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  • Author or Editor: Yu Dong x
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This study aimed to evaluate whether preharvest or postharvest application of glycine betaine (GB) has the potential to improve fruit quality [fruit firmness (FF), size, skin color, soluble solids content (SSC), and titratable acidity (TA)] and susceptibility to storage disorders (peduncle browning, pitting, and decay) in ‘Lapins’ or ‘Regina’ sweet cherries, and to determine whether factors such as application frequency or timing impacted the efficacy of GB spraying. Adding 2 or 4 g·L−1 GB to hydro-cooling water (0 °C) as postharvest treatment did not affect fruit size, skin color, SSC, TA, peduncle browning, or pitting development; however, it did result in fruit softening and a low incidence of decay. GB applied preharvest at 2 or 4 g·L−1 once at 1 week before harvest (1WBH) was more effective for retaining FF and less peduncle browning and pitting compared with postharvest treatment. Increasing the preharvest GB application frequency from one time (1WBH or pit hardening) to three times (pit hardening, straw color, and 1WBH) enhanced FF and TA levels and resulted in lower pitting. The reduction in fruit size was observed for ‘Regina’, but not for ‘Lapins’. Changes in the contents of phosphorous (P), potassium (K), and magnesium (Mg) were unaffected by GB at harvest, whereas three GB sprays increased the total nitrogen (N) content. Compared with ‘Lapins’, ‘Regina’ allowed more calcium (Ca) uptake by GB and ultimately had firmer flesh. In conclusion, three preharvest applications of 4 g·L−1 GB showed great potential to improve quality attributes, to reduce the susceptibility to storage disorders, and to increase the Ca content of ‘Regina’ cherries.

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This study was undertaken to establish for the first time an efficient regeneration and transformation system for Cucumis metuliferus line PI292190, which is the source of a well-defined resistant gene, Wmv, that provides resistance against Papaya ringspot virus type P (PRSV-P) and PRSV-W (formerly known as Watermelon mosaic virus 1, WMV-1). Different combinations of growth regulators were evaluated for the regeneration of cotyledon explants. Adventitious buds or shoot primordia were obtained within 3 to 4 weeks on regeneration medium. After shoot development, adventitious buds or shoot primordia were transferred to elongation medium for 3 to 4 weeks and these shoots were subcultured onto rooting medium for another 1 to 2 weeks. Under optimal culture conditions, a total of 7 to 10 weeks was necessary to obtain C. metuliferus plantlets from cotyledons. Furthermore, transgenic plants were successfully obtained using an Agrobacterium tumefaciens-mediated transformation method as shown by polymerase chain reaction analysis and histochemical β-glucuronidase (GUS) assay. A total of nine transgenic plants were developed from 360 cotyledon explants, giving a transformation frequency of 2.5%.

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The DNA binding with one finger (Dof), as an important transcription factor, plays an important role in growth and development, primary and secondary metabolism, stress resistance, and plant hormone signal transduction. However, the identification and analysis of the Dof transcription factor family in Rosa is rarely reported. In this study, 28 Rosa chinensis Dof (RcDof) members were identified, which were located on seven chromosomes. The RcDofs were divided into 12 subfamilies according to evolutionary analysis. Through motif, gene structure, and cis-acting element analyses of the 12 subfamilies, the functions of RcDofs were analyzed and predicted. Furthermore, the Dof members in R. chinensis ‘Old Blush’ and another three species (Arabidopsis thaliana, Oryza sativa, and Zea mays) were systematically analyzed. Twelve subfamilies were found in these four species and the motifs and gene structures of Dof members in each subfamily were similar, which further proves that the RcDofs analysis is accurate. Through an intra- and interspecies collinearity analysis, it was found that the collinearity between A. thaliana and R. chinensis is closer in comparison. Tissue expression analysis of RcDofs was by quantitative reverse-transcription polymerase chain reaction (PCR). Quantitative real-time PCR analysis showed expressions of the RcDofs are tissue specific. The RcDofs had higher expression in leaves, roots, and flowers than other tissues. Taken together, this study provides valuable information for future research on functional exploration of RcDof genes and molecular breeding in Rosa.

Open Access

The NAC transcription factor is a peculiar kind of transcription factor in plants. Transcription factors are involved in the expression of plant genes under different conditions, and they play a crucial role in plant response to various biotic and abiotic stress. We transferred the ClNAC9 gene into Chrysanthemum grandiflora ‘niu9717’ by Agrobacterium tumefaciens–mediated transformation. The results of kanamycin-resistant screening, polymerase chain reaction (PCR) detection, and Northern blot analysis proved that the target gene had been integrated into the genome of the target plants. Wild-type (WT) plants and transgenic plants were treated with different concentrations of NaCl, NaHCO3, and drought stress, and physiological indexes, such as antioxidant system activity (superoxide dismutase, peroxidase, catalase), malondialdehyde accumulation, and leaf relative water content, were measured. We also observed changes in plant morphology. The physiological indexes’ changing range and extreme values suggested that transgenic plants’ resistance to salinity, alkali, and drought stress was significantly higher than WT plants. Transgenic plant growth was less inhibited compared with WT plants, indicating that the ClNAC9 gene increased the resistance of transgenic plants under the stress of salinization, alkalization, and drought.

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Hydroponics has been an increasingly important field of vegetable production. However, a big issue with hydroponics is that certain crops can quickly accumulate high levels of nitrate-N (NO3 ± -N) from the hydroponic system. The objective of this research was to decrease NO3 accumulation and increase the nutritional value and yield of vegetable crops using lettuce and oilseed rape as a model under hydroponic production. In this study, two technologies were applied to leafy vegetable production: 1) using supplementary lighting (blue-violet diode) by manipulating illumination and 2) removing fertilization before harvest for a short term (3 or 5 days), thus providing a practical experiment for improving yield and edible qualities of hydroponic leaf vegetable production. Illumination was applied 4 hours a day (0500–0700 hr and 1700–1900 hr) during good weather, or 12 hours a day during bad weather with insufficient natural light (<2000 lux) during the autumn and winter seasons. Results showed that the lettuce cultivar Ou-Luo and the oilseed rape cultivar Ao-Guan Pakchoi had increased yield (50.0% and 88.3%, respectively), decreased NO3 content (26.3% and 30.8%, respectively), and increased total soluble solids (24.1% and 30.6%, respectively). The 5-day fertilizer-free treatment before harvest resulted in 19.2%, 6.4%, and 16.5% yield increases; and 26.0%, 24.3%, and 47.8% NO3 decreases in oilseed rape cultivar Ao-Guan Pakchoi and lettuce cultivars Da-Su-Sheng and Ou-Luo, respectively.

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An efficient biolistic transformation system of banana combined with a liquid medium selection system was developed during this study. An embryogenic cell suspension (ECS) of Musa acuminata cv. Baxi (AAA) was bombarded with a particle delivery system. After 7 days of restoring culture in liquid M2 medium, embryogenic cells were transferred to a liquid selection M2 medium supplemented with 10 μg/mL hygromycin for resistance screening. The untransformed cell clusters were inhibited or killed, and a small number of transformants proliferated in the liquid selection medium. After the 0th, first, second, and third generation of antibiotic screening, there were 0, 65, 212, and 320, respectively, vitality-resistant buds obtained from a 0.5-mL packed cell volume (PCV) of embryogenic cell suspension. The β-glucuronidase (GUS) staining, polymerase chain reaction (PCR) analysis, and Southern blot hybridization results all demonstrated a 100% positive rate of regenerated resistant seedlings. Interestingly, the number of buds obtained through third-generation screening was almost equal to that obtained from the original ECS in M2 medium without antibiotics. These results suggested that the liquid medium selection system facilitated the proliferation of a positive transgenic ECS, which significantly improved the regeneration rate of transformants. This protocol is suitable for the genetic transformation of all banana genotypes and is highly advantageous to varieties with low callusing potential.

Open Access