Cell Biology

Macromolecules, proteins, lipids, and other small molecules, such as carotenoids can be studied within different tissues and organelles using an array of in vitro and in vivo methodologies. In the case of tomato and other fleshy fruit the predominant organelle in ripe fruit is the chromoplast. The characteristic feature of this organelle is the presence of pigments, carotenoids at high levels. In order to fully understand the underlying biological mechanisms that operate within the chromoplast, it is necessary to perform studies at the subchromoplast level. This protocol allows the separation of plastoglobules (lipoprotein particles, which are coupled to thylakoid membranes in the chloroplasts) and membranes (thylakoid, envelope-like) of chromoplasts through a sucrose gradient. The subchromoplast compartments can then be analysed independently. Comparisons between mutant/transgenic genotypes and their backgrounds can be performed accurately with simultaneous processing during the same fractionation run. The procedure was initially developed for ripening tomato fruit but translation to sweet and hot pepper has been shown.