Avocado Fruit Pulp Transcriptomes in the after-Ripening Process

Abstract

Avocado is an important tropical fruit whose after-ripening process is still poorly understood. The fatty acid, phenolics, flavonoids, and tannins were analyzed in ‘Lisa’ avocado (Persea americana Mill. ‘Lisa’) fruit pulp during after-ripening. The transcriptome was analyzed to screen for transcripts associated with the aforementioned after-ripening parameters. The results showed that there were no significant differences in the total fatty acid content among the preclimacteric, climacteric, and postclimacteric stages. Nevertheless, the concentrations of C18:3 (α-linolenic acid) were significantly higher in the climacteric and postclimacteric stages than the preclimacteric stage. RNAseq generated 235,082 transcripts and 151,545 unigenes. In addition, 4,324 DEGs were produced among the three stages. KEGG analysis of the DEGs suggested the pathways about “α-linolenic acid metabolism, unsaturated fatty acid biosynthesis”, “fatty acid degradation”, “linoleic acid metabolism and fatty acid biosynthesis”, “linoleic acid metabolism and fatty acid elongation”, and “fatty acid elongation” may all contribute to the C18:3 variations in ‘Lisa’ avocado fruit pulp. Several transcription factors, including the ethylene-related transcription factors, such as NAC, MYB, bHLH, and WRKY, were also identified in the DEGs database. This study generated transcript data and screened the transcription factors involved in the avocado after-ripening process. This information could be used to control after-ripening in avocado and maintain fruit quality during storage.