irrigation effects on pds and bch genes expression of the iranian saffron

saffron (crocus sativus l.) is an indigenous and the most valuable and marginal plant in iran. however, limited knowledge exists on its molecular biology. the importance of this plant is due to the color, flavor and medicinal properties of its red stigmas. saffron stigmas contain a high amount of carotenoids such as crocetin and crocin. two genes, bch and pds, have essential role in carotenoid production. in this study, the effect of four different irrigation regimes was evaluated on the expression of bch and pds genes. semi-quantitative rtpcr showed no significant difference in the expression levels of genes of interest related to the internal standard (18s rrna). results of real-time pcr assays showed that the expression of bch and pds genes were affected by irrigation treatments as their expression decreased in irrigated plants in comparison to non irrigated ones, exept for one irrigation treatment (one irrigation in september) where the pds gene expression showed higher level. however, the expression profile of the genes was almost the same in all treatments. the comparison between results of two techniques indicated that the real-time pcr is more accurate for determination of the level of transcript in the iranian saffron. it was interesting that by decreasing of irrigation, the expression level of these two genes increased indicating that abiotic stress and drought can affect on the gene expression relating to the saffron color.