Production of micropropagated melon plantlets adapted to saline environment

An experiment was carried out to evaluate the behaviour on salt stress induced by sodium chloride of two melon clones obtained from micropropagation. Since arbuscular mycorrhizal (AM) fungi seem to increase salt tolerance in some crops, at acclimatisation melon plantlets were mycorrhizal with an AM fungus. The root systems of both mycorrhizal and non mycorrhizal plants were exposed to increasing salt concentrations and then placed in distilled water to study the wilting response and the recovery of plants. Observations were made on several morphological parameters, in particular to verify the modification of root system morphology caused by AM fungus, as demonstrated already by several studies. The analysis of infected roots was carried out following Phillips and Hayman's protocol (1970). Afterwards, the specimen was read using an optical microscope

Plant development and synthesis of essential oils in micropropagated and mycorrhizated plants of Origanum vulgare L. ssp. hirtum (Link) Ietswaart

Biomass production of micropropagated oregano was induced by inoculation with the fungus Glomus viscosum. The effects of arbuscular mycorrhizal (AM) symbiosis on morphological and metabolic variations of regenerated oregano plants were investigated at different growth stages. AM greatly increased parameters such as plant leaf area, fresh and dry weight, number of spicasters and verticillasters in infected plants. An increase of the gland density, especially on the upper leaf epidermis, was also observed following the physiological ageing of the tissues. The in vitro plants of O. vulgare ssp. hirtum described in this study provided a qualitatively and quantitatively good source of essential oils that have a chemical profile comparable to that of the control mother plants with carvacrol as the main compound

Alleviation of salt stress in Cynara cardunculus L. var. scolymus fiori by arbuscular mycorrhizal fungi

Research was carried out in order to evaluate the effect of mycorrhizal fungi in improving artichoke tolerance to salinity stress induced by sodium chloride. In fact, several studies have shown that arbuscular mycorrhizal (AM) fungus symbiosis enhances salt tolerance in some crops. The experiment was carried out with seedlings of artichoke cultivar '044' (Cynara cardunculus L. var. scolymus), treated or not with AM fungi (Glomus viscosum) at sowing. The root systems of both mycorrhizal and non mycorrhizal plantlets were carefully washed to remove the substratum and exposed to distillated water (control) and saline water (13 and 26 dS m-1) obtained by adding NaCl. The wilting trend was studied defining wilting indexes on the basis of visual characteristics. When the wilting had stabilized, the plant roots were washed in distilled water and then transferred to glass jars with distilled water until the recovery of the plantlets. The results indicate that AM fungi improve tolerance to salinity stress, confirming the beneficial effect of mycorrhizal fungi in abiotic stresses also for artichokes. © ISHS

Regeneration through organogenesis from leaves of Helichrysum italicum (Roth) G. Don

Helichrysum italicum (Roth) G. Don is an aromatic plant of the Asteraceae family that grows spontaneously in Mediterranean areas. Among the very large number of phytoproducts that can be obtained from this species, essential oils are successfully used both in cosmetics and in pharmaceutical preparations for their antiinflammatory and antimicrobial activities. The main constrain for industrial sector is that spontaneous plants are extremely variable. The presence of an innovative technique that provides selected and uniform plants could be a good strategy for the success of this interesting species. Leaf fragments of H. italicum micropropagated plants were used as explant source. The explants were cultured in a medium containing MS macronutrients (Murashige and Skoog, 1962) and micronutrients from Nitsch and Nitsch (1972), Fe-EDTA (30 mg L-1), thiamine HCl (0.4 mg L-1), myoinositol (100 mg L-1), sucrose (30 g L-1) and agar (7 g L-1). For organogenesis induction, basal medium supplemented with thidiazuron (TDZ 0.1, 0.5, 1, and 2 mg L-1) alone or in combination with naphthalene acetic acid (NAA 1 mg L-1) were used. The results showed that H. italicum has a great organogenic capacity: the explants formed adventitious shoots for each treatment through the callus formation or directly from the leaves on the hormone-free medium. Rooting frequency was near 100% on leaves cultured in the hormone-free medium. In conclusion, leaf explants give encouraging results in organogenesis allowing to exploit this technique in commercial production of H. italicum extracts

Mycorrizathion on micropropagated artichoke

Regenerated shoots, rooted or not, obtained by micropropagation were transplanted into pots with a substratum containing crude arbuscolar mycorrhizal (AM) inoculum and compared with untreated plants to ascertain whether an effective mycorrhizal symbiosis could be obtained by inoculation with appropriate AM fungi early on during a post vitro weaning stage to improving the rooting rate and survival at outplanting The results show mycorrhizal infection that facilitates the adaptation to mist greenhouse conditions markedly. Moreover the presence of the inoculated fungus influences the root production in unrooted microplants, allowing their survival. Growth differences between mycorrhizal and control plants were very large, confirming the importance of mycorrhizal inoculation for micropropagated plants