The effects of preharvest methyl jasmonate (MJ) application on fruit quality, flavonoid content and antioxidant capacity (ORAC) in black raspberry cv. Jewel (Rubus occidentalis L) were studied under field conditions. Raspberries treated with 0.1 mm methyl jasmonate had 20% higher soluble solids content, 20% higher total sugars, 16% higher fructose, 34% higher glucose and 30% lower titratable acids, 31% lower malic acid and 17% lower citric acid than untreated fruit. El-lagic acid, quercetin 3-glucoside, kaempferol 3-glucoside, kaempferol 3-glucuronide, cyanidin 3-glucoside and cyaniding 3-rutinoside were found in raspberry fruit extract. Cyanidin 3-rutinoside was the most dominant anthocyanin and was the major contributor to antioxidant activity in Jewel raspberries. MJ treatments significantly enhanced the content of anthocyanins by 92%, total phenolics by 53%, flavonoids by 98% and the antioxidant capacities by 74% in the fruit. The ORAC value was positively correlated with anthocyanins and total phenolics. In this study, the correlation coefficient for ORAC (y) vs anthocyanins (x) was 0.977 (y = 0.056x + 27.874), and that for ORAC (y) vs. total phenolics (x) was 0.988.
Huiling Wang, Wei Wang, Weidong Huang, and Haiying Xu
Salicylic acid (SA) as a plant signal molecule plays an important regulatory role in stimulating the accumulation of plants’ defensive compounds. Numerous studies have shown its regulating effects on the biosynthesis of flavonoids. However, the controlling mechanism needs to be made clear further. Here, Vitis vinifera L. ‘Cabernet Sauvignon’ cell suspension cultures were treated with SA and its synthesis inhibitor paclobutrazol (Pac) to investigate their effects on flavonoid biosynthesis. The accumulation of gene transcripts and proteins of flavonoid biosynthesis pathway enzymes, including chalcone synthase (VvCHS), chalcone isomerase (VvCHI), dihydroflavonol 4-reductase (VvDFR), and anthocyanidin synthase (VvANS), were detected using real-time polymerase chain reaction (RT-PCR), quantitative polymerase chain reaction (qPCR), and western-blotting techniques. The results showed that treatment with exogenous SA at the proper concentration enhanced the production of flavonoids such as anthocyanins and proanthocyanidins (PAs) inside the suspension-cultured cells. The induction of anthocyanins and PAs was found to be time course-dependent. The mRNA and protein accumulation of VvCHS, VvCHI, VvDFR, and VvANS in the treatment system were enhanced too, and the changes were observed concomitantly. Treatment of Pac inhibited the induction of the accumulation of gene transcripts and proteins in accordance with the decreased accumulation of flavonoids. These results suggest that exogenous SA could induce both transcript and protein accumulation of flavonoid biosynthesis-related enzymes and in turn enhance the accumulation of flavonoid compounds such as anthocyanins and PAs in suspension-cultured grape cells.
Fan Cao, Yunchu Wei, Xinwang Wang, Yongrong Li, and Fangren Peng
To describe the influence of different pecan seedling rootstocks on drought stress resistance, 12 rootstocks of ‘87MX1-2.2’, ‘87MX5-1.7’, ‘Elliott’, ‘Frutoso’, ‘Giles’, ‘Major’, ‘Moore’, ‘Peruque’, ‘Posey’, ‘Riverside’, ‘San Felipe’, and ‘VC1-68’ were selected as rootstock treatments for grafting. In addition, the experimental materials for the grafted young ‘Pawnee’ tree treatments included the pressure-volume technique (PV technique) and cutting shoot transpiration methods to plot the PV and the cutting shoot transpiration curves, and the parameters calculated from the two curves were used to analyze the data produced by the subordinate function and cluster dendrogram methods. The results revealed that the different seedling rootstock treatments influenced the ‘Pawnee’ grafted trees to varying degrees on aspects of drought resistance, the ability to save water, the modulation of osmosis, and the sensitivity of the stomatal response. The order of drought tolerance for these different pecan seedling rootstock treatments from high to low was as follows: ‘Posey’, ‘Peruque’, ‘Riverside’, ‘87MX5-1.7’, ‘VC1-68’, ‘Elliott’, ‘87MX1-2.2’, ‘San Felipe’, ‘Moore’, ‘Major’, ‘Giles’, and ‘Frutoso’.
Xiaoming Wang, Changzhu Li, Shijun Tang, and Wei Tang
Chestnut (Castanea mollissima Bl.) is a popular nut in Chinese and International market. However, storage of chestnut is difficult. In this study, the relationships of respiration rate, metabolic pathway, key enzymatic activities, metabolites, and membrane peroxidation with chestnut rotting during storage at room temperature (25 °C) and low temperature (0–3 °C) were investigated. The results show that the respiration rate of chestnut gradually decreases during storage at room temperature. Under the lower temperature, the respiration rate reduced 67.53% within 1 day, then gradually increased. Compared with room temperature, the lower temperature also significantly inhibited glycolysis, maintained higher level of tricarboxylic acid cycling, and reduced the conversion of pyruvate to ethanol and lactate. In addition, chloramphenicol acetyltransferase activities were inhibited while superoxide dismutase activities were high under the lower temperature, which resulted in the reduction of membrane peroxidation. Subsequently, the chestnut rotting rate was significantly reduced. In conclusion, the primary reason for chestnut rotting is the reduction of proper physiologic function and then bacteria and pathogen infection. Chestnut rotting rate during storage can be significantly reduced through an appropriate environment and new techniques and chemicals.
Wei Zhou, Hong Wang, De-Zhu Li, Jun-Bo Yang, and Wei Zhou
Luculia pinceana Hook. (Rubiaceae) is a typical distylous species with dimorphic and long-styled monomorphic populations. Within this study, we developed 13 microsatellite markers from L. pinceana using a modified biotin–streptavidin capture method. Polymorphism of each locus was assessed in 30 individuals from four dimorphic populations and one monomorphic population. The average allele number of these microsatellites was 4.153 per locus ranging from three to seven. The observed and expected heterozygosities were from 0.040 to 0.840 and from 0.571 to 0.769, respectively. Additionally, all 13 identified microsatellite markers were successfully amplified in its related species, L. yunnanensis, 10 of which showed polymorphism. These microsatellite markers could provide a useful tool for further study of the breeding system and the population genetic structure in this species and within other Luculia species.
Ting Min, Li-Fang Niu, Jun Xie, Yang Yi, Li-mei Wang, You-wei Ai, and Hong-xun Wang
NAC transcription factors have been characterized in numerous plants, and the NAC gene has been shown to be involved not only in plant growth and development, but also in plant responses to abiotic and biological stresses, such as drought, high salinity, low temperature, and anaerobic/hypoxic stress. Creating an environment of anaerobic/hypoxic stress has been shown to be one of the effective storage methods for delaying the browning of fresh-cut lotus (Nelumbo nucifera) root. However, whether NAC is associated with lotus root browning under anaerobic stress has not been studied. In this study, vacuum packaging (VP; anaerobic/hypoxic stress) effectively delayed the browning of fresh-cut lotus root. The changes in the expressions of NnPAL1, NnPPOA, and NnPOD2/3 were consistent with phenylalanine aminolase, polyphenol oxidase (PPO), and peroxidase (POD) enzyme activity changes and lotus root browning. Using RNA sequencing, five NnNAC genes were isolated and studied. Transcriptional analysis indicates that the NnNAC genes showed different responses to VP. The expressions of NnNAC1/4 were inhibited by VP, which was consistent with the observed change in the degree of fresh-cut lotus root browning. However, NnNAC2 messenger RNA (mRNA) levels were upregulated, and the expressions of NnNAC3/5 showed no clear differences under different packaging scenarios. Thus, NnNAC1/4 were identified as promising candidates for further transcriptional regulation analysis in lotus root to understand more fully the molecular mechanism of browning under anaerobic/anoxic stress.
Ting Min, En-chao Liu, Jun Xie, Yang Yi, Li-mei Wang, You-wei Ai, and Hong-xun Wang
Ethylene response factor (ERF) genes have been involved in responses to biotic and abiotic stress, including hypoxia and anaerobic stress. Vacuum packaging (a typical anaerobic stress) is an effective storage method used to delay browning of fresh-cut lotus root (Nelumbo nucifera). In model plants, ERF genes have been identified as responsive to hypoxia. Whether ERF is associated with browning of vacuum-packaged lotus root has not been studied. The effects of vacuum packaging on browning, phenolic content, the enzyme activity of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD), and PPO, PAL, POD, and ERF genes expression in fresh-cut lotus root were studied. Downregulation of NnPAL1, NnPPOA, and NnPOD2/3 attributable to vacuum packaging coincided with increased related enzyme activities and the degree of browning of fresh-cut lotus root. The expression patterns of NnERF4/5 were consistent with the changes in NnPAL1, NnPPOA, and NnPOD2/3 gene expression. It has been proposed that NnERF4/5 could have be important regulators of fresh-cut lotus root browning, and that the relationships of NnERF4/5 and NnPAL1, NnPPOA, and NnPOD2/3 should to be studied further.
Han Xu, Cuihua Bai, Wei Wang, Changmin Zhou, Luwei Zhu, and Lixian Yao
Free amino acid (FAA) profile is an important indicator of the quality of fruit and fruit product. Foliar nutrient diagnosis has been used for crop yield prediction for decades but not for fruit quality evaluation. Concentrations of 11 leaf nutrients including N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, and B at stages of terminal shoot maturation and fruit development and fruit FAA profile at harvest were examined in longan in South China. The relation between leaf nutrient and fruit FAA was then investigated by multiple stepwise regression analysis. Foliar N content was greatest among the nutrients among the detected elements at both stages. Twenty-nine FAAs were determined in longan flesh, with alanine (19.9%), γ-aminobutyric acid (17.5%), glutamic acid (15.2%), and asparagine (10.7%) as the main components. Flesh individual FAA, essential amino acid (AA), umami-, and sweet and bitter taste AA strongly depended on foliar nutrients. However, the relation between flesh FAAs and foliar nutrients varied with FAA species. Leaf N was the dominant indicator for most pulp FAAs at two growth stages, while other nutrients (e.g., B, Zn, P, K, Ca, Mg) also played versatile roles on flesh FAAs. This work provides a novel tool to predict fruit FAAs via foliar nutrient diagnosis, which supports the practicality of producing specific target fruit or improving fruit quality through regulation of fertilization strategies in fruit production.
L.X. Zhang, W.C. Chang, Y.J. Wei, L. Liu, and Y.P. Wang
Cryopreservation of pollen from two ginseng species —Panax ginseng L. and P. quinquefolium L.—was studied. Freezing anthers that served as pollen carriers to –40C before liquid N storage affected pollen viability little after liquid N storage. Anther moisture content affected pollen viability significantly when stored in liquid N. The ideal anther moisture content to carry pollen for liquid N storage was 32% to 26% for P. ginseng and 27% to 17% for P. quinquefolium. Viability of pollen from P. quinquefolium anthers with 25.3% moisture content changed little after 11 months of liquid N storage.
Ya-Long Qin, Xiao-Chun Shu, Wei-Bing Zhuang, Feng Peng, and Zhong Wang
Callus induction and plant regeneration play a key role in transgenic technology. Although much progress has been made with respect to eggplant, this type of research is insufficiently developed in Solanum torvum (a wild relative of eggplant), which contains a large number of resistance genes. Here, a high-efficiency regeneration system of S. torvum was established. Stem segments and leaves were cultured on Murashige and Skoog (MS) medium supplemented with 0.5–3.0 mg·L−1 6-benzyladenine (6-BA) and 0.1–0.6 mg·L−1 α-naphthaleneacetic acid (NAA). The highest callus induction ratio (100%) was produced on MS + 1.0 mg·L−1 6-BA + 0.5 mg·L−1 NAA. The combination of 0.5 mg·L−1 BA and 1.0 mg·L−1 2,4-dichlorophenoxyacetic acid in MS medium (double microelement) was the best for plant regeneration. Well-developed shoots rooted on half-strength MS medium supplemented with 0.1 mg·L−1 indole-3-acetic acid (IAA). These results will be helpful for functional verification of resistance genes from S. torvum and may be useful to those working in the field of eggplant breeding.