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Hydroponic systems in plant factories can be categorized into recirculating or noncirculating systems. In this study, the effects of various commercially available circulation pumps, including a centrifugal magnetic drive pump, a regenerative self-priming pump, and a submersible pump, were experimentally explored. In addition, the effects of an ultraviolet sterilization system on the ion concentrations in nutrient solutions were examined. The concentrations of sodium, potassium, magnesium, calcium, nitrate, sulfate, and ferric (Fe3+) ions in the nutrient solution were measured. For all three types of pumps, the results indicated that there was no significant effect on the concentrations of ions in the nutrient solution. However, the concentration of Fe3+ ions decreased significantly after the nutrient solution was treated by a ultraviolet sterilization system for 48 hours. In addition, the effects of the three types of pumps on the growth of butterhead lettuce (Lactuca sativa) were examined. The temperature records during the pump circulation tests showed that the nutrient solution temperature of the regenerative self-priming pump increased by 15.5 °C (from 20.5 to 36 °C), which caused yellow seedling, scorching on the leaves, and browning of the roots. The ion concentration in the nutrient solutions and total fresh weight of butterhead lettuce did not show any noticeable difference between the centrifugal magnetic drive pump and the submersible pump. In this paper, we clarify the cause of the decreasing iron concentration and provide a guideline for selecting the pump for circulating hydroponic systems in plant factories.
The MADS-box gene family encodes a type of transcription factor, and plays a key role in the growth and development of plants. Here, we identified 62 MADS-box genes in the melon (Cucumis melo) genome using bioinformatics methods. These genes were divided into type I Mα, Mγ, and Mδ subfamilies (26 members) and type II MIKCC subfamilies (36 members) by phylogenetic analysis. There were no genes in type II AGL12, BS, TM8, and MIKC* subfamilies, and type I Mβ subfamilies. Conserved motif analysis showed that all motifs had a subfamily-specific distribution except the M domain. The expression analysis of the MADS-box genes showed different expression characteristics. In summary, this study is the first to identify melon MADS-box genes and analyze their gene structures, subfamily distribution, and expression characteristics. These results provide a foundation for investigating the functions of the melon MADS-box genes.
In the early Spring of 2015 and 2016, weed infestation surveys were conducted in areas of cool-season turfgrass Festuca arundinacea Schreb. at 23 sites within Tianjin municipality in northern China. The weed community within turfgrass areas comprised 37 weed species belonging to 14 families. Perennial weeds accounted for 45.9% of the total community of weed species, whereas annual or biennial weeds accounted for 54.1%. Asteraceae was the dominant family (43.2%), and the percentage of broadleaved weeds was 94.6%. Statistical analyses of the weed dominance index (integrating weed relative height and relative coverage) and relative abundance (integrating weed relative density, frequency, and uniformity) showed that the 10 most common weed species during the early spring were Ixeris polycephala Cass., Taraxacum mongolicum Hand.-Mazz., Inula japonica Thunb., Hemistepta lyrata Bge., Trigonotis pedunclaris (Trev.) Benth., Calystegia hederacea Wall., Lepidium apetalum Willd., Plantago asiatica L., Cirsium segetum Bge., and Ixeris sonchifolia Hance. Ixeris polycephala Cass. and T. mongolicum Hand.-Mazz were the most dominant and harmful weed species. Partial correlation analysis (PACA) indicated that the deterioration rate (percentage of bare soil or coverage of plants other than turfgrass) of the turfgrass area was significantly and positively correlated with the total dominance index [(TDI), an index to evaluate the weed infestation severity)] and that the soil organic matter (SOM) and salinity factors were negatively correlated with the TDI. Factors such as soil nutrient conditions (the contents of N, P, and K and the total N), soil physical properties (density and clay content), soil moisture, soil temperature, and soil pH did not correlate significantly with the TDI. We conclude that the deterioration rate was the most important factor influencing weed infestation in the early spring and that SOM and soil salinity might also be important factors. The results of this study can help turfgrass researchers and managers identify the most harmful weed species and integrate management strategies in areas of cool-season turfgrass F. arundinacea Schreb. during early spring in the Tianjin region, China.
Amorphophallus species are one of the main economic crops in the mountainous areas of southwest China. However, soft rot disease (Pectobacterium carotovorum ssp. carotovorum) is devastating for this crop. This study explored the Amorphophallus resistance mechanism against soft rot disease by analyzing transcriptome data using a weighted gene coexpression network analysis. The RNA sequencing of plants infected for 0, 12, 24, and 48 hours produced a total of 52.25 Gb of clean reads. A total of 29,096 genes were divided into 34 modules. Six modules of interest with the highest correlation with the target traits were selected to elucidate the resistance genes and pathways. The selected modules were enriched in the α-linolenic acid metabolism, phenylpropane biosynthesis, plant hormone signal transduction, and plant pathogen interaction pathways. Ultimately, AmBGLU, AmCAML, AmCDPK, AmLOX, and AmRBOHD were identified as genes of interest in the four significantly related metabolic pathways for real-time fluorescence quantitative polymerase chain reaction verification. The determination of salicylic acid (SA) and jasmonic acid (JA) in Amorphophallus muelleri and Amorphophallus konjac that suffered from soft rot disease showed that SA and JA were involved in the A. muelleri and A. konjac defense response against soft rot disease. Methyl jasmonate treatment delayed the onset of A. konjac soft rot disease. This study provides a reference for the interaction between Amorphophallus species and soft rot disease and the breeding of broad-spectrum and specific Amorphophallus cultivars that are resistant to soft rot disease.
The banana, a typical climacteric fruit, undergoes a postharvest ripening process followed by a burst in ethylene production that signals the beginning of the climacteric period. Postharvest ripening plays an important role in improving the quality of the fruit as well as limiting its shelf life. To investigate the role of glutamate decarboxylase (GAD) in climacteric ethylene biosynthesis and fruit ripening in postharvest banana, a GAD gene was isolated from banana, designated MuGAD. Coincidently with climacteric ethylene production, MuGAD expression as well as the expression of the genes encoding the Musa 1-aminocyclopropane-1-carboxylate synthase (MaACS1) and Musa 1-aminocyclopropane-1-carboxylate oxidase (MaACO1) greatly increased during natural ripening and in ethylene-treated banana. Moreover, ethylene biosynthesis, ripening progress, and MuGAD, MaACS1, and MaACO1 expression were enhanced by exogenous ethylene application and inhibited by 1-methylcyclopropene (1-MCP). Taken together, our results suggested that MuGAD is involved in the fruit ripening process in postharvest banana.
The chloroplast genome of an albino mutant isolated from tissue culture of the bamboo Bambusa edulis Munro was examined to identify aberrations. A number of the chloroplast genes encoding ATP synthases, photosystem II subunits, NADH dehydrogenase, and ribosomal proteins had been deleted, at least partially, in the albino mutant. Comparison of the two-dimensional electrophoresis profiles of albino and green bamboos revealed three spots of reduced intensity, indicating repression of these proteins in the albino mutants. Mass spectroscopic analysis subsequently revealed that two of these proteins are 33-kDa subunits of the photosystem II oxygen-evolving protein complex (PsbO) and one is a 23-kDa subunit of photosystem II oxygen-evolving protein complex (PsbP). The genes encoding these two proteins were cloned from B. edulis, and were denoted BePsbO (accession no. EF669513) and BePsbP (accession no. EF669512). Reverse transcription polymerase chain reaction and two-dimensional gel analyses of BePsbO and BePsbP in green and albino bamboos grown in the light or dark revealed that the albino mutant, similar to its green counterpart, sensed the light signal, resulting in the induction of BePsbO and BePsbP transcription, but it did not accumulate the protein products. We conclude that the repression of protein-expressing BePsbO and BePsbP is because of a defect in post-transcriptional regulation in the albino mutant.