[In vitro micropropagation and chemical analysis of some wild Iris species in Syria]

wild Iris species found in Syria are characterized by special, beautiful form and have a great importance in applied studies for genetic biodiversity . Iris plants respond poorly to propagation by seeds, and is rarely found in nature therefore , a new trend has evolved to propagate these species through tissue culture technique to preserve it from deterioration and to study the possibility to use them as a medical or ornamental plant. In this investigation, a technique has been established, for the first time in Syria for vegetative micropropagation of Iris nigricans and Iris aurantica. Some growth hormones and growing media were experienced to determine the best conditions in multiplication and rooting stages. In addition, chemical analysis of essential oil by gas chromatography (GC) and mass spectrometry (MS) were applied. Bases of leaves and shoot tips of rhizomes (after surface disinfection by chlorox 3%) were cultured on solidified MS medium containing 30 g/l sucrose supplied with 2 mg/l BAP, and 0.2 mg/l IBA. Results showed, after one month of culture, that using shoot tips of rhizomes resulted in the highest growth percentage (35.76 %) in initial stage , with significant differences comparing with base of leaves explants. meanwhile, no significant differences were recorded between species (I.nigricans and I.aurantica). In the multiplication stage, MS media resulted in the highest multiplication rate and shoot length with significant difference compared with Heller media. The concentration of 5 mg/l of BAP achieved the highest average (13.36 ) and good shoot length (4.73 cm) in Iris nigricans, but in Iris aurantica the concentration 3 mg/l of BAP resulted in highest multiplication rate (3.43) with significant difference compared with the control (1.25) . Subculture of the plantlets on the same medium resulted in increasing multiplication rate and shoot length for the two species ( I. nigricans and I.aurantica). In rooting stage, results showed that Iris nigricans produced the highest root percentage (81.72 %) with significant difference compared to Iris aurantica (66.44 %) . The highest root percentage (89.25%) was observed when using the concentration 3 mg/l of IBA. Results of root number showed no significant difference between the two species of Iris. The highest root number (3.57) was recorded when using the concentration 3 mg/l IBA with significant difference compared with the control (1.09 ), meanwhile, the control resulted in the highest root length (4.77 cm). Observation indicated that 100 % of rooted plantlets were successfully acclimatized and developed into plant after one month of transferring them to pots in Iris nigricans . meanwhile, percentage of success was 86.95% in Iris aurantica. plantlets were cultured in greenhouse to study their development in the natural conditions. Essential oil from rhizomes of Iris species were analyzed by GC-MS . The results showed that : 23 volatile components were identified and determined in the oil of the rhizomes in Iris germanica,18 in Iris nigricans and 19 chemicals in Iris aurantica. Myristic acid was detected as the main fatty acid in the oil from all species , it was 61.42 % in Iris germanica, 80.33 % in Iris nigricans and 70.67 % in Iris aurantica. The other compounds were Dodecanoic acid , Decanoic acid, Hexadecanoic acid methyl ester ¡ 9-Octadecenoic acid methyl ester