Investigation into uneven ripening problem in muscadine grape for enhancing their enological characteristics

Hemanth Kn. Vasanthaiah, Sheikh M. Basha, Ramesh Katam, Devaiah Kambiranda


Uniformly ripened, superior-quality grape berries are prerequisite to relishing them as table grapes; processing into juice, jam, and jellies; and also fermenting into wine. Muscadines are extensively cultivated in Florida and are native to southeastern United States. Although muscadine berries have a characteristic aroma and sweetness, there is occurrence of asynchronous ripening within the cluster, which prevents harvesting of the whole cluster at once. With this in view, an investigation was initiated to identify the gene/s associated with ripening and their regulation in muscadine (non-uniform ripening) and Florida hybrid bunch (uniform ripening) grape berry during different ripening stages to understand the molecular basis of ripening. Isolation and characterization of the transcripts expressed during different stages of berry ripening using differential display reverse transcription PCR revealed unique expression patterns of certain transcripts in muscadine and Florida hybrid bunch grapes. These transcripts were identifi ed as calcium-dependent protein kinase (CDPKs) and protein phosphatase 2C (PP2C), which are known to regulate berry ripening process. Expression of PP2C was found only in the muscadine berries, which is a negative regulator of abscisic acid (ABA) signaling. ABA is a phytohormone involved in triggering ripening. Suppression of ABA in certain muscadine berries within the cluster may be the possible reason for its uneven ripening. Further analysis will help in developing muscadine grape cultivars with uniform ripening characteristics to increase product quality, growers’ profi ts, and product marketability.

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Proc. Fla. State Hort. Soc.     ISSN 0886-7283