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- Author or Editor: Jun Yu x
Spine grape (Vitis davidii Foex) is an important wild plant species in South China. To provide economical and environmentally safe ways to promote the precocious maturation of spine grape berries, the effects of riboflavin were investigated. Riboflavin affected the reactive oxygen species metabolism in spine grape berries by increasing superoxide radical production and the hydrogen peroxide content, and it impaired the activities of the antioxidant enzymes superoxide dismutase and catalase. Riboflavin also induced the upregulated expression of maturation-related genes in advance, and the earlier accumulation of anthocyanin and total soluble solids. Phenological observations revealed that the treated grape berries underwent a color-turning stage 9 days earlier than the control, and the maturation stage occurred 7 days earlier than the control. Thus, riboflavin may significantly promote the precocious maturation of spine grape berries.
Grapefruit seeds were studied for the extraction of limonoids using supercritical CO2 extraction (SC-CO2) technique. Limonin aglycone was successfully extracted with SC-CO2 directly from grapefruit seeds; and the limonin glycoside was extracted using SC-CO2 and ethanol as co-solvent from the spent seeds after the extraction of limonin aglycone. In an effort to optimize the extraction conditions of limonin aglycone, pressure, temperature, time effects were investigated. Various times of extraction, CO2 flow rate and the feeding modes of CO2 were also employed to obtain the highest yield of limonin aglycone. Optimal conditions to achieve the highest limonin aglycone (0.63 mg/g seeds) were 48.3 MPa, 50°C and 60 min with CO2 bottom feeding, flow rate about 5 L/min. The extraction conditions for limonin glycoside to achieve highest yield were further optimized. The highest extraction yield (0.62 mg limonin glycoside/g seeds) were at 48.3 MPa, 50°C, 30% molar fraction of ethanol (XEth =0.30) and 40 min with CO2 top feeding, flow rate about 5 L/min. The results demonstrated that supercritical CO2 extraction of limonoids from grapefruit seeds, a citrus juice industry byproduct, has practical significance for commercial production.
Light, as the energy and signal sources for plant growth and development, is one of the most important environment factors in recently developed plant factories with artificial light (PFALs). To find the optimal combination of light wavelengths for lettuce (Lactuca sativa cv. ‘Tiberius’) plant growth in a PFAL, four treatments, each using red (R; 662 nm) and blue light (B; 447 nm) with a ratio of 4:1 and photon flux density (PFD) of 150 μmol·m−2·s−1, and mixing, respectively, with 50 μmol·m−2·s−1 of green light (G; 525 nm; RBG), yellow light (Y; 592 nm; RBY), orange light (O; 605 nm; RBO) and far-red light (FR; 742 nm; RBFR), were set up during this experiment. A combination of R and B with a ratio of 4:1 and PFD of 200 μmol·m−2·s−1 was set as the control (RB). The responses of lettuce growth, morphology, anatomical structure of the lettuce leaf, photosynthetic performance, lettuce nutritional quality, and energy use efficiency were investigated. The results showed that RBG, RBO, and RBFR increased the shoot fresh weight of lettuce by 20.5%, 19.6%, and 40.4%, and they increased the shoot dry weight of lettuce by 24.2%, 13.4%, and 45.2%, respectively, compared with those under RB. The Pn under RBY was significantly lower than that under RB, although no significant differences in chlorophyll or carotenoid content were found between RBY and RB. RBG increased the lettuce leaf area, the thickness of the leaf palisade tissue, Pn, and light use efficiency compared with those under RB. Plants grown under RBO showed better photosynthetic capacity, such as higher Pn, ΦPSII, and other photosynthetic parameters. RBFR caused an increase in lettuce leaf area and energy use efficiency, but a decrease in leaf thickness and Pn of the single leaf. Moreover, tipburn injury was observed under RBFR. Therefore, these results demonstrate that RBG and RBO can be considered optimal combinations of light wavelengths for lettuce growth in a PFAL in this experiment, although plant growth can also be improved by using RBFR.
Plant growth and development are determined by complex exogenous and endogenous cues. A plant follows several temporally distinct developmental stages, including embryonic, vegetative, and reproductive. The vegetative stage, which is usually the longest stage, can be subdivided into juvenile and adult phases. The transition from the juvenile to the adult phase, also called the vegetative phase change, is characterized by anatomical, morphological, and physiological changes in the vegetative parts of the shoot. Recent studies in several systems have identified the genetic temporal mechanisms of this process, which is regulated by an endogenous age cue (i.e., microRNA156/157) and its targeted genes (i.e., Squamosa promoter binding protein-box transcription factors). This review summarizes the recent advances in the study of the underlying regulatory mechanisms of vegetative phase change. This review also describes the modes of miRNA action and the functions of their targeted genes in this highly conserved developmental process.
Grafted transplants are widely used for watermelon culture in Korea mainly to reduce the yield and quality losses caused by soil-borne diseases. It is normal practice to cure the grafted transplants under high relative humidity (RH) and low photosynthetic photon flux (PPF) conditions for a few days after grafting to prevent the wilting of the transplants. Transpiration rate (TR) and net photosynthetic rate (NPR), however, could be suppressed under those environmental conditions. In the present study, TR and NPR of the grafted watermelon transplants were compared during graft union formation under 18 environmental conditions combining two air temperatures (20 and 28 °C), three RHs (60%, 80%, and 100%), and three PPF s (0, 100, and 200 μmol·m-2·s-1). Percentages of graft union formation and survival were also evaluated. TR and NPR dramatically decreased just after grafting but slowly recovered 2 to 3 days after grafting at 28 °C. The recovery was clearer at higher PPF and lower RH. On the other hand, the recovery of TR and NPR was not observed in 7 days after grafting at 20 °C. Differences in TR and NPR affected by RH were nonsignificant. Percentage of graft union formation was 98% when air temperature, RH, and PPF were 28 °C, 100%, and 100 μmol·m-2·s-1, respectively, which was the highest among all the treatments. Percentage of survival was over 90% when air temperature was 28 °C and RH was higher than 80% (when vapor pressure deficit was lower than 0.76 kPa). In addition, higher PPF enhanced TR and NPR and promoted rooting and subsequent growth of grafted transplants. Results suggest that the acclimation process for grafted watermelon transplants can be omitted by properly manipulating environmental factors during graft union formation.
Pedicularis rex C. B. Clarke ex Maxim., an endemic species with potential horticultural traits from Himalaya, has a unique cup-like petiole structure and highly infraspecific floral variation among members of the lousewort genus (Orobanchaceae). We developed 13 microsatellite markers from three microsatellite-enriched libraries (AG, AC, and AAG) of P. rex with a modified biotin–streptavidin capture technique. Polymorphism of each locus was assessed in 22 individuals with representation of five populations of P. rex. Number of alleles per locus (A) ranged from two to seven with an average of 4.38. The observed and expected heterozygosities varied from 0.03 to 0.86 and 0.45 to 0.84, respectively. Additionally, among the 13 identified microsatellite markers, 11 of them were successfully amplified in species P. thamnophila, and five of them showed polymorphisms. This study may provide important information for further investigation on the population genetics, introduction, and acclimatization of P. rex and its congeners.
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.
The autotoxicity of root exudates and the change of rhizosphere soil microbes are two important factors that affect the quality and yield of Lanzhou lily (Lilium davidii var. unicolor). Phthalic acid (PA) is a major autotoxin of the root exudates in Lanzhou lily. In this study, we treated plants with different concentrations of PA from the Lanzhou lily root exudates and then analyzed the effects of autotoxins on fresh weight, shoot height, root length, and Oxygen Radical Absorbance Capacity in root. The diversity of soil fungi in Lanzhou lily soil was analyzed using MiSeq. The results showed that PA induced oxidative stress and oxidative damage of Lanzhou lily roots, improved the level of the membrane lipid peroxidation, reduced the content of antioxidant defense enzyme activity and the nonenzymatic antioxidant, and eventually inhibited the growth of the Lanzhou lily. We found that continuous cropping of Lanzhou lily resulted in an increase in fungal pathogens, such as Fusarium oxysporum in the soil, and reduced the size of plant-beneficial bacteria populations. The results in this study indicate that continuous cropping would damage the regular growth of Lanzhou lily.
This study explored the effects of different colored bags (blue, green, white, yellow, orange, and red) on russet deposition on the peel of semi-russet ‘Cuiguan’ pears 10 days after full bloom (DAFB). The process of russeting of the peel and structure of the cork layer were characterized by microscopy and scanning electron microscopy (SEM), followed by the detection of lignin and the activity of enzymes involved in lignin synthesis. The expression of cinnamate-4-hydroxylase, 4-coumarate:coenzyme A ligase, cinnamyl alcohol dehydrogenase, cinnamoyl-CoA reductase, and peroxidase, which were related to phenylalanine ammonia-lyase, was determined via real-time quantitative polymerase chain reaction. Russeting of the outer peel of ‘Cuiguan’ pear accumulated rapidly at 80 DAFB, and a positive relationship between the russet index and lignin content was observed. Red and infrared (IR) ray, partial far-IR light (600–800 nm), and ultraviolet-A light (350–400 nm) promoted russeting in ‘Cuiguan’ pear peel, whereas green light decreased russeting, the russet index, enzymatic activities, and the expression levels of enzymes involved in lignin synthesis. Values of all these factors were higher for ‘Cuiguan’ pears in red bags than for those in bags of other colors. These findings suggested that spectral components affected the synthesis of lignin and the formation of fruit russet. Storage in green bags reduced russeting and improved fruit appearance.