Gene Expression Patterns of CsZCD and Apocarotenoid Accumulation during Saffron Stigma Development

Crocus sativus L., otherwise known as saffron, is a highly prized plant due to its unique triploid capability and elongated stigmas, contributing to its status as the costly spice globally. The color and taste properties of saffron are linked to carotenoid elements including cis- and trans-crocin, picrocrocin, and safranal. In the research carried out, we dedicated our attention to the gene CsZCD, an important player in the formation of apocarotenoids. Through the application of real-time polymerase chain reaction to RNA purified from saffron stigmas at various growth phases, it was determined that the peak expression of the CsZCD gene coincided with the red stage, which is associated with the highest concentration of apocarotenoids. The data showed a 2.69-fold enhancement in CsZCD gene expression during the red phase, whereas a 0.90-fold and 0.69-fold reduction was noted at the stages characterized by orange and yellow hues, respectively. A noteworthy observation was that CsZCD's expression was three times that of the CsTUB gene. Additionally, relative to CsTUB, CsLYC displayed 0.7-fold and 0.3-times expression. Our investigation provides insight into the governance of CsZCD during stigma maturation and its possible influence on the fluctuation in apocarotenoid content. These discoveries carry significance for the industrial production of saffron spice and underscore the importance of additional studies on pivotal genes participating in the synthesis of apocarotenoids.