س.ع.پیغمبری

MicroRNAs are endogenous noncoding RNA that play vital roles in all plant cellular metabolic processes by mediating target gene expression. To date, miRNAs in Taraxacum spp., which is an important industrial plant, have remained largely unknown. In the present study, 970 miRNAs from 399 families were identified in Taraxacum spp by conducting computational approaches. The most frequent miRNAs in Taraxacum spp was miR5021. According to the KEGG results, miR5021, miR838, and miR1533 are related to the terpene biosynthesis pathway, while miR5015b, and miR1436 are involved in the starch and sucrose biosynthesis pathways. Quantitative real-time PCR assay was performed to validate the expression levels of five predicted miRNAs and 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase (HMGCR) and invertase as the target genes. Results indicated that the highest relative expression of miR1533 and miR1436 occurred in the flower, while the highest transcripts levels of miR5015b were observed in the stem. In addition, the higher relative expression level of the miR5021 and miR838 was consistent with the lower expression level of the HMGCR gene in all tissue, suggesting that miR5021 and miR838 are involved in regulating HMGCR gene expression. Since mevalonate pathway is the main source of isopentenyl pyrophosphate, which is used in the synthesis of rubber, miR5021 and miR838 play an important role in the production of rubber by regulating the expression of HMGCR enzyme. These findings will accelerate future perspective studies on the regulatory mechanisms of miRNAs in Taraxacum kok-saghyz.

Chicory (Cichorium intybus L.) is a typical Mediterranean plant distributed throughout the world and has different commercial uses such as salad, forage, inulin production, and coffee substitute. Health promoting characteristics of inulin as a prebiotic compound led to its biosynthesis pathway discovery. Two enzymes, namely, 1-SST and 1-FFT, are involved in inulin biosynthesis during normal phase. By cold nights or other factors, 1-FEHs enzymes degrade inulin to fructosyl units. To compare the strength of function of these genes in a wild type genotype with root type cultivar (Orchies) of chicory at three stages, i.e. 60, 90, and 120 days after seed planting, relative expression of those genes along with their corresponding metabolites were assessed using RT-qPCR and HPLC. Expression results showed that, unlike Orchies cultivar, relative expression of 1-SST in wild type genotype was ascending, relative expression of 1-FFT was very low and constant and there were high levels of relative expression of 1-FEH I gene during growing season due to flowering initiation. Also, glucose and fructose concentrations were upward, as result of 1-SST and 1-FEH I enzymes activity in wild type genotype, respectively. Degree of Polymerization (DP) of produced inulin had almost no increase due to low function of 1-FFT enzyme in the wild type genotype (DP 10 as expression of 1-SST decreased during growing season. So, it is possible to make inulin pathway in root type chicory cultivars more efficient by expanding and overexpressing 1-SST function using such wild resources through backcross breeding or biotechnology methods.