1-Methylcyclopropene affects ethylene synthesis and chlorophyll degradation during cold storage of ‘Comice’ pears
Jing Zhao, Xingbin Xie, Shuaishuai Wang, Honglu Zhu, Wanwan Dun, Linzhong Zhang, Yan Wang and Congbing Fang
Scientia Horticulturae 260: 108865. (2020)
2020
บทคัดย่อ
Loss of green skin color and the onset of senescent scald (scald) in ‘Comice’ pears affect fruit quality and reduce the market value. To understand the molecular mechanisms of chlorophyll degradation in the skins of ‘Comice’ pears, fruit were exposed to 1-methylcyclopropene (1-MCP) at 0.15 and 0.3 µL L−1 and stored at -1.1 °C for up to six months. The results showed ethylene production rate, and respiration rate were significantly inhibited in pears treated with 1-MCP at 0.15 and 0.3 µL L−1. Senescent scald was eliminated, and the amount of extractable juice (EJ) remained constant, and chlorophyll degradation was retarded. However, the ripening capacity was inhibited. Ripening capacity recovered (by 14 days following warming to room temperature) in pears treated with 1-MCP at the lower concentration (0.15 µ L L−1) but the fruit treated with 1-MCP at the higher concentration (0.3 µL L−1) failed to ripen. The expressions of the ethylene synthesis genes (PcACS1, PcACS4, PcACS5, and PcACO1) and receptor genes (PcETR1, PcETR2, PcETR5, and PcERS1) were upregulated during storage in the control fruit but were significantly repressed by the 1-MCP treatments. In contrast, the expression of PcACS2 was upregulated by the 1-MCP treatments. The expressions of the chlorophyll degradation genes (PcPPH, PcNOL, PcSGR1, and PcPAO) were significantly higher in the control fruit but suppressed in the 1-MCP-treated fruit. The transcription levels of PcRCCR and PcCLH1 decreased during the six months of cold storage period and 1-MCP had little effect on their expressions. The correlations between chlorophyll degradation and the ethylene synthesis genes and signal-related genes indicated that 1-MCP delayed chlorophyll degradation by inhibiting the ethylene production rate and suppressing the expressions of the PcPPH, PcNOL, PcSGR1, and PcPAO genes, which were closely associated with the chlorophyll catabolic pathway in ‘Comice’ pears.