Calli were successfully induced from style explants of Crocus sativus L. on Murashige and Skoog's medium supplemented with -naphthalene acetic acid and 6-benzylaminopurine. Then they were divided into three different types based on developmental stages and pigmentation progress in induced stigma-like structures. RT-PCR method was set up using calli in different developmental stages to detect expression levels of CsLYC, CsBCH1, CsZCD and CsUGT2 genes for apocarotenoids biosynthesis via mevalonic acid pathway in C. sativus. The results obtained from in vitro investigation
of CsUGT2 expression levels in all three developmental stages were analyzed and compared with the expression levels of selected genes carried out on intact stigmas in vivo. Apparently, this gene was only expressed in the stage III of the three in vitro different SLSs developmental stages. Furthermore,
the expression levels of CsLYC, CsBCH1, CsZCD were detected in stage III with fully developed SLSs and were comparable with those of in red intact stigmas.