Semi-quantiative real time polymerase chain reaction (SQ-RT-PCR) was applied to study Limonene synthase (LS) gene expression pattern and the response to different concentrations of manganese in different organs of cumin (Cuminum cyminum L.). The results revealed that the gene was expressed in very small (< 2 mm) and small (3-4 mm) flowers and also in shoots, while it was not expressed in roots, leaves, medium (4-5 mm) and larger flowers. The highest level of gene expression was observed in shoot and very small flowers. Partial sequencing of LS gene in cumin revealed 68-88% identical to that of some other plants. To determine the effect of manganese on LS gene expression, the plants were exposed to different concentrations of manganese (0, 40, 80 and 160 ppm) as spray by applying two methods: T1- Alternatively spraying at late vegetative stage besides blooming; T2- Spraying only at blooming. LS gene expression was increased considerably under 80 ppm concentration of Mn at blooming and reduced remarkably under 40 ppm in both methods and at 160 ppm in T1 method in comparison with controls. Anatomical studies indicated that essential oil ducts were located not only in the fruits tissue but also in the shoot surprisingly. Overall, results of this research reveal limonene synthase gene expression in cumin for the first time. In addition, use of 80 ppm of Mn at blooming can be considered as optimum concentration to increase LS gene expression. Existence of oil ducts on the shoot of this plant is a remarkable finding for further studies.
Key words: Cuminum cyminum L., Limonene synthase gene, manganese.
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