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ARS Home » Pacific West Area » Wenatchee, Washington » Physiology and Pathology of Tree Fruits Research » Research » Publications at this Location » Publication #232799

Title: Identification of differentially expressed genes potentially associated with apple (Malus x domestica) superficial scald development

Author
item Zhu, Yanmin
item Varanasi, Vijaya
item Zheng, Ping
item Curry, Eric
item Mattheis, James

Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/22/2011
Publication Date: 4/8/2012
Citation: Zhu, Y., Varanasi, V., Zheng, P., Curry, E.A., Mattheis, J.P. 2012. Identification of differentially expressed genes potentially associated with apple (Malus x domestica) superficial scald development. Acta Horticulturae. doi: 10.17660/ActaHortic.2012.945.60.

Interpretive Summary: Apple superficial scald (scald) is a recurring postharvest physiological disorder with significant economic impact. Although it has long been hypothesized that oxidative imbalance due to the cold stress during storage is the potential cause, yet there is limited evidences, particularly at molecular level. Elucidating the molecular mechanisms of apple scald development is essential for scald prediction and prevention. In this study, a genomics approach of suppressive subtraction hybridization (SSH) was applied to identify the differentially expressed genes which are potentially involved in the symptom development. Consistent with long-standing hypothesis that development of apple scald is associated with an imbalance in oxidative metabolism, several groups of apple genes encoding proteins functioning in oxidative metabolism, including lipoxygenase, oxidoreductase, and polyphenol oxidase were identified as up-regulated genes in tissue with initial symptoms after storage and during scald symptom development. Further functional analysis will further elucidate their specific roles in apple scald development.

Technical Abstract: Apple superficial scald (scald) is a recurring postharvest physiological disorder with significant economic impact. Elucidating the molecular mechanisms of apple scald development is essential for scald prediction and prevention. In this study, differentially expressed genes were identified using suppressive subtraction hybridization (SSH) for two types of apple peel samples, i.e. healthy tissue versus tissue with initial symptoms after storage and during scald symptom development. The most apparent groups of up-regulated genes in tissue showing initial scald symptoms are those encoding proteins functioning in oxidative metabolism, including lipoxygenase, oxidoreductase, and polyphenol oxidase encoding genes. This result is consistent with the long-standing hypothesis that development of apple scald is associated with an imbalance in oxidative metabolism. Several pathogenesis-related (PR) proteins encoding genes were also up-regulated, including apple allergens mal d 1/PR protein 10, apple allergens mal d 3/PR protein 14, PR protein 5 and PR-protein 8 encoding genes in the tissues with initial scald symptoms. Other up-regulated genes included those encoding transporter proteins such as acyl carrier protein, peptide transporter and putative ABC transporter. Also induced are several proteins related to stress responses including heat shock protein, osmotin-like protein and early-response to dehydration protein. Up to 30% of the identified genes were annotated as “unknown function” and or “hypothetical proteins”. Further functional analysis is needed to elucidate their roles in apple scald development.