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  • Author or Editor: Chen Wang x
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Watermelon (Citrullus lanatus) is an economically important cucurbit (Cucurbitaceae) crop cultivated globally for its nutritional benefits. Fruit development in watermelon is characterized by fast fruit expansion attributed to unique biological processes. Myeloblastosis (MYB) family genes play important roles in plant growth and development, especially R2R3-MYB-type genes. However, the evolution of R2R3-MYB family genes in the watermelon genome and whether they participate in the regulation of watermelon fruit development remain unknown. To address these questions, duplication modes of R2R3-MYB family genes were identified and their expression profiles were investigated during watermelon fruit development. A total of 48 duplicated gene pairs were identified among the 89 R2R3-MYBs in watermelon. Segmental and transposed duplication events play major roles in the R2R3-MYB family gene expansion process. The ratio of nonsynonymous mutation and synonymous mutation analysis indicated that all the duplicated R2R3-MYBs experienced negative selection. Gene structures and cis-element compositions in promoter sequences exhibited abundant divergences between the R2R3-MYB duplicated genes. Transcriptome analyses of seed, rind, and flesh during fruit development showed that only two duplicated gene pairs had significantly similar expression patterns, whereas divergent expression profiles were found between the remaining duplicated gene pairs. Tissue-specific and development stage-specific divergent expression patterns demonstrated that neo-functionalization occurred between watermelon R2R3-MYB duplicated genes. The current study provides valuable information for further functional analyses of R2R3-MYBs in watermelon.

Open Access

Overapplication of nutrients and water is common in intensive greenhouse systems. A 2-year experiment (2011–13) was conducted to study the effect of different nutrient and water treatments on the growth and yield of tomato (Lycopersicum esculentum Mill.) and on soil nutrient accumulations in solar greenhouses in South Loess Plateau, China. The treatments included 1) current fertilizer and water practices (FW), 2) formula fertilizer and water 1 (FW1), 3) formula fertilizer and water 2 (FW2), and 4) farmer’s practice (FP). Compared with FW, FW1 and FW2 had yields not significantly different from grower control treatments; however, they saved 35% to 46% of the nitrogen (N) fertilizer, 40% to 54% of the phosphorus (P2O5) fertilizer, 19% to 35% of the potassium (K2O) fertilizer, and 15% to 21% of irrigation water. The economic profits of FW1 and FW2 were greater than those of the FW and FP treatments. The two formula treatments also reduced soil electrical conductivity (EC) and the accumulation of nitrate, available P, and available K in soil. However, the soil nutrients are still above optimal levels. Obvious N surplus in the greenhouse was observed in different treatments, mainly because of high N input from manures. This study revealed there is great potential to reduce nutrient and water use while maintaining the same yield in a greenhouse system.

Free access

In China, greenhouse soils often receive large rates of different manures and have a high content of soil organic matter (SOM). Understanding changes in nitrogen (N) mineralization in soils of newly built greenhouses after their construction is important for managing N. Soil samples were obtained from solar greenhouses of different ages (0, 1, 2, and 3 years) located in the south edge of the Loess Plateau, China, at 0- to 20- and 20- to 40-cm depth. N mineralization in the soils was measured with the Stanford and Smith long-term aerobic incubation method over 30 weeks. SOM, total N, and the mineralized N in the 0- to 20-cm and 20- to 40-cm soil layers were significantly increased in the older greenhouses. The cumulative mineralized N in the 0- to 20-cm soil layer in different cultivation years was increased in each year since the greenhouses were established. For the greenhouses with the same age, the cumulative mineralized N in the 0- to 20-cm soil layer was greater than that in the 20- to 40-cm layer. The potentially mineralizable N (N0) both in the 0- to 20-cm and the 20- to 40-cm soil layers increased with the greenhouses’ age. Regression analysis indicated that when SOM increased 1 g·kg−1, N0 in the 0- to 20-cm and 20- to 40-cm depth increased 22.6 and 8.4 mg·kg−1, respectively. Therefore, as the N supply in soil increases with the age of the solar greenhouse, we suggest that the application rates of manure and synthetic fertilizer be reduced.

Free access

Volatile chemicals emitted from the flowers of globe amaranth (Gomphrena globosa) were collected using a dynamic headspace technique and analyzed using gas chromatography–mass spectrometry. Among the four globe amaranth cultivars analyzed, Fireworks was the highest producer of floral volatiles. The flowers of the other three cultivars, Las Vegas White, Las Vegas Pink, and Las Vegas Purple, emit less volatiles, both qualitatively and quantitatively, than ‘Fireworks’. ‘Fireworks’ was chosen for detailed characterization of regulation of floral volatile emission. A diurnal pattern of emission of floral volatiles was observed from the flowers of ‘Fireworks’. In addition, the emission pattern was not significantly affected by light, suggesting that the circadian clock plays a major role in the regulation of volatile emission. The emission of floral volatiles from ‘Fireworks’ flowers that were treated with several chemicals was also analyzed. The treatment with silver thiosulphate, an ethylene inhibitor, led to enhanced emission of total volatiles. In contrast, the treatments with salicylic acid and jasmonic acid led to enhanced emission of total floral volatiles at 4 h but reduced emission at 24 h after the treatment. Biochemical pathways leading to the production of the major floral volatiles of globe amaranth are proposed and partly validated by cluster analysis of floral volatiles emitted from ‘Fireworks’ flowers under various conditions. The implications of the results of this study to the understanding of the reproductive biology of globe amaranth and the breeding of novel globe amaranth cultivars are discussed.

Free access

The objective of this study was to investigate ascorbic acid (AsA) accumulation, mRNA expression of genes involved in AsA biosynthesis as well as recycling, activity of key enzymes, and the relationship of them to AsA levels during the development of apple fruit (Malus ×domestica cv. Gala). AsA concentration, which mainly depends on biosynthesis, was the highest in young fruit post-anthesis and then decreased steadily toward maturation. However, AsA continued to accumulate over time because of the increase in fruit mass. Transcript levels of guanosine diphosphate (GDP)-L-galactose phosphorylase, GDP-mannose pyrophosphorylase, D-galacturonate reductase, and the post-transcriptionally regulated L-galactono-1,4-lactone dehydrogenase were not correlated with AsA accumulation in apple. In contrast, patterns of expression for L-galactose dehydrogenase, L-galactose-1-phosphate phosphatase, and GDP-mannose-3′,5′-epimerase showed a pattern of change similar to that of AsA accumulation. Although activities and expression levels of monodehydroascorbate reductase and dehydroascorbate reductase in fruit, which had less capacity for AsA recycling, were much lower than in leaves, they were not clearly correlated with AsA level during fruit development.

Free access

Grafting is widely used in the commercial production of cucurbits (Cucurbitaceae) and solanaceous (Solanaceae) vegetables, but seldom in the production of cruciferous vegetables such as cabbage (Brassica oleracea Capitata group). In our study, we developed a tube grafting method for cabbage using the ‘K-Y cross’ cabbage as the scion and ‘Tsuei Jin’ chinese kale (B. oleracea Alboglabra group) as the rootstock (K-Y/TJ), and then used the K-Y/TJ grafted seedlings to identify the best healing conditions. The examined healing conditions included temperature (15, 20, or 25 °C), relative humidity (RH; 75%, 85%, or 95%), and light intensity (high light intensity, 79 to 107 μmol·m–2·s–1; low light intensity, 38.6 to 58.8 μmol·m–2·s–1; or full darkness, 0 μmol·m–2·s–1). Considering all the healing conditions, the K-Y/TJ grafted seedlings healing at 20 °C, 95% RH, and high light intensity exhibited survival rates of up to 96.7% and overall superior seedling quality. ‘K-Y cross’ cabbages were then grafted onto chinese kale rootstocks, and the head traits of all grafted plants were comparable to those of nongrafted and/or self-grafted ‘K-Y cross’ plants. ‘K-Y cross’ plants grafted on ‘Jie Lan’ chinese kale rootstocks had greater ascorbic acid and total soluble solid (TSS) contents than nongrafted and self-grafted ‘K-Y cross’ plants. Overall, this research describes a successful tube grafting method and the optimal healing conditions for grafted cabbage seedlings, which can be used as a tool to improve head quality.

Open Access

Shennongjia mountain region is famous for its various kinds of species. Through one year's deep-going expedition in the area, lots of valuable plant species were collected, among them many are very useful and had not been used in landscape. Such as Arisaema lobatum var. variegatum nv. LuDiFei, Cremastra appendiculata var. fulva LuDiFei, Stylophorum lasiocarpum (Oliv.) Fedde, Sedum filipes Hems., Iris wilsonii C. H. Wright, Amaranthus caudatus L., Cotoneaster dammeri Schneid, Meconopsis quintupineria Regel., Lysimachia paridiformis Franch., Dysoma versipellis (Hance) M. Cheng, Adiantum pedatum L. and so on. Some genera are quite rich in this region, especially in Rosa, Sorbus, Cotoneaster, Lonicera, Impatiens, Aconitum, Gentiana, Adiantum etc. All these are marvelous material for direct appliance in garden and for breeding. There are many rare plants in the area, large communities of Davidia involucrata Baillon and Chimonanthus praecox (L.) Link were found during the expedition, and what interesting more is that various natural variations do exist in the communities. Detail description and evaluation were given to the important species, and some suggestions of protection and utilization were offered in the paper.

Free access

Breeding for dwarf-type bermudagrass (Cynodon dactylon) with enhanced drought resistance is important for producing quality turf with reduced irrigation. A dwarf-type mutant (S-20–1) that exhibits slower vertical growth, and shorter internodes and leaf length was selected from the gamma-ray–irradiated seeds of a bermudagrass cultivar Sundevil II (S-CK). S-20–1 had slower turf coverage than S-CK. Compared with S-CK, the vertical growth of S-20–1 was more promoted by gibberellin (GA3) treatment. S-20–1 showed an enhanced drought resistance in greenhouse and field tests. Under drought stress, S-20–1 maintained higher relative water content and lower levels of ion leakage, malondialdehyde, and leaf firing than S-CK. Antioxidant enzyme activities and antioxidant content showed no difference between S-20–1 and S-CK under well-watered conditions, while higher enzyme activities were maintained in S-20–1 under drought stress. Free proline accumulated in response to drought stress and showed a positive correlation to the increased ion leakage, while S-20–1 had lower levels than S-CK. Our results indicated that the dwarfism in S-20–1 induced by gamma-ray irradiation might be the result of less GA3 or decrease of sensitivity to GA3 in the mutant. The improved drought resistance of the mutant is associated with maintenance of higher levels of antioxidant enzyme activities. More accumulation of proline in S-CK than S-20–1 reflected a physiological response to the drought-induced injury rather than an association with drought resistance of S-20–1.

Free access