Kinetin Enhanced Linalool Production by in vitro Plantlets of Lippia alba

Mentha piperita L. Micropropagation and the Potential Influence of Plant Growth Regulators on Volatile Organic Compound Composition

Due to the industrial use of Mentha piperita L. (peppermint), it is important to develop an optimal method to obtain standardized plant material with specific quality parameters. In vitro cultures may allow the production of desirable odor-active compounds (OACs) and improve their share in the plant aroma profile. There are two types of explants that are commonly used, apical meristems and nodal segments. In this study, the best overall effects were shown to be produced by the combination of MS medium with the addition of 0.5 mg·dm⁻³ indolyl-3-butyric acid. In this case, a very high degree of rooting was found (97% for apical meristems, 100% for nodal meristems), lateral shoots were induced in 83% of both types of explant, and the content of OACs in the plant aroma profile increased significantly, especially menthofurolactone and cis-carvone oxide, responsible in this case for a characteristic mint-like aroma. The comparison of the volatile organic compounds (VOCs) obtained from plants of different origin by GC-MS showed no significant differences in their qualitative composition. Moreover, in-vitro-cultivated peppermint on a medium containing 0.5 mg·dm⁻³ 2-isopentinloadenine and 0.1 mg·dm⁻³ indolyl-3-acetic acid showed significant amounts of menthofurolactone in its VOC composition.

Kinetin establish the volatile chemical profile after rhizome dormancy is released in Curcuma zedoaria (Christm.) Roscoe

The aim of this work was to provide information about kinetin effects on chemical volatile profile of Curcuma zedoaria (Christm.) Roscoe after several days of plant dormancy release. Rhizomes of C. zedoaria were immersed in four kinetin concentrations (0, 50, 100, 150 mg ml^-1, n = 12 by each concentration) for 30 min. After 240 h of treatment, root length (mm), bud break (%) and bud speed index (BSI) were measured, and three rhizomes at 24 h and 240 h were collected for chemical volatile profile analysis by application of headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). Kinetin does not alter morphological aspects of the bud dormancy releasing, but drastically changes metabolic aspects of volatile production on C. zedoaria rhizomes, by the selection of several monoterpenes, such as camphene, sabinene, isoborneol, borneol, 1,8-cineole. We assume that kinetin application maintain monoterpene production as a consequence of its signaling over dormancy release.

Influence of growth regulators in biomass production and volatile profile of in vitro plantlets of Thymus vulgaris L

In vitro shoots of thyme (Thymus vulgaris L.) were established, and the effects of the auxin indole-3-acetic (IAA) acid and the cytokinins benzyladenine (BA), zeatin (ZEA), and kinetin (KIN) at 1.0, 5.0, and 10.0 microM on rooting, biomass production, and volatile compounds production by these plants were investigated. The volatiles were extracted by solid phase microextraction (SPME) and analyzed by gas chromatography. The highest biomass shoot growth was obtained with BA at 5.0 microM, while IAA at all concentrations tested achieved 100% rooting frequency. The three major compounds were gamma-terpinene (22.8-38.8%), p-cymene (13.8-27.9%), and thymol (6.5-29.0%). Quantitative changes of these compounds were observed in response to the effect of varying growth regulators concentrations in the culture medium. Growing Thymus vulgaris L. plants in media supplemented with IAA at 1.0 microM increased volatile compounds such as thymol by 315%. Nevertheless, the same major compounds were produced in all treatments and no qualitative changes were observed in the volatile profile of thyme plants.