Developmental Profiles Of The Avocado Fruit Transcriptome During Oil Accumulation

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Unlike most other fruits that accumulate oil in seed tissues, avocado stores large amounts of oil in the form of triacylglycerol (TAG) in its mesocarp tissue. The regulation of TAG biosynthetic pathways in such nonseed tissues is poorly understood. RNA-Seq was used to identify the transcriptional networks underlying TAG biosynthesis in developing mesocarp of avocado. Deep transcriptional profiling studies revealed that several transcripts were differentially represented between the early and late developmental stages of mesocarp. The temporal expression pattern of transcripts associated with fatty acid biosynthesis in plastid coincided with increasing oil content. Furthermore, except for the transcripts that likely encode enzymes involved in the terminal step in TAG synthesis, others involved in TAG assembly in the endoplasmic reticulum were poorly expressed. This pattern of higher expression for genes involved in fatty acid synthesis but not TAG assembly was similar to previously observed pattern in other seed and nonseed tissues. Comparative analysis of transcript levels for about 1500 transcription factors, across different species and oil-storing tissues, also revealed that WRINKLED1 may be highly conserved across species but transcriptional regulation of oil biosynthesis, includes distinct tissue-specific features. In conclusion, while the biochemical pathways for oil biosynthesis in nonseed tissue are highly similar to that of seed tissues, certain distinctive modes of regulation of fatty acid biosynthesis and TAG assembly likely occur in oil-rich nonseed tissues.


San Diego, CA

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