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New Publication: Proteomics of Cacao Fruit, Embryo and Seed Development

Posted: April 15, 2015

Manuscript published by visiting scientist Nicolas Niemenak from Cameroon, seen here to the right of the Nittany Lion in 2011 at Penn State.

Manuscript published by visiting scientist Nicolas Niemenak from Cameroon, seen here to the right of the Nittany Lion in 2011 at Penn State.

Niemenak, N., Kaiser, E., Maximova, S. N., Laremore, T. & Guiltinan, M. J. Proteome analysis during pod, zygotic and somatic embryo maturation of Theobroma cacao. Journal of Plant Physiology 180, 49-60, doi:http://dx.doi.org/10.1016/j.jplph.2015.02.011 (2015).

Two dimensional electrophoresis and nano-LC–MS were performed in order to identify alterations in protein abundance that correlate with maturation of cacao zygotic and somatic embryos. The cacao pod proteome was also characterized during development. The recently published cacao genome sequence was used to create a predicted proteolytic fragment database. Several hundred protein spots were resolved on each tissue analysis, of which 72 variable spots were subjected to MS analysis, resulting in 49 identifications. The identified proteins represent an array of functional categories, including seed storage, stress response, photosynthesis and translation factors. The seed storage protein was strongly accumulated in cacao zygotic embryos compared to their somatic counterpart. However, sucrose treatment (60 g L−1) allows up-regulation of storage protein in SE. A high similarity in the profiles of acidic proteins was observed in mature zygotic and somatic embryos. Differential expression in both tissues was observed in proteins having high pI. Several proteins were detected exclusively in fruit tissues, including a chitinase and a 14-3-3 protein. We also identified a novel cacao protein related to known mabinlin type sweet storage proteins. Moreover, the specific presence of thaumatin-like protein, another sweet protein, was also detected in fruit tissue. We discuss our observed correlations between protein expression profiles, developmental stage and stress responses.