Cloning and expression analysis of a CCoAOMT homolog in loquat fruit in response to low-temperature storage

• Fruit of two loquat cultivars were stored at 4 °C.
• The appearance did not change, but the firmness and lignin content increased.
• Caffeoyl-coenzyme A 3-O-methyltransferase gene (CCoAOMT) was isolated.
• EjCCoAOMT expression first increased but decreased at the end of storage.

This study aimed to isolate the caffeoyl-coenzyme A 3-O-methyltransferase gene (CCoAOMT) of loquat (Eriobotrya japonica Lindl.) and to investigate the changes in the expression of this gene in loquat fruits that were stored at low temperature. When stored at 4 °C, the fruits of both tested cultivars (‘Jiefangzhong’ and ‘Zaozhong No. 6’) showed no obvious changes in appearance, while their firmness and lignin content increased gradually. Using the RACE technique, EjCCoAOMT was isolated, and the protein alignment indicated that this protein includes the typical 8 motifs belonging to the CCoAOMT protein family and shows high similarity with the other CCoAOMT-like proteins. Its expression in green loquat fruit was lower than that in mature fruit. Low-temperature storage stimulated its expression at the beginning of the storage process, and then the transcription levels decreased throughout the rest of the storage period. These results suggested that the increases in lignin content and firmness in loquat fruit stored at a low temperature may be caused by the induced increase in EjCCoAOMT expression at the initial storage phase.

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