Phenotypic Characterization of Sink-source Relationship Between Mother and Daughter Corms in Saffron -Crocus sativus-

Abstract

affron -Crocus sativus-, the world’s most expensive spice and herbal medicine, is geographically distributed throughout the Mediterranean, East Asia, and Irano-Turanian regions. All of these areas have low annual rainfall, cold winters, and hot summers which is well suited for saffron cultivation. In order to test the potential for culturing saffron as a specialty crop in the Midwest region of the United States, we have been studying the physiological, biochemical, and developmental fitness of the plants grown in Minnesota over the past two years. Here, we report our observations of the developmental process of saffron daughter corms without leaves and photosynthesis, which suggests a mechanism that saffron adapts to grow under drought, cold, and hot environments. We found that the daughter corms can directly initiate and grow by consuming nutrients from their mother corm. Tissues taken from different parts of the mother and daughter corms confirmed that starch granules are the principle constituent of the corms. A prominent vascular tissue structure was observed in the junction between mother and daughter corms, staining of the tissue with different dyes showed conversion of starch granules to sucrose in the cells of mother corms and sucrose to starch granules in the cells of daughter corms. Further molecular and biochemical investigation for this process is needed in order to advance our understanding of the feasibility of growing saffron in the Midwest as a specialty crop.