growth regulators on plant size, branching, and flowering. Plant regulator treatments consisted of daminozide (B-Nine) spray two times at 7500 ppm, Paclobutrazol (Bonzi) spray two times at 30 ppm, paclobutrazol drench at 5 ppm, paclobutrazol drench at 5 ppm plus spray at 30 ppm, and ethephone (Florel) spray two times at 500 ppm. Plant diameter and central stem height were controlled effectively through daminozide spray and paclobutrazol drench. Plant branching was promoted by ethephone and daminozide. However, time to flowering was delayed significantly in the ethephone treatment. The size of the first flower responded to plant growth regulators negatively. The different responses to growth regulators among different types of petunias and different varieties in the same petunia type will be discussed based on the current trial and other separated experiments.
Ying Wang, Cale A. Bigelow, and Yiwei Jiang
Perennial ryegrass (Lolium perenne L.) is a widely used cool-season turfgrass species. The exact ploidy levels of the worldwide perennial ryegrass accessions in the USDA National Plant Germplasm System (NPGS) are unknown, which could complicate future use and breeding efforts. The objective of this study was to determine the ploidy level and DNA content of the 194 USDA NPGS perennial ryegrass accessions and six commercial cultivars (Brightstar SLT, Catalina II, Divine, Inspire, Manhattan 4, Silver Dollar) using flow cytometry. Among the 200 accessions, 194 diploids and six tetraploids were identified. Three tetraploids originated from Canada with the remaining from Ireland, Japan, and The Netherlands. The average DNA content was 5.60 pg/2C for the diploid and 11.45 pg/2C for the tetraploid. The 2C DNA content was positively correlated (r = 0.23, P < 0.01) with seedling plant height but not seedling leaf width. This ploidy data provide important information for future marker trait analysis and cultivar improvement.
Jianjun Chen, Lijia Li, and Ying Wang
Epimedium species are traditional Chinese medicinal plants as well as potential groundcover and ornamental plants. In this study, genome size and genome structures of Epimedium species were investigated using flow cytometric and fluorescence in situ hybridization (FISH). The nuclear DNA content of Epimedium species ranged from 8.42 pg/2C (8230.7 Mbp) to 9.97 pg/2C (9752.8 Mbp). The pairwise nucleotide diversity (π) of the fragments of the genes for reverse transcriptase (rt) of Ty1-copia retrotransposon within a species of rt fragments ranged from 0.251 to 0.428 in 10 Epimedium species. Phylogenetic analysis of the sequences revealed four major clades with the largest subclade containing 72 sequences of relatively low nucleotide diversity. FISH indicated that Ty1-copia retrotransposons are distributed unevenly along the pachytene chromosomes of E. wushanense and E. sagittatum, mostly associated with the pericentromeric and terminal heterochromatin. The relatively low sequence heterogeneity of Ty1-copia rt sequences implies that the Epimedium genomes have experienced a few relatively large-scale proliferation events of copia elements, which could be one of the major forces resulting in the large genome size of Epimedium species.
Ying Wang, Ming Kang, and Hongwen Huang
Cross-species amplification of 55 microsatellite loci developed in european chestnut (Castanea sativa Mill.) and japanese chestnut (C. crenata Sieb & Zucc.) was tested in three chestnut species from China [C. mollissima Blume, C. seguinii Dode, and C. henryi (Skan.) Rehder & Wilson]. Among all the tested loci, 47 (85.5%), 47 (85.5%), and 44 (80%) were successfully amplified in each of the three Chinese species, respectively. All microsatellite loci tested from C. crenata successfully amplified in the Chinese species, while only 80.5%, 80.5%, and 73.2% of the loci originating from C. sativa amplified in the three Chinese species. The level of polymorphism and mean number of alleles was 58.2% and 4.12 for C. mollissima, 60% and 4.64 for C. seguinii, and 60% and 4.76 for C. henryi, with mean observed heterozygosity ranging from 0.440 to 0.549 and mean expected heterozygosity ranging from 0.506 to 0.615. Transferability of Castanea Mill. microsatellites provides a powerful tool for chestnut breeding programs and conservation genetic studies of Castanea species.
Hongwen Huang, Ying Wang, Zhonghui Zhang, Zhengwang Jiang, and Shengmei Wang
Shi-Ying Wang, William H. Carlson, and Royal D. Heins
Argeranthemum frutescens `Butterfly' and `Sugar Baby', Brachycome hybrid `Ultra', Helichrysum bracteatum `Golden Beauty', Scaevola aemula `New Wonder',Supertunia axillaris hybrids `Kilkenny Bells' and `Pink Victory', Sutera cordata `Mauve Mist' and `Snowflake', and Verbena hybrid `Blue' were grown in a glass greenhouse maintained at 20°C under seven different photoperiods (10-, 12-, 13-, 14-, 16-, 24-hr, and 4-hr night interruption). Black cloth was pulled at 1700 and opened at 0800 HR; incandescent lamps provided 2 μmol·m–2·s–1 to extend light hours to the designed photoperiods. Seedlings were pinched 3 days after transplant. Responses to photoperiod were clearly species-dependent. The tested species can be classified into three groups: 1) stem elongation and flowering were promoted in the long-day treatment (A. frutescens and S. axillaris hybrids), 2) only stem elongation was promoted in the long-day treatment (S. aemula, H. bracteatum, and B. hybrid), and 3) neither flowering nor stem elongation were affected by photoperiod (S. cordata and V. hybrid).
Shi-Ying Wang, William H. Carlson, and Royal D. Heins
The effect of 6 weeks of storage at 2.5, 5.0, 7.5, 10.0, or 12.5°C in a glass greenhouse was determined on 11 vegetatively propagated annual species. Fresh weight (total, shoot, and root) and height of 30 plants per species in each storage temperature were measured at the end of storage. Another 30 plants were transplanted into 15-cm pots (three plants per pot) and grown under natural light in a 20°C glass greenhouse for 3 weeks. Three species showed chilling injury or died during storage at ≤7.5°C. Plant height and shoot fresh weight at the end of storage for most species increased linearly as storage temperature increased. Storage temperature did not affect the net increase in height or weight significantly during recovery growth, except for plants that exhibited chilling injury at the end of storage.
Yiqi Zhen, Zuozhou Li, Hongwen Huang, and Ying Wang
Forty-eight kiwifruit cultivars and selections, representing more than 90% of total world kiwifruit production, were investigated using nine SSR markers to establish genetic identities, and evaluate genetic diversity and relatedness. These nine SSRs were polymorphic and a total of 213 alleles were detected, resulting in a mean number of 23.7 alleles per locus, ranging from nine to 38 alleles. One hundred and thirty-three alleles were found to be common to both A. chinensis and A. deliciosa, while 33 and 36 were specific to A. chinensis and A. deliciosa, respectively. In addition, 34 alleles were specific to one single genotype and provided a set of valuable alleles for cultivar identification. A single SSR locus UDK 96-414 could differentiate all 48 genotypes except two presumable clones. Mean number of alleles per locus (A), percentage of polymorphic loci (P), and direct count heterozygosity (Ho) assessed for each genotype over all loci revealed considerable differences among these 48 genotypes. On average, A = 2.6, P = 89.4% and Ho = 0.546 were found in A. chinensis cultivars, while A = 3.5, P = 97.0% and Ho = 0.671 in A. deliciosa cultivars. Consensus fingerprint profiling using SSR markers is a useful and reliable method for establishing genetic identities of kiwifruit cultivars and selections. It also improves evaluation effectiveness of genetic diversity and relatedness compared to RAPD markers.
Yan-xin Duan, Ying Xu, Ran Wang, and Chun-hui Ma
‘Akizuki’ (Pyrus pyrifolia Nakai) is a dominant Asian pear cultivar with gradually increasing cultivation area in Shandong province. However, this cultivar is found susceptible to cork spot disorder in recent years. In this study, we explored the physiological-biochemical mechanism of cork spot disorder in pear fruit, and investigated the effectiveness of spraying calcium (Ca), boron (B) solution or prohexadione calcium (P-Ca) on cork spot incidence. Cork spotted fruit had the characteristics of significantly larger fruit size with shorter fruit pedicels. Compared with normal fruit, cork spotted fruit had lower content of total soluble solids, soluble and reducing sugar, and vitamin C. In addition, cork spotted fruit accumulated much higher levels of N and Mg, and lower levels of K and P. However, Ca deficiency was not observed in cork spotted fruit, on the contrary, we determined high concentrations of Ca and free Ca2+ in disordered fruit. At the same time, the ratios of K/Ca, Mg/Ca, and (K+Mg)/Ca were significantly lower in cork spotted fruit as compared with normal fruit. Among all treatments, spraying with 3500 times dilution of P-Ca at 15-day intervals from 30 to 90 days after full bloom showed promise for reducing cork spot incidence in ‘Akizuki’ pear without affecting fruit quality attributes. This research herein reveals the physiological-biochemical characteristic of cork spot disorder, and implicates P-Ca as a potential tool to reduce cork spot incidence in Asian pear cultivar Akizuki.
Yu Bai, Ying Zhou, Xiaoqing Tang, Yu Wang, Fangquan Wang, and Jie Yang
The appropriate timing of bolting and flowering is one of the keys to the reproductive success of Isatis indigotica. Several flowering regulatory pathways have been reported in plant species, but we know little about flowering regulatory in I. indigotica. In the present study, we performed RNA-seq and annotated I. indigotica transcriptome using RNA from five tissues (leaves, roots, flowers, fruit, and stems). Illumina sequencing generated 149,907,857 high-quality clean reads and 124,508 unigenes were assembled from the sequenced reads. Of these unigenes, 88,064 were functionally annotated by BLAST searches against the public protein databases. Functional classification and annotation assigned 55,991 and 23,072 unigenes to 52 gene ontology (GO) terms and 25 clusters of orthologous group (COG) categories, respectively. A total of 19,927 unigenes were assigned to 124 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, and 80 candidate genes related to plant circadian rhythm were identified. We also identified a number of differentially expressed genes (DEG) and 91 potential bolting and flowering-related genes from the RNA-seq data. This study is the first to identify bolting and flowering-related genes based on transcriptome sequencing and assembly in I. indigotica. The results provide foundations for the exploration of flowering pathways in I. indigotica and investigations of the molecular mechanisms of bolting and flowering in Brassicaceae plants.