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  • Author or Editor: Qi Wang x
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Many golf courses and turfgrass managers use recycled water, which contains high salts, as part or a sole irrigation source to lower costs and comply with governmental restrictions on water use. High salinity negatively affects turfgrass performance. Using salt-tolerant species or cultivars is one the most effective methods to address salinity problems. Twenty-six commercially available creeping bentgrass (Agrostis stolonifera) cultivars were evaluated for salt tolerance during in vitro germination on 1% agar media supplemented with NaCl at 0, 5, 10, 15, or 20 g·L−1 at 25/15 °C (day/night) under fluorescent light (36 μmol·s−1·m−2) with an 8- to16-h photoperiod. Significant variations in salinity tolerance were observed among the cultivars. Final germination rate (FGR, %) and daily germination rate (DGR, %/d) decreased linearly or quadratically as salinity levels increased. ‘Declaration’, ‘Seaside II’, ‘T-1’, and ‘Bengal’ were the most salt-tolerant, requiring salt levels at or greater than 16.0 and 10.0 g·L−1, respectively, to reduce FGR and DGR by 50%. In contrast, ‘Tyee’, ‘Kingpin’, and ‘SR1150’ required average salinity levels of 11.6 and 6.5 g·L−1 to cause 50% reduction in FGR and DGR, respectively, showing that they were the least salt-tolerant cultivars. The largest difference between FGR (1.9%) and DGR (26.2%) reduction under saline conditions was observed at 5 g·L−1, indicating that DGR was more sensitive to salinity changes than FGR. Therefore, DGR might be a more reliable method to be used for salt selection.

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Salinity tolerance of five buffalograss [Buchloe dactyloides (Nutt.) Englem.] cultivars (Texoka, Cody, Bison, Sharp's Improved II, and Bowie) and three blue grama [Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths] ecotypes (‘Lovington’, ‘Hachita’, and ‘Bad River’) was determined during in vitro seed germination and vegetative growth in a hydroponic system. Seeds were germinated on 0.6% agar medium supplemented with NaCl at 0, 5, 10, 15, and 20 g·L−1. Salinity reduced the final germination rate (FGR) and daily germination rate (DGR). Similarly, shoot dry weight (SDW), longest root length (LRL), and percentage of green tissue (PGT) of mature grasses declined with increasing salinity levels (NaCl = 0, 2.5, 5, 7.5, and 10 g·L−1). However, root dry weight (RDW) was not significantly affected by salinity. Blue grama exhibited a lower reduction in FGR and DGR than buffalograss at salinity levels lower than 10 g·L−1. Germination of all buffalograss cultivars and ‘Hachita’ blue grama was inhibited at salinity levels of 15 and 20 g·L−1 NaCl. However, buffalograss was more salt-tolerant than blue grama at the vegetative growth stage. Variations of salinity tolerance were observed within buffalograss cultivars and blue grama ecotypes, especially during the seed germination stage. Overall, buffalograss appeared to be salt-sensitive during germination but moderately salt-tolerant at the mature stage. However, blue grama was more salt-tolerant at the germination stage than the mature stage. Noticeable differences in salinity tolerance were observed between different germplasms. Therefore, salt tolerance of buffalograss and blue grama may be improved through turfgrass breeding efforts.

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Prairie junegrass (Koeleria macrantha) is a perennial, cool-season, native grass that has shown potential for use as a turfgrass species in the northern Great Plains; however, limited information is available on its salt tolerance. In this study, salinity tolerance of four junegrass populations from North America (Colorado, Minnesota, Nebraska, and North Dakota) and two improved turf-type cultivars from Europe (‘Barleria’ and ‘Barkoel’) was evaluated and compared with kentucky bluegrass (Poa pratensis), perennial ryegrass (Lolium perenne), sheep fescue (Festuca ovina), hard fescue (F. brevipila), and tall fescue (F. arundinacea). Salinity tolerance was determined based on the predicted salinity level causing 50% reduction of final germination rate (PSLF) and daily germination rate (PSLD) as well as electrolyte leakage (EL), tissue dry weight (DW), and visual quality (VQ) of mature plants. All populations of prairie junegrass showed similar salt tolerance with an average of PSLF and PSLD being 7.1 and 5.3 g·L−1 NaCl, respectively, comparable to kentucky bluegrass and hard and sheep fescue but lower than tall fescue and perennial ryegrass. Larger variations were observed in VQ in the junegrasses compared with EL and DW, in which ‘Barleria’ from the European population showed the highest VQ, following two salt-tolerant grasses, tall fescue and sheep fescue. Nebraska population was the least salt-tolerant within the species but still exhibited similar or higher tolerance than kentucky bluegrass and perennial ryegrass cv. Arctic Green. Overall, junegrass was more salt-sensitive during germination but more tolerant to salinity when mature. Salinity tolerance of junegrass may be further improved through turfgrass breeding because salinity tolerance varied in different populations.

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Salinity tolerance of 12 turfgrasses in four groups, creeping bentgrass (Agrostis stolonifera L.), fescues (Festuca spp.), kentucky bluegrass (Poa pratesis L.), and alkaligrass [Puccinellia distans (Jacq.) Parl.], was evaluated using three germination methods. Seeds were germinated on 1% agar medium, on germination paper, or in a hydroponic system under salinity levels of 0, 5, 10, 15, or 20 g·L−1 NaCl. Germination rate and seedling growth of each grass were determined. Salinity reduced the final germination rate (FGR), daily germination rate (DGR), and seedling leaf area (LA) in all tests. On agar medium, no significant difference in salinity tolerance was observed among the four turf groups; however, ‘Turf Blue’ kentucky bluegrass with a corn starch-based coating (coated ‘Turf Blue’) showed a significant higher salinity tolerance than the uncoated one. Using germination paper, creeping bentgrass required the highest salinity level to cause 50% reduction in FGR followed by alkaligrass, fescues, and kentucky bluegrass. Kentucky bluegrass required the lowest salinity level (9.5 g·L−1) to reduce DGR by 50%. With the hydroponic system, alkaligrass required a salinity level of 26.3 g·L−1 to reduce FGR by 50%, the highest among the four groups. Alkaligrass showed again the highest salinity tolerance with an average of 12.7 g·L−1 needed to reduce LA by 50%. Among the grasses, coated ‘Turf Blue’ kentucky bluegrass, ‘Declaration’ creeping bentgrass, and ‘Fults’ alkaligrass showed the highest salinity tolerance when evaluated on agar medium, on germination paper, or in the hydroponic system, respectively. The present study determined the salinity tolerance of 12 turfgrasses at seed germination and early seedling growth stages and showed that the germination method was a factor affecting the evaluation result and it should be considered in a seed germination test of turfgrass for salinity tolerance.

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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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Thirty herbaceous peony (section Paeonia of the genus Paeonia) cultivars were divided into four groups (no fragrance, light fragrance, medium fragrance, or intense fragrance) based on their sensory evaluation scores. Using dynamic headspace sampling (DHS) and automatic thermal desorption–gas chromatography/mass spectrometry (ATD-GC/MS), 130 volatile organic components were detected in these 30 cultivars and a total of 72 compounds were identified as scent components. The main compounds were phenylethyl alcohol, β-caryophyllene, linalool, (R)-citronellol, and nerol. Selecting α-pinene as the standard, the volatile components of these cultivars were quantitatively analyzed. By combining the sensory evaluation scores and the results of quantitative analysis, we found that ‘Going Bananas’, ‘Cream Delight’, ‘Zhu Sha Pan’, ‘Qiao Ling’, ‘Duchess de Nemours’, and ‘Yang Fei Chu Yu’ displayed an intense fragrance and, thus, had relatively high commercial value for the flower fragrance industry. ‘Red Magic’, ‘Joker’, ‘Fairy Princess’, ‘Lovely Rose’, ‘Carina’, and ‘Etched Salmon’ were excluded from the hierarchical cluster of aromatic compounds and the analysis of fragrance patterns because of the low amount of fragrance they released and poor sensory evaluation results. Based on a cluster analysis, assessment of the major aromatic compounds, and the results of sensory evaluation, the remaining 24 cultivars were divided into five fragrance patterns for the first time: woody scent [cluster I (major fragrance β-caryophyllene)], fruity scent [cluster II (phenylethyl alcohol)], lily scent [cluster III (linalool)], rose scent {cluster IV [(R)-citronellol]}, and an orange blossom scent [cluster V (nerol)].

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Abscisic acid (ABA) is an essential phytohormone that regulates plant growth and development, particularly in response to abiotic stress. The ABA receptor PYR/PYL/RCAR (PYL) family has been identified from some plant species. However, knowledge about the PYL family (VvPYLs) in grape (Vitis vinifera) is limited. This study aims to conduct genome-wide analyses of VvPYLs. We successfully identified eight PYL genes from the newest grape genome database. These VvPYLs could be divided into three subfamilies. Exon-intron structures were closely related to the phylogenetic relationship of the genes, and PYL genes that clustered in the same subfamily had a similar number of exons. VvPYL1, VvPYL2, VvPYL4, VvPYL7, and VvPYL8 were relatively highly expressed in roots. VvPYL1, VvPYL3, VvPYL7, and VvPYL8 were expressed in response to cold, salt, or polyethylene glycol stress. VvPYL6 was up-regulated by cold stress for 4 hours, and the expression of VvPYL2 was 1.74-fold greater than that of the control under cold stress. VvPYL8 was up-regulated 1.64-, 1.83-, and 1.90-fold compared with the control when treated with salt, PEG, or cold stress after 4 hours, respectively. Additionally, abiotic stress-inducible elements exist in VvPYL2, VvPYL3, VvPYL7, and VvPYL8, indicating that in these four genes, the response to abiotic stress may be regulated by cis-regulatory elements. The transcriptional levels of VvPYL1 and VvPYL8 significantly increased from fruit set to the ripening stage and decreased in the berry when treated by exogenous ABA. The eight VvPYL genes have diverse roles in grape stress responses, berry ripening, or development. This work provides insight into the role of VvPYL gene families in response to abiotic stress and berry ripening in grape.

Open Access