Cadmium accumulation and its effect on the in vitro growth of woody fleabane and mycorrhized white birch.

The effect of Cd on woody fleabane (Dittrichia viscosa (L.) Greuter) and white birch (Betula celtiberica Rothm. & Vasc.) was examined. Woody fleabane and white birch were grown in vitro in Murashige, T., Skoog, F., [1962. A revised medium for rapid growth and bioassays with tobacco tissue cultures. Physiol. Plant. 15, 473-479] (MS) plus Cd (10 mg Cd kg(-1)) and except for root length in white birch, plant development was inhibited when Cd was added. Cd accumulation in above-ground tissues showed differences among clones, reaching 1300 and 463 mg Cd kg(-1) dry wt. in selected clones of woody fleabane and white birch, respectively. Tolerance of Paxillus filamentosus (Scop) Fr. to Cd was also examined before mycorrhization. Plants of mycorrhized white birch grown in the presence of Cd had a better development and accumulated more Cd in their shoots than the non-mycorrhized ones. The use of selected clones of woody fleabane and the mycorrhization of white birch enhance extraction efficiency from contaminated soils in phytoremediation programs.

Cryopreservation of in vitro-grown shoot-tips of hop (Humulus lupulus L.) using encapsulation/dehydration.

A cryopreservation procedure using encapsulation/dehydration was established for shoot-tips obtained from in vitro-grown shoots of hop. After dissection, shoot-tips were encapsulated in medium with alginate and 0.5 M sucrose. Optimal conditions consisted of preculture for 2 days in solid medium with 0.75 M sucrose, or in increasing sucrose concentrations, desiccation for 4 h with silicagel in a flow cabinet (16% water content) followed by rapid freezing and slow thawing. Shoot recovery after freezing 60 min in liquid nitrogen was around 80%. No phenotypical changes were observed in the recovered plants from cryopreserved shoot-tips growing in the field.

Analysis of 3-indolylacetic acid and abscisic acid by high-performance liquid chromatography and gas-liquid chromatography.

A method of analysis of 3-indolylacetic acid (IAA) and abscisic acid (ABA), allowing the simultaneous extraction of both regulators from plant material, has been developed. The method involves extraction with methanol, isolation of the acid fraction, diazomethane methylation, separation of the hormones through reverse-phase preparative high-performance liquid chromatography, and quantification of both compounds by gas-liquid chromatography. The recovery percentage at each step was monitored with radioactive compounds added at the beginning of the process. The final recovery was 70% for IAA and 96% for ABA. The method was applied to the analysis of the IAA and ABA content of stems of hazel (Corylus avellana L.).

"In vitro" filbert (Corylus avellana L.) micropropagation from shoot and cotyledonary node segments.

Plantlets were successfully regenerated from shoot and cotyledonary node segments excised from 20 day old filbert seedlings. In both cases the optimum initiation and elongation of shoot buds was obtained after 15 days culture in 1/2K(h) medium plus BAP (25 µM) followed by 20 days culture in the same medium in presence of a reduced BAP concentration (0.5 or 2.5 µM).Maximum of functional roots were readily formed after 5 days of submersion of the basal end of shoots in 1/2K(h) liquid medium plus IBA (50 µM), then transferred to a fresh 1/2K(h) solid medium for a further 15 days. Following these two consecutive steps, root initiation and development was achieved in 80% of the explants.The histological origin of neoformed organs was studied.

Peroxidase and IAA oxidase in germinating seeds of Cicer arietinum L.

Peroxidase and indole acetic oxidase (IA oxidase) activities in seeds of Cicer arietinum L. were studied at 72 h of germination. Both activities behaved differently in relation to optimum pH, stability against temperature and time of storage of 4 degrees C. Disc electrophoresis on polyacrilamide gel showed the existence of five anionic and three cationic isoenzymes with peroxidase activity by using benzidine as substrate; three of the anionic isoenzymes and one cationic isoenzyme possessed a simultaneous IAA oxidase activity as well.