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  • Author or Editor: Dong Han x
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Anthers of six apple [Malus ×domestica (L.) Borkh.], three Japanese pear (Pyrus pyrifolia N.) and two European pear (Pyrus communis L.) scion cultivars were cultured. Callus formation occurred from anthers of all cultivars and androgenic embryogenesis was observed from all except P. pyrifolia `Kosui' and P. communis `La France'. Regeneration of adventitious shoots from anther-derived embryos was shown from all apple cultivars and P. pyrifolia `Shinko'. Many of these shoots did not grow or died on half-strength Murashige and Skoog medium (1962) with 4.4 μm BA and 0.5 μm IBA, whereas several shoots of apple `Starking Delicious' grew to plantlets. Chromosome counts of shoot apical cells of four clones derived from embryos of `Starking Delicious' showed that three clones were diploids and one clone comprised diploid and haploid shoots, suggesting that at least one clone originated from a microspore. Chemical names used: 3-indolyl-butyric acid (IBA); N6-benzyladenine (BA).

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To study the effects of soil nitrogen (N) fertilization on tea growth, quality and yield, a controlled experiment with green tea [Camellia sinensis (L.) O. Ktze] was conducted. Five N fertilization treatments in soil were designed: 0, 0.97, 1.94, 3.88, and 5.82 g/kg/pot, which were subsequently recorded as N0, N1, N2, N3, and N4. The changes to young shoot biomass, total N and carbon (C), Soil and Plant Analyzer Development (SPAD) value, photosynthetic parameters, senescent characteristics, endogenous hormones, and the quality of green tea leaves were investigated. The results showed that with the increase in N fertilization level, the young shoot biomass, total N and C, SPAD value, net photosynthetic rate (P N), transpiration rate (T r), stomatal conductance (g S), superoxide dismutase activity, indoleacetic acid, gibberellin, zeatin (ZT), caffeine, and amino acids increased at first and then decreased, the maximums appeared at 3.88 g/kg/pot; whereas the intercellular CO2 concentration (C i), malondialdehvde contents, abscisic acid (ABA), polyphenol contents, and the ratio of polyphenols (PP) to free amino acid decreased at first and then increased, the minimums appeared at 3.88 g/kg/pot. The immediately significant change in all parameters appeared after 1 month of N treatments. The experiment showed that 3.88 g/kg/pot N fertilization level was the best for growth, quality, and yield of tea, which could provide a theoretical basis for short-term N fertilization management in tea tree.

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Dehydration response element binding (DREB)1b is a cold-inducible transcription factor in Arabidopsis thaliana. DREB1b driven by cauliflower mosaic virus 35S promoter was genetically introduced into grape Vitis vinifera L. cv. Centennial Seedless through Agrobacterium-mediated transformation for improving its cold resistance and exploring new genetic breeding approaches to obtain cold-resistant cultivars. In this study, Southern blot analysis showed the DREB1b gene was integrated into the transgenic grapevines with one to two copies. Northern blot analysis showed the presence of DREB1b transcripts in the independent transgenic lines 3, 5, 6, and 7. Further characterization of transgenic grapevines confirmed that both electrolyte leakage conductivity and the freezing point of the transgenic plants were lower than those of wild-type plants. After the cold treatment at –4 °C for 12 h, 26% of transgenic plants wilted among which 95% plants recovered once being placed under the condition of temperature 22 to 25 °C. However, subjected to the same treatment, 98% of nontransgenic plants wilted and only 2% recovered. Our results lead to the conclusion that activity of DREB1b in the transgenic grape could significantly improve its resistance to cold stress.

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The structure and chemical properties of strontium and calcium are similar. To study the interplay between calcium and strontium in plants, different concentrations of SrCl2 (0, 1, 4, and 10 mmol·L−1) were added to the Hoagland nutrient solution with 4 mmol·L−1 Ca2+ (normal level Ca2+) or 0.4 mmol·L−1 Ca2+ (low-level Ca2+), which were used to cultivate Chinese cabbage seedlings. Under the low-level calcium condition, strontium not only did not promote the growth of Chinese cabbage but showed more severe toxicity compared with that under the normal calcium condition. Under normal calcium condition, although the growth of Chinese cabbage was significantly inhibited by 4 mmol·L−1 strontium, strontium did not show significant toxicity. However, under the low-level calcium condition, 1 mmol·L−1 strontium caused a significant decline of plant biomass and photosynthetic activity. Sr2+ showed a competitive inhibitory effect on the absorption of Ca2+, and strontium was more easily absorbed by Chinese cabbage. Under the low-level calcium condition, strontium aggravated the inhibition of calcium absorption. The inhibitory effect of strontium on plant growth was significantly related to the calcium content in Chinese cabbage. Strontium cannot replace the function of calcium in plants under calcium-deficient conditions.

Open Access

The efficiency of volatile formaldehyde removal was assessed in 86 species of plants representing five general classes (ferns, woody foliage plants, herbaceous foliage plants, Korean native plants, and herbs). Phytoremediation potential was assessed by exposing the plants to gaseous formaldehyde (2.0 μL·L−1) in airtight chambers (1.0 m3) constructed of inert materials and measuring the rate of removal. Osmunda japonica, Selaginella tamariscina, Davallia mariesii, Polypodium formosanum, Psidium guajava, Lavandula spp., Pteris dispar, Pteris multifida, and Pelargonium spp. were the most effective species tested, removing more than 1.87 μg·m−3·cm−2 over 5 h. Ferns had the highest formaldehyde removal efficiency of the classes of plants tested with O. japonica the most effective of the 86 species (i.e., 6.64 μg·m−3·cm−2 leaf area over 5 h). The most effective species in individual classes were: ferns—Osmunda japonica, Selaginella tamariscina, and Davallia mariesii; woody foliage plants—Psidium guajava, Rhapis excels, and Zamia pumila; herbaceous foliage plants—Chlorophytum bichetii, Dieffenbachia ‘Marianne’, Tillandsia cyanea, and Anthurium andraeanum; Korean native plants—Nandina domestica; and herbs—Lavandula spp., Pelargonium spp., and Rosmarinus officinalis. The species were separated into three general groups based on their formaldehyde removal efficiency: excellent (greater than 1.2 μg·m−3 formaldehyde per cm2 of leaf area over 5 h), intermediate (1.2 or less to 0.6), and poor (less than 0.6). Species classified as excellent are considered viable phytoremediation candidates for homes and offices where volatile formaldehyde is a concern.

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