The Effect of Carvacrol, Thymol, BA and NAA on in vitro Regeneration in Fritillaria imperialis L

Fritillaria imperialis L. is an ornamental and medicinal plant native to mountainous regions of Iran. This plant genetic resource is in danger of extinction, Because of grazing livestock and pest outbreaks. Therefore, micro propagation of Fritillaria through in vitro regeneration is essential for conservation and commercial production. Thymol and Carvacrol are one of the main essential oil compounds in family Lamiaceae.
Material and Fritillariaimperialis L. bulbs in dormancy stage obtained from mountainous regions of Lorestan in Iran and were placed in cold room at +4 °C for 4-6 weeks. Then, Bulbs were surface-sterilized with 70% ethanol for 45 s followed by immersion in 5% (v/v) NaOCl solution for 20 min with gentle agitation, and then rinsed three times in sterile double distilled water. Present study was conducted in two separate experiments. In first experiment, effect of different concentration of Thymol and Carvacrol and in second experiment, different concentration of NAA and BA on in vitro characteristics of Fritillaria was evaluated. Explants (1× 1 cm) prepared from the lower third of scales with basal plate and were placed in MS basal medium supplemented with different concentrations of Thymol (50, 100, 150 and 300 ppm), Carvacrol (10, 100, 500 and 100 ppm), BA (1, 2 and 4 mg/l) and NAA (1, 2 and 4 mg/l).All cultures were incubated in a growth chamber at 24±2°C, and a photosynthetic photon flux of 40-60 μmol m–2 s–1 was provided by cool white fluorescent lamps with a 16-h photoperiod. This experiment wascarried out in completely randomized designs with fivereplications. Analysis of variance showed that Thymol and Carvacrol were not effective on number of new bulblets but had significant effects on bulb diameter, number and length or roots, number and length leaves and callus induction and diameter of callus obtained from scales (P< 0.05). The highest rate (3 bulblets) of bulblets formation was obtained fromMS medium supplemented with 50 ppm Thymol that showed significantly difference from other treatments. Medium containing 10 ppm Carvacrol gave the highest Bulblet formation (2.5 bulblets) between Carvacrol treatments. Investigation of rooting was done by assessment of the number and length of roots. Mean comparison of the effect of cultivar type on root number showed that the largest number of roots per explant was obtained fromMS medium containing 50 ppm Thymol. Lowest number of roots observed in mediums supplemented with 300 ppm Thymol and 100 ppm Carvacrol. The best medium for increasing the root length per explant (10.90 cm) was MS medium supplemented with 100 ppm Carvacrol, while the least increasing in root length per explant observed from culture mediums contained 300 ppm Thymol and 100 ppm Carvacrol. Also, the largest number of leave formation obtained from culture medium supplemented with 50 ppm Thymol that significantly higher than other treatments. Statistical analysis (ANOVA) of the data showed that high frequency callus induction and formation occurred in MS mediums contained 50, 100 and 150 ppm Thymol and 10 ppm Carvacrol and culture mediums supplemented with 300 ppm Thymol and 1000 ppm Carvacrol showed least callus induction. In contrast, largest callus diameter observed in culture mediums supplemented with 300 ppm Thymol and 500, 100 ppm Carvacrol.
Statistical analysis of results showed that different concentrations of BA and NAA had significant effects on bulblets number and bulblets diameter (P