Seashore paspalum (Paspalum vaginatum) is an important warm-season turfgrass distributed in tropical and coastal areas. It has excellent resistance to abiotic stresses, such as salinity, drought, and low temperature. However, the research on genetic diversity of local P. vaginatum collections from China is limited. In this study, the genetic diversity among 58 P. vaginatum accessions from four different provinces in China and four cultivars were assessed using simple sequence repeat (SSR) markers. The results indicated that a total of 45 alleles were detected by 19 polymorphic markers, with a range of 2 to 4 and an average of 2.4 alleles per marker. The genetic similarity coefficients between each pair of the 58 P. vaginatum accessions and four cultivars ranged from 0.51 to 1.00, with an average of 0.77. The range of variation of Shannon diversity index of each SSR marker was 0.047 to 1.075, with an average of 0.486. The polymorphic information content of each SSR marker varies from 0.016 to 0.577, with an average of 0.249. The results of cluster analysis and principal component analysis (PCA) showed that 58 P. vaginatum accessions and four cultivars were divided into four groups. These results provide the theoretical basis for the genetic diversity assessments and molecular marker–assisted breeding of P. vaginatum species.
Qing Shen, Hua Bian, Hai-yan Wei, Li Liao, Zhi-yong Wang, Xiao-yan Luo, Xi-peng Ding, Zhenbang Chen and Paul Raymer
Zhijun Zhang, Huaifeng Liu, Junli Sun, Songlin Yu, Wang He, Tianyuan Li and Zhao Baolong
The use of resistant rootstocks is an inevitable trend in the development and production of grapes (Vitis sp.). The present study analyzed differences in the metabolites in grape seeds of different rootstock combinations (1103P, 5C, SO4, 3309C, 140R, and control) grafted onto ‘Cabernet Sauvignon’ (CS) wine grape (Vitis vinifera) scions (control, CS/CS, self-rooted grafting vines) using liquid chromatography–mass spectrometry (LC-MS) and nontargeted metabolomic techniques. Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and orthogonal-partial least squares discriminant analysis identified 30 significant metabolites and 22 metabolic pathways in the seeds of CS that differed significantly from the control seeds. This study revealed that rootstocks influence metabolite concentrations and metabolic pathways (alanine–aspartate–glutamate pathway, arginine-proline pathway, and the tricarboxylic acid cycle) in the scion onto which they are grafted. The rootstocks increased the concentration of delphinidin-3-(6-acetylglucoside), peonidin 3-(6-p-coumarylglucoside), L-threonine, and D-tartaric in CS seeds. Appropriate rootstock combinations can be used to improve the quality of grape seeds by changing the concentrations of amino acids, organic acids, polyphenols, and vitamin B. This study provides a theoretical basis for selecting grape rootstocks and provides important insights for improving the quality of commercial products derived from grape seeds.
Santiago García-Martínez, Adrián Grau, Aranzazu Alonso, Pedro Carbonell, Juan Francisco Salinas, José Ángel Cabrera and Juan J. Ruiz
Jesús Gallegos, Juan E. Álvaro and Miguel Urrestarazu
The response of root growth in containers has been studied in recent decades. The objective was to evaluate the effect of four types of containers on root and shoot growth. The containers were two shapes, round and square, and in some containers, internal vertical walls (IVWs) were placed that increased the internal container surface area with two substrates: perlite and coir fiber. Seedlings of cucumber, pepper, and tomato were transplanted. Two experiments were performed: vegetative growth and drought stress by partial decapitation and a period without fertigation. After decapitation, preexisting and new leaf area, dry biomass or the leaves, and stem were measured. The results revealed that the type of container had no effect, nor were there significant differences between substrates. The containers with IVWs exhibited an increase in biomass and the root surface. The total contact surface with the substrate of the four container types was closely related to the recorded plant growth. Thus, IVWs not only decrease mechanical problems of roots by preventing spiralling but also favor the production of biomass in vegetable plants and substantially increase the root, enabling the plants to manage water deficit and potentially improve posttransplant stress.
Mingyue Bao, Minmin Liu, Qingxia Zhang, Tonglin Wang, Xia Sun and Jinguang Xu
Herbaceous peony (Paeonia lactiflora Pall.) is a well-known ornamental plant with abundant flower colors. However, our understanding of the underlying mechanisms of flower color formation is limited. In this study, a wild sample of herbaceous peony (collected from Heze, China) and eight cultivars with different colors were selected for experimental investigation. The Royal Horticultural Society Color Chart was used to determine flower color, and the anatomic structure; cell sap pH value; moisture content (MC); condensed tannin content (Ct); soluble sugar and soluble protein content of the petals; and content and composition of anthocyanin, flavonoids, and carotenoids in the petals were examined. 1) In the white, pinkish white, pale purple, purplish pink, and reddish purple cultivars, deeper color was associated with greater total amounts of anthocyanin (TA). Hypochromic effects were observed for kaempferol-7-O-glucoside (Km7G), myricetin-3-rhamnoside (My3R), and luteolin-7-O-glucoside (Lu7G). The accumulation of quercetin-3-O-glucoside (Qu3G) and lutein affected yellow color formation in the petals. 2) There are papillate epidermal cells in the petals of the wild P. lactiflora sample, ‘Lanyucangjin’, and ‘Dongjingnvlang’. 3) Cell sap pH and MC of the petals of white, pinkish white, pale purple, and purplish pink cultivars were greater than those of the purplish red and most of the reddish purple cultivars. 4) The Ct was greatest in the purplish red cultivars, whereas no condensed tannins were detected in the white, pinkish white, and pale purple cultivars. 5) There were no significant correlations among soluble sugar content, soluble protein content, and the other physiological indications.
Chunxian Chen and William R. Okie
Lisa Tang, Sukhdeep Singh and Tripti Vashisth
In the past decade, FL citrus industry has been struck by Huanglongbing (HLB), a disease caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas). Besides tree decline, HLB causes a sharp increase in mature fruit drop before harvest, leading to a substantial reduction in citrus production. The aim of the study was to provide insights in HLB-associated mature fruit drop. For HLB-affected ‘Valencia’ and ‘Hamlin’ sweet orange (Citrus sinensis), trees exhibiting severe symptoms (“severe trees”) had a significantly higher rate of mature fruit drop compared with mildly symptomatic ones (“mild trees”). Interestingly, dropped fruit were smaller than those still attached to tree branches regardless of the symptom levels of trees; overall, fruit of severe trees were smaller than mild trees. The result suggests a negative effect of HLB on fruit growth that may lead to a high incidence to drop subsequently at maturity. This possibility is further supported by the difference in immature fruit size as early as 2 months after bloom between severe and mild trees. Although HLB-triggered phloem plugging due to callose deposition in citrus leaves, which results in disrupted carbohydrate transport, has been documented in literature, the results of the histological analysis demonstrated no consistent pattern of callose deposition in the mature fruit pedicel in relation to the drop incidence. Additionally, sugar concentration in juice was not significantly different between dropped and attached fruit, providing evidence that carbohydrate shortage is not the case for dropped fruit and thus not the predominant cause of HLB-associated mature fruit drop. Notably, the midday water potential was significantly lower for severe than mild trees during the preharvest period (2 weeks before harvest of the current crop) in late March, which was also the second week after full bloom of return flowering. This suggests that altered tree water status due to HLB might limit fruit growth during the initial stage of fruit development (immediately after flowering) and/or increase the incidence of mature fruit abscission, leading to elevated preharvest fruit drop. Together, the results suggest that in the presence of HLB, strategies to increase fruit size and minimize additional stresses (especially drought) for the trees may improve mature fruit retention.
Sean M. Campbell, Brian J. Pearson and S. Christopher Marble
Butterfly pea (Clitoria ternatea) is a unique perennial and leguminous plant that produces brightly colored flowers that can be used as a pH-dependent natural food colorant in culinary and cosmetic preparations. Butterfly pea is commonly propagated from seed. Because of the increased interest in its commercial applications, effective production techniques are necessary to ensure consistent and successful commercial production. The objective of this research was to determine the influence of the substrate type and temperature on butterfly pea germination. Two substrate types (rockwool and commercial soilless substrate mix) and three temperatures (70, 80, and 90 °F) were evaluated to determine their effects on germination of butterfly pea seed. Collected and calculated germination data included germination capacity (G), mean germination time (MT), coefficient of variation of the germination time (cv t), mean germination rate (MR), uncertainty of the germination process (U), and synchrony of the germination process (Z). Differences were observed among substrate temperatures for the MT, cv t, and MR values, with germination greater at both 70 and 80 °F than at 90 °F. Similarly, significant differences among substrate types were observed for the G, MT, cv t, and MR values, with germination of seeds in rockwool outperforming seeds in soilless substrate mix. Because of the high priority for successful and uniform germination in commercial plant production operations, the results suggest that commercial germination of butterfly pea would be best in rockwool at 70 °F. Results of this study can be used for the commercial production of butterfly pea, for which propagation from seed is the primary means of plant production.
Xiongwen Chen and Hua Chen
Chinese Torreya (Torreya grandis cv. Merrillii) is an important economic tree in China, but there are limited studies on its seed production. We analyzed the patterns of historical seed production at two major sites (Zhaojiazhen and Jidongzhen) for Chinese Torreya from different perspectives. The results indicated that there were no 3-year or multiyear cycles in its seed production. A positive correlation existed between the average seed production and the average annual air temperature in 5 or 10 years at both study sites. There was no trend of the increasing coefficient of variance (cv) in seed production, but the cv generally increased before 1975, and became flat after that time. Frequency power law existed in seed production at both sites, but Taylor’s Law existed only at Zhaojiazhen. The multiscale entropy decreased with time scales, and the patterns were similar at both sites. Our research results provide a new understanding of seed production for Chinese Torreya.
Ariana Torres, Petrus Langenhoven and Bridget K. Behe
The domestic market for melons, Cucumis melo L., has not been well characterized. The 2011 cantaloupe-related foodborne illness outbreak reduced melon production by 32%, and per capita consumption of cantaloupe and honeydew melons has not recovered. Our objective was to profile and characterize consumer segments of individuals who purchased melons in the 3 months before the survey. Responses from 1718 participants were analyzed by consumption volume and subjected to cluster analysis based on importance of melon attributes. Heavy and moderate consumers preferred local melons over imported. The top four melon attributes were flavor, freshness, ripeness, and sweetness. As consumption increased, consumers placed more importance for their diets. The heaviest consumption group accounted for 22% of the market, and consumed nearly three times the melon servings per month compared with the moderate consumer, and nearly 10 times the servings of the light consumption group. Cluster analysis produced three distinct clusters. Cluster 1 was the most promelon in attitudes and consumption, as well as general health interest, craving sweet food, food pleasure, and variety seeking in foods. The largest segment was cluster 3 and was the ideal group for future targeting of marketing and advertising campaigns for increasing the melon market share with their intermediate consumption and promelon attitudes. Last, members of cluster 2 consumed the lowest amount of melons, spent the least on melons, and traveled the fewest number of miles to purchase them, relative to the other two segments.