Cardosins are plant aspartic proteinases (APs) isolated from the flowers of Cynara cardunculus L. (cardoon) and are responsible for their milk-clotting activity used to manufacture ewe’s cheese. Cardosin A is mainly accumulated in protein storage vacuoles of the stigmatic papillae being suggested a possible role in pollen-pistil interaction. Cardosin B has been localized to the extracellular matrix of stylar transmitting tissue and a role in the remodelling or degradation of pistil extracellular matrix, during pollen tube growth, has been suggested. Also, cardosin B localization is closely correlated with programmed cell death (PCD) events in the nucellus of C. cardunculus, suggesting involvement in ovule and embryo sac development. Therefore, both cardosin A and B may fulfil important roles during sexual reproduction of the plant. In seeds APs may participate in protein hydrolysis, but, as they are present since early seed maturation they may take part both in zymogen activation and localised PCD in seed tissues, having a crucial role in the regulation of protein degradation and embryo nourishing. In the embryo cardosin A precursor form is accumulated in protein bodies and cell walls, a different localization from the described in cardoon flowers, suggesting a tissue-dependent pattern of accumulation of the protein. Furthermore, APs Plant Specific Insert seems to have a preponderant role in membrane reorganisation events and during water uptake and solute leakage, which supports the recently proposed bifunctional role of the AP precursor molecule. In this review, we intend to characterise cardosins developmental regulation in organs of C. cardunculus from the flower to post embryonic development and explore the putative roles assigned to these APs.
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