Image Analysis for Detection of Crocin Content and Growth Index of Saffron Corm Derived Cells Under Different Physiological and Chemical Conditions

The valuable saffron metabolites have encouraged researchers to study their laboratory production. In this study, two experiments have been designed to optimize saffron corm callogenesis in-vitro conditions and assessed the application of image analysis to address some characteristics of calli without cell destruction. Effect of physiological age of the corm, different types of media, and plant growth regulators (PGRs) with different concentrations as independent variables were investigated on cell growth index, the redness intensity (a*value) of callus and the percentage of black spot as dependent variables. Results showed that the mature corm-derived explants on Gamborg (B5) medium create the best callogenesis and production of red-colored cells with the least black spot. It was also revealed that naphthalene acetic acid (NAA), (2 mg/L) in combination with 6-Benzylaminopurine (BA) (1 mg/L) increased the growth index to 1.14. In contrast, the combination of indole-3-acetic acid (IAA), (2 mg/L) or indole-3-butyric acid (IBA), (10 mg/L) with kinetin (KIN), (1 mg/L) was the most effective PGRs for the production of red cells. The HPLC results confirmed that the red color of the calli was related to crocin presence. It is concluded that although the cultivation of saffron mature corms in the B5 medium is the most suitable option for biomass growth and crocin production, the choice of PGRs varies depending on the purpose of the culture (biomass or crocin production). Moreover, image analysis can be considered as a promising, alternative, un-destructive, and fast method for estimating the cell growth index and crocin content.