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Zhang Qixiang

On the basis of investigating pollination habits of 45 cultivars of Mei Hua, interspecific hybridization between Mei Hua and apricot (Prunus armeniaca). David's peach (P. davidiana) as well as siberian apricot (P. sibirica) were made from 1982 to 1991. With total number of pollination flower 17,050, 168 hybrid seed and 75 hybrid seedlings were obtained. Embryo culture in vitro was used for undeveloped young hybrid embryos. Test of freezing resistance both in artificial freezing and in overwintering for the hybrid seedlings showed that there were 5 hybrids with double and nice flower to be very hardy to low temperature. They were able to tolerate as low as -35C for 30 days in open ground, and now they were planted in northwest China's Gansu province and northeast China's Liaonin province without cold injury.

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Dongyan Hu*, Zuoshuang Zhang, Donglin Zhang and Qixiang Zhang

Ornamental peach (Prunus persica (L.) Batsch) is native to China. The ornamental value of peach is gaining popularity for its use in urban landscape and everyday gardens. However, the genetic relationship among ornamental peach cultivars is not clear, which limits the further studies of its molecular systematic. A sample of 51 cultivars of ornamental peach, originated from P. persica and Prunus davidiana, had been studied by using AFLPs. All samples were collected from China, Japan, and the US. A total of 275 useful markers between 75 to 500 base pairs were generated from 6 EcoRI/MseI AFLP primer combinations. Among them, 93% of bands were polymorphic markers. Total markers for each cultivar ranged form 90 to 140, and the average number of markers for each cultivar was 120. Two distinguished clad generated from PAUP-UPGMA tree. P. davidiana, as a species, was apparently an out-group to P. persica, which implied that P. davidiana was far away genetically from ornamental peach (P. persica). Within P. persica clad, 15 out of 17 upright ornamental peach cultivars in this study were grouped to one clad, which indicated cultivars that with upright growth habit had close genetic relationship. Five dwarf cultivars were grouped to one clad, with 81% bootstrap supported. The genetic relationships between these five dwarfs were much closer than any other cultivars, and showed that they probably derived from the similar gene pool. The results demonstrated that AFLP are powerful markers for revealing genetic relationships in ornamental peach. The genetic relationships among ornamental cultivars established in this study could help future ornamental peach germplasm identification, conservation, and new cultivars development.

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Dongyan Hu, Zuoshuang Zhang, Donglin Zhang, Qixiang Zhang and Jianhua Li

Ornamental peach (Prunus persica (L.) Batsch) is a popular plant for urban landscapes and gardens. However, the genetic relationship among ornamental peach cultivars is unclear. In this report, a group of 51 ornamental peach taxa, originated from P. persica and P. davidiana (Carr.) Franch., has been studied using AFLPs. The samples were collected from China, Japan, and US. A total of 275 useful markers ranging in size from 75 to 500 base pairs were generated using six EcoRI/MseI AFLP primer pairs. Among them, 265 bands were polymorphic. Total markers for each taxon ranged from 90 to 140 with an average of 120. Two clades were apparent on the PAUP–UPGMA tree with P. davidiana forming an outgroup to P. persica, indicates that P. davidiana contributed less to the ornamental peach gene pools. Within P. persica clade, 18 out of 20 upright ornamental peach cultivars formed a clade, which indicated that cultivars with upright growth habit had close genetic relationship. Five dwarf cultivars were grouped to one clade, supported by 81% bootstrap value, indicating that they probably derived from a common gene pool. These results demonstrated that AFLP markers are powerful for determining genetic relationships in ornamental peach. The genetic relationships among ornamental cultivars established in this study could be useful in ornamental peach identification, conservation, and breeding.

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Dongyan Hu, Donglin Zhang, Zuoshuang Zhang, Qixiang Zhang and Jianhua Li

Ornamental peach [Prunuspersica (L.) Batsch.] is a well-known ornamental plant for the garden. However, the genetic relationship among ornamental peach cultivars is not clear, which limits further studies of its molecular systematics and breeding. A group of 16 taxa of ornamental peach, originated from Prunuspersica and Prunusdavidiana (Carr.) Franch., had been studied using AFLPs and ISSRs. A total of 243 useful markers between 75 to 500 base pairs were generated from six EcoRI/MseI AFLP primer combinations (ACC/CAT, AGG/CAT, ACT/CAT, ACC/CTC, AGG/CTC, and ACT/CTC). The average readable bands were 41 per primer combination. Among them, 84% of the bands were polymorphic markers. A total of 132 useful markers between 300 to 1400 base pairs were generated from 10 ISSR primers (UBC818, UBC825, UBC834, UBC855, UBC817, UBC868, UBC845, UBC899, UBC860, and UBC836). The mean reliable bands were 14 per primer. Among them, 62% of the bands were polymorphic markers. Both methods generated very similar phenograms with consistent clades. From these results we concluded that AFLP and ISSR analysis had a great potential to identify ornamental peach cultivars and estimate their phylogeny. The application of these molecular techniques may elucidate the hierarchy of ornamental peach taxa.

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Jiuxing Lu, Weiru Yang and Qixiang Zhang

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.

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Ying Kong, Ming Sun, Hui-tang Pan and Qi-xiang Zhang

Floral scents emitted from eight cultivars of cut lily flowers (Lilium) were analyzed. Floral volatiles were collected by headspace adsorption on sorbent tubes and analyzed by gas chromatography–mass spectrometry (GC/MS) using a direct thermal desorption. Fifty volatile compounds were identified. Nine compounds were detected in all lilies, whereas 20 compounds were detected in all scented lilies. The results revealed that non-scented lilies emitted trace amounts of volatile compounds, whereas scented lilies emitted high levels of volatile compounds. Monoterpenoids and benzenoids were the dominant compound classes of volatiles emitted from scented lilies. Myrcene, (E)-β-ocimene, linalool, methyl benzoate, and ethyl benzoate were the major compounds of the aroma of scented lilies; 1,8-cineole was also a major compound in the two scented oriental × trumpet hybrid lilies. Scent emissions occurred in a circadian rhythm with higher levels of volatiles emitted during the night. Lilium ‘Siberia’ was selected as a model to investigate the source of the emissions. GC/MS analysis of four flower parts and neutral red staining revealed that tepals were the source of floral scent.

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Le Luo, Chao Yu, Xuelian Guo, Huitang Pan and Qixiang Zhang

Rosa laxa is widely distributed in the Xinjiang Uygur Autonomous Region of China and is highly adaptable and rich in variation. In this study, we investigated the morphology, habitats, and palynomorphology of R. laxa botanical varieties from Xinjiang, China. In addition to R. laxa var. laxa, there were three other botanical varieties of R. laxa growing in southern Xinjiang, including var. mollis, var. kaschgarica, and var. tomurensis. Together, these four botanical varieties exhibited morphological variation, mainly in the morphology of prickles and the glandular trichome and in flower color. The pollen grains of the R. laxa botanical varieties, all medium in size (21.77–48.39 μm), came in three shapes: perprolate, prolate, and subspheroidal. Their pollen exine sculptures were characterized by either a striate-perforation pattern or striate pattern, but perforation varied in terms of diameter and density and striae varied in depth and density. Palynomorphological assessment showed that three types of evolution, i.e., primitive, transitive, and evolved, were present among R. laxa botanical varieties, and pollen dimorphism was observed in the same botanical variety. Perprolate pollen with a dense striate pattern was the most evolved type. Based on morphological and palynomorphological investigations, var. tomurensis was considered to be the most evolved one among the studied botanical varieties.

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Tao Wang, Ruijie Hao, Huitang Pan, Tangren Cheng and Qixiang Zhang

Mei (Prunus mume) is widely cultivated in eastern Asia owing to its favored ornamental characteristics and its tolerance for low temperatures. Reverse transcription quantitative real-time polymerase chain reaction (qRT-PCR) is a widely used method for gene expression analysis, requiring carefully selected reference genes to ensure data reliability. The aim of this study was to identify and evaluate reference genes for qRT-PCR in mei. Ten candidate reference genes were chosen, and their expression levels were assessed by qRT-PCR in four sample sets: 1) flowering mei; 2) mei undergoing abiotic stress; 3) different genotypes of Prunus species; and 4) all mei samples. The stability and suitability of the candidate reference genes were validated using commercially available software. We found that protein phosphatase 2A-1 (PP2A-1) and PP2A-2 were suitable reference genes for flowering with ubiquitin-conjugating enzyme E2 (UBC) also being suitable for different genotypes of Prunus species. UBC and actin (ACT) were most stably expressed under abiotic stress. Finally, the expression of an AGAMOUS homolog of Arabidopsis thaliana (PmAG) and a putative homolog of Group 2 late embryogenesis abundant protein gene in A. thaliana (PmLEA) were assessed to allow comparisons between selected candidate reference genes, highlighting the importance of careful reference gene selection.

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Xuejuan Chen, Ming Sun, Jianguo Liang, Hui Xue and Qixiang Zhang

Chrysanthemums have beautiful flowers with high ornamental value and rich genetic diversity. Amplified fragment length polymorphism (AFLP) markers were used to detect the relationships among 12 wild accessions and 62 groundcover chrysanthemum cultivars. Nineteen EcoRI/MseI primer combinations revealed 452 informative polymorphic bands with a mean of 23.8 bands and 71.5% polymorphic rate per primer pair. Jaccard’s coefficient of similarity varied from 0.64 to 0.89, indicating much genetic variation in chrysanthemums. The 74 accessions were classified into two major groups by unweighted pair group method with the arithmetic averages (UPGMA). The dendrogram showed that AFLP variability was closely correlated with both geographic distribution and traditional classification of the wild accessions. Among all accessions, genetic relationship was the most relevant factor in AFLP-marker clustering, whereas petal type was also informative. AFLP technology could be very efficient for discriminating species of chrysanthemum and its related genera and reconstruct their genetic relatedness.

Open access

Le Luo, Yichi Zhang, Yingnan Wang, Tangren Cheng, Huitang Pan, Jia Wang and Qixiang Zhang

Gesnariad (Primulina yungfuensis) is a popular houseplant species, native to southwest China. However, stunting frequently occurs as a result of limited knowledge about the growth requirements of this plant. Understanding water and fertilizer requirements of gesnariad are important for effective large-scale greenhouse cultivation. Using a response surface methodology (RSM) based on a rotatable central composite design (RCCD; half implementation), a pot experiment was performed in a natural-light greenhouse from June to Sept. 2014. The study assessed the interaction between irrigation volume (W) and nitrogen (N), phosphorus (P), and potassium (K) fertilizer rates on plant height, crown diameter, number of leaves, single leaf area, and fresh weight. Results showed that W had a significant positive effect on plant height, crown diameter, single leaf area, and fresh weight. Furthermore, P fertilization resulted in increased leaf number. Combined P and K fertilization reduced individual leaf area, whereas combined N and P fertilization reduced fresh weight. By analyzing the multiobjective decision-making model, we found that a combination of 100.2 mL water, 3.6 mmol·L−1 N, 0.10 mmol·L−1 P, and 1.2 mmol·L−1 K could be used to achieve optimum growth of gesnariad.