Irrigation effects on pds and bell genes expression of the Iranian Saffron

Saffron (crocus sativus l.) is an indigenous and the most valuable and marginal plant in iran, however,limited know ledge exists on its molecul ar bio logy. the importa nce 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 croc in. two genes, bch and pds, have essen tial role in carotenoid production . in this study, the effect of four different irriga tion regimes was evaluated on the expression of bch and pds genes. semi-quantitative rtpcr showed no significan t difference in the expre ssion leve ls of genes of interest related to the internal standard ( i8s rrna). results of real-time pcr assays showed that the expressio n of bch and pds genes were affected by irriga tion treatments as thei r expression decreased in irriga ted plants in comparison to non irrigated ones, exept for one irrigat ion treatment (one irrigation in september) where the pds gene expression showed higher level. however, the expression profi le of the genes was almost the same in all treatments. the comparison between results of two tech niques indicated that the real-time pcr is more acc urate for determi nation of the level of transcr ipt in the iranian sa ffron. it was interesting that by decreasing of irrigation, the expression leve l of these two genes increased indica ting that abiotic stress and drought can affect on the gene expression relating to the saffron color.