No abstract

Fresh-cut vegetables are known to be susceptible to contamination; and subsequent growth of microorganisms result in quality concerns. Chinese chive leaves are hollow, cylindrical, and are more inclined to accumulate microbes. Currently, there is limited information on the decontamination of Chinese chives. This research focused on the evaluation of sanitation options for fresh-cut Chinese chives; and the information obtained should be applicable and useful in other fresh-cut vegetables.

The gibberellin 20-oxidase gene (GA20) plays an important role in plant growth and development. Differential expression of Zoysiagrass (Zoysia japonica Steud.) gibberellin 20 oxidase gene (ZjGA20) induced by abiotic stresses has not been reported. In this investigation, we first reported the differential expression of ZjGA20 in different Z. japonica tissues including root, young leaf, senescent leaf, blade, sheath, and stolon, as well as differential expression induced by abiotic stresses including low temperature (4 • C), H2O2(8 µM), salt stress (250 mM NaCl), 25% PEG6000, and high temperature (42 • C) by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR). Higher expression of ZjGA20 was observed in young leaf and sheath, compared to root, senescent leaf, blade, and stolon. Among different abiotic stresses, expression of ZjGA20 decreased under low temperature, 25% PEG6000, and high temperature. The highest expression of ZjGA20 was obtained when plants were treated with 8 µM H2O2 for 10 h and with 250 mM NaCl for 5 h. The analysis of the MDA content, POD activity, and permeability of the plasma membrane demonstrated that application of exogenous GA3 recovered tissue damage derived from low temperature treatment. In addition, the expression of ZjGA20 increased under low temperature stress. These results demonstrated that expression of ZjGA20 was regulated by abiotic stresses and the damage derived from abiotic stresses could be rescued by exogenously applied plant growth regulator GA3. Further more, exogenous gibberellin and salicylic acid (SA) alleviated the growth inhibition and death of the seedlings under stresses. The SA content in the seedlings treated with 80 µM GA3 was far greater than the control (with H2O) and plants under stress treatments. These data suggest that exogenous addition of GA3 is able to counteract the inhibitory effects of these adverse environmental conditions in Zoysiagrass growth through modulation of SA biosynthesis. This is the first study of differential expression of gibberellin 20 oxidase gene and growth regulation of GA3 in Zoysiagrass under stresses.

The quality, antioxidant capacities, and organosulfur profile of chives (Allium schoenoprasum L.) treated with 1-methylcyclopropene (1-MCP) during storage were investigated in this study. The 1-MCP treatment (100 μL/L, fumigation 12 h at 20 °C) effectively inhibited tissue respiration and H2O2 production, enhanced the ascorbic acid (ASA) and glutathione (GSH) content, and promoted the activity of antioxidant enzymes (superoxide dismutase SOD, Catalase CAT, and ascorbic peroxidase APX) during the 5-day storage period at 20 °C. The result further showed that the 1-MCP treatment inhibited chlorophyll degradation, alleviated cell membrane damage, and delayed the chive senescence, with the yellowing rate being reduced by 67.8% and 34.5% in the 1-MCP treated chives on days 4 and 5 of storage at 20 °C, respectively. The free amino acid content of the chive was not affected by the 1-MCP treatment at 20 °C. However, the senescence rate of the chive was not reduced by the 1-MCP treatment when stored at 3 °C. The liquid chromatography data further showed that the 1-MCP treatment induced a 15.3% and 13.9% increase in the isoalliin and total S-alk(en)ylcysteine sulfoxides (ACSOs) content of the chive on day 2 at 20 °C, respectively. Furthermore, there was a strong positive correlation between ACSOs content and CAT/APX activity, indicating that ACSOs probably played a key role in enhancing the antioxidant capacities of the chive during storage at 20 °C. Thus the study efficiently demonstrates that 1-methylcyclopropene preserves the quality of chive (Allium schoenoprasum L.) by enhancing its antioxidant capacities and organosulfur profile during storage.