Establishing a Long-Term Cultivated Embryogenic Culture of Papaver rupifragum Boiss. & Reut. and Its Cytological and Biochemical Study

Abstract

An embryogenic culture of poppy Papaver rupifragum Boiss. Reut., which was initiated on the roots of seedlings grown from seeds on MS medium with the addition of 1 mg/L IBA, was obtained for the first time. Subsequent maintenance of the embryogenic culture was carried out on a hormone-free MS medium. Long-term cultivation and preservation of the embryogenic capacity of the culture (more than 5 years) was supported by cycles of adventitious embryoidogenesis, including the formation of callus on preexisting embryoids and the induction of new embryoids from their subsurface cells. In this regard, the resulting P. rupifragum culture can be considered as a differentiated culture in which the callus stage is an intermediate stage of development. It has been established that the surface of newly formed embryoids is covered with a surface network of extracellular matrix formed by polysaccharides, lipids, and terpenes. Histological analysis showed that embryogenic P. rupifragum culture is characterized by the formation of complexes of fused embryoids (CFE), which presumably arise either as a result of cleavage polyembryony or during the synchronous development of nearby embryoids. A study of the histology and ultrastructure of CFE revealed that the fusion of embryoids is caused by disturbances in the formation of the epidermis and cuticle. Histochemical studies have established that embryogenic P. rupifragum culture synthesizes and accumulates triacylglycerides, polysaccharides, phenolic compounds (PCs), terpenes, and alkaloids. It has been shown that the quantitative and qualitative composition of the PCs and alkaloids of the P. rupifragum culture depended on the age of the culture and its differentiation, adjustable by growing conditions (light, dark). Differentiated embryogenic P. rupifragum culture retains the ability to form embryoids on a hormone-free MS medium for a long time of cultivation and can be the basis for the further development of biotechnological methods for producing medicinal compounds for cosmetology and pharmacology.