Impatiens walleriana is a valued ornamental plant sensitive to drought stress. We investigated whether the foliar application of 2mM salicylic acid (SA) can protect potted I. walleriana plants from drought stress. The plants were divided into: watered plants, drought-stressed plants, watered plants treated with SA and drought-stressed plants treated with SA. The number of flowers and flower buds, relative water content (RWC), contents of malondialdehyde (MDA) and proline (Pro) and the activities of superoxide dismutases, catalases and peroxidases were recorded at different time points. Three dehydrin sequences were identified in de novo assembled leaf transcriptome: IwDhn1, IwDhn2.1 and IwDhn2.2. Drought stress caused wilting, floral abortion, reduction of RWC and increased MDA—an indicator of lipid peroxidation. In response to drought, Impatiens accumulated Pro and induced chloroplastic Cu/ZnSOD and two peroxidase isoforms. The most remarkable drought response was strong induction of IwDhn2.1 and IwDhn2.2. Rehydration restored RWC, Pro level, Cu/ZnSOD activity and dehydrins expression in drought-stressed plants approximately to the values of watered plants.SA had ameliorating effects on plants exposed to drought, including prevention of wilting, preservation of RWC, increased Pro accumulation, modulation of antioxidative activities and remarkable decrease of lipid peroxidation, but without effects on flowers’ preservation.

Fritillaria meleagris is a horticulturally and medicinally valuable bulbous plant that requires a period of low temperatures for proper growth and flowering. Since conventional methods of propagation are ineffective and very slow, tissue culture techniques offer an integrated approach to mass production of this valuable geophyte. In this study, we investigated the effects of various auxin–cytokinin combinations on different morphogenetic pathways in bulb scale culture. Bulbs obtained in vitro were cut longitudinally, and bulb scales were cultured for four weeks at 7 °C on MS medium supplemented with 6-benzylaminopurine (BAP) in combination with 2,4-dichlorophenoxyacetic acid (2,4-D) or α-naphthaleneacetic acid (NAA) at different concentrations in order to investigate the influence of plant growth regulators (PGRs) on different morphogenetic responses. Regeneration percentage, number of shoots per explant, shoot length, number of bulbs and number of somatic embryos were monitored weekly. After chilling, bulb scales were transferred to 24 °C, and all parameters were recorded again. Low PGR concentrations were very effective for shoot multiplication, yielding up to 5.5 shoots per explant. 2,4-D (at 2 mg/L) in combination with low BAP (0.25 mg/L) produced the highest number of bulbs (11.00 ± 0.00), while PGR-free medium was extremely effective in somatic embryo formation (13.50 ± 2.90). Detached somatic embryos and bulblets continued to grow and develop on fresh PGR-free medium. We present data demonstrating that low auxin–cytokinin concentrations and PGR-free medium provide an effective method for a combined morphogenetic pathway in F. meleagris that is suitable for large-scale propagation.

Hairy root cultures of lettuce (Lactuca sativa L.) were obtained by inoculation of cotyledonary leaves of in vitro lettuce seedlings (cvs. Nansen and Ljubljanska ledenka) with Agrobacterium rhizogenes A4M70GUS. Approximately in 96.7% cvs. Nansen and in 91.2% Ljubljanska ledenka inoculated explants produced hairy root when they were incubated on Murashige and Skoog (MS) half-strength medium without plant growth regulators. A total of 54% of all hairy root cultures expressed GUS activity. Every hairy root represented an independent transformation event. Line Ljubljanska ledenka 18 showed the highest biomass (5.5 times the biomass of control root). A PCR analysis of the genomic DNA confirmed the presence of marker and target genes in 15 hairy roots examined.

Impatiens walleriana L. shoots were inoculated with Agrobacterium rhizogenes A4M70GUS and the effects of genetic transformation on the catalase (CAT), superoxide dismutase (SOD) and peroxidase (POX) activities in wounded region of stems and unwounded leaves were evaluated 10, 24, 240 and 720 hours after inoculation. Following Agrobacterum infection activities of plant antioxidative enzymes changed in a time-dependent manner indicating that dynamic processes occurred during plant-Agrobacterium interaction, plant cell transformation and formation of hairy roots. Appearance of hairy roots on wound sites of shoots was observed ten days after inoculation with A. rhizogenes and the root induction frequency was 100%. Among selected hairy root lines significant differences in growth rate and biomass production were observed and an average 3-fold increase in biomass production was observed for the best growing hairy root line compared with the untransformed roots. PCR analysis showed presence of uidA, rolB, rolC and rolD genes in all analyzed I. walleriana L. hairy root lines, while amplification fragment of rolA gene was detected in 83.3% transformed lines. Efficient transformation protocol for I. walleriana L described in this work offer possibilities to generate hairy root cultures for in vitro propagation of plant viruses.