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  • Author or Editor: Qi Zhang x
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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.

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Paeonia ostii is recognized as an important oilseed tree peony species with potential as a raw material source for cosmetic and health care products, strong seed setting capacity, high seed oil yield, and abundant omega-3 polyunsaturated fatty acids. P. ostii, commonly called Fengdan, is widely cultivated in China. The cultivation method difference has an important influence on the oil-use feature, which is a key index for evaluating the quality of oilseed crops. This study aimed to select an optimal cultivation method to provide the first reference data for high-yield and high-quality seed oil harvesting and to facilitate the understanding of the quality difference in the formation mechanism of seed oil in cultivated P. ostii. This study selected five representative cultivation methods, open field cultivation, sunny slope cultivation, shady slope cultivation, understory intercropping cultivation, and high-altitude cultivation, and investigated the influence of cultivation method differences on the oil-use feature based on the three aspects of seed yield traits, oil yield, and fatty acid compositions. Six seed yield traits (fruit pod length, fruit pod width, fruit pod thickness, number of fruit pods per plant, 1000-grain weight, and seed yield per plant) and oil yield reached the maximum values of 7.75 cm, 6.99 cm, 1.57 cm, 11.33, 290.45 g, 85.8 g, and 30.41%, respectively, using the understory intercropping cultivation method. Fatty acid compositions were mainly identified as α-linolenic acid, linoleic acid, oleic acid, stearic acid, and palmitic acid, with significant content differences among different cultivation methods (P < 0.05). Functional component α-linolenic acid and total amounts of unsaturated fatty acids reached the maximum values of 46.85% and 65.23%, respectively, with high-altitude cultivation and understory intercropping cultivation. The seed yield traits, oil yield, and total amounts of unsaturated fatty acids were optimal with the understory intercropping cultivation method, whereas high-altitude cultivation was conducive to the accumulation of α-linolenic acid. Understory intercropping cultivation with appropriate altitude increases is recommended as a preponderant cultivation method for high-yield and high-quality seed oil harvesting for this crop.

Open Access

The branch number of plants is an important agronomic trait that directly influences the ornamental characters and production costs of ornamental plants. Shoot branching has always been a hot topic for Petunia hybrida. During our research, we isolated the homologous gene of narrow-leaf 1 (NAL1), denoted as PhNAL1. The expression level of PhNAL1 was higher in leaves and axils than in roots, stems, and flowers. Pertinent to shoot apex removal and 6-benzyladenine treatments, both interventions demonstrated a suppressive effect on the expression of PhNAL1. Through subcellular localization analysis, we found that PhNAL1 predominantly localized in the nucleus. By using RNA interference targeting PhNAL1, we induced a noticeable increase in branch number while concurrently reducing plant height of petunia. These findings demonstrate that PhNAL1 is involved in regulating branch development within petunia. This study provides genetic resources for the subsequent cultivation of new cultivars of petunia endowed with distinct branching characteristics.

Open Access

More axillary buds 1 (MAX1), initially identified in arabidopsis (Arabidopsis thaliana), is a key regulatory gene in strigolactone synthesis. CmMAX1, an ortholog of MAX1 was cloned from chrysanthemum (Chrysanthemum morifolium cv. Jinba). It had an open reading frame of 1611 bp and encoded 536 amino acid of P450 protein, with a conserved heme-binding motif of PFG × GPR × C × G, as well as PERF and KExxR motifs. The predicted amino acid sequence of CmMAX1 was most closely related to the MAX1 ortholog identified in lotus (Nelumbo nucifera), NnMAX1, with 55.33% amino acid sequence similarity. Expression analysis revealed there was no significant difference of CmMAX1 expression among various tissues. Phosphorus (P) deficiency significantly improved the expression levels of CmMAX1. Strigolactone, auxin, and cytokinin negatively regulated the expression of CmMAX1. Overexpression of CmMAX1 reduced the branch numbers of arabidopsis max1-1. These results suggest that CmMAX1 may be a candidate gene for reducing the shoot branching of chrysanthemum.

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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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Cell membranes play an integral role in freezing tolerance. The objectives of this study were to quantify polar lipids in cold-tolerant ‘Meyer’ zoysiagrass (Zoysia japonica) and cold-sensitive ‘Cavalier’ zoysiagrass (Zoysia matrella) and to evaluate their potential role in freezing tolerance. Grasses were acclimated outside and sampled once monthly between October and January to determine freezing tolerance and lipid composition in rhizomes. Lowest LT50s (temperature resulting in 50% survival) were observed in November for ‘Cavalier’ (−8.5 and −9.6 °C in 2005 and 2006, respectively) and December for ‘Meyer’ (−16.2 and −15.4 °C in 2005 and 2006, respectively). The most abundant lipids in zoysiagrass rhizomes were monogalactosyl diacylglycerol, digalactosyl diacylglycerol, phosphatidylcholine, phosphatidylethanolamine, and phosphatidic acid, which comprised 90% of the polar lipids. Differences in lipid contents and double bond indices (DBI) were detected between ‘Meyer’ and ‘Cavalier’ during cold acclimation, but there were no consistent relationships between lipid classes or DBI and freezing tolerance in zoysiagrass.

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Monoecious cucumber (Cucumis sativus L.) parents with high, medium, and low percentage of nodes with distillate flowers had a stronger effect on the percentage of gynoecious plants in F1 and F2 progenies than did degree of gynoecious expression in incompletely gynoecious parents. Highest percentages of gynoecious plants were obtained by using both gynoecious and monoecious parents with the highest level of distillate flowering tendency. According to our data, monoecious parents with a low percentage of distillate flowering nodes should be avoided when gynoeciousness is transferred to monoecious cultivars. Self-pollination of gynoecious F2 plants, requiring induction of staminate flowers by chemical treatment, was more effective in obtaining a high percentage of gynoecious plants in F3 progenies than selfing predominately gynoecious plants, or sibmating predominately gynoecious plants.

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A new sterile mutant designated pollen sterile (PS) found in pickling cucumber (Cucumis sativus L.) is characterized by normal corolla in staminate and pistillate flowers, normal fertility in the female, and absence of pollen in otherwise normal-appearing staminate flowers. All F1 plants from PS × male fertile (MF) sib-matings were MF, and F2 progeny segregated 3 MF: 1 PS. Sib-matings of PS segregates with sister MF segregates produced either 1 MF: 1 PS ratios or all normal plants. Thus, PS is controlled by a single recessive gene. The PS gene is not allelic to apetalous (ap), but was shown to be allelic to male sterile-2 (ms-2) and is designated ms-2 PS. It was not possible to determine possible allelic relationships between ms-2 PS and ms-1 because of strong male and female sterility of the available ms-1 material. F1 generations from gynoecious-PS and monoecious-PS crossed with monoecious, gynoecious (silver-ion treated), and hermaphroditic parents produced no PS plants and sex types did not influence PS levels in F2 progenies, indicating it is not possible to maintain the PS mutants through crosses with different cucumber sex types. It was not possible to change the expression of PS by applying cytokinin, IAA, or GA3, and there were no changes in response to temperature and fertilizer treatment. Unlike gynoecy, which is responsive to some external factors, PS is unresponsive. The results suggest that the use of PS in cucumber F1 hybrid seed production is not practical. Chemical names used: indole acetic acid (IAA), gibberellin (GA3).

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