Olaya Pérez-Tornero

Different media requirements for micropropagation of apricot cultivars.

Factors affecting in vitro propagation of several apricot cultivars were studied. The effect of nutrient media and BA concentration were strongly genotype dependent. Generally, best results were achieved with Quoirin and Lepoivre (1977) and a modification of WPM macronutrients (Lloyd and McCown, 1981). Optimum BA concentration was different for each cultivar but best results were obtained between 1.78 and 3.11 μM. Apricot shoots rooted well with different concentrations of IBA but most shoots showed symptoms of apical necrosis that could be overcome by dipping the shoot tips in solutions of 22.2 or 44.4 μM of BA prior to transfer to rooting medium.

Control of hyperhydricity in micropropagated apricot cultivars

SummaryThe effects of different factors on the control and reversion of hyperhydricity during the in vitro propagation of Prunus armeniaca were studied. Treatments that decreased the hyperhydricity but did not affect micropropagation rates were the use of the bottom cooling system for 1 or 2 wk and agargel as gelling agent in ‘Helena’, whereas the best results were obtained with the bottom cooling system for 2 wk and the use of 0.8% agar as gelling agent in ‘Lorna’. Hyperhydric shoots reverted to normal after keeping them for 3 wk in the bottom cooling system.

Improving knowledge of plant tissue culture and media formulation by neurofuzzy logic: a practical case of data mining using apricot databases.

Plant tissue growth can be regulated and controlled via culture media composition. A number of different laborious and time-consuming approaches have been used to attempt development of optimized media for a wide range of species and applications. However, plant tissue culture is a very complex task, and the identification of the influences of process factors such as mineral nutrients or plant growth regulators on a wide spectrum of growth responses cannot always well comprehended. This study employs a new approach, data mining, to uncover and integrate knowledge hidden in multiple data from plant tissue culture media formulations using apricot micropropagation databases as an example. Neurofuzzy logic technology made it possible to identify relationships among several factors (cultivars, mineral nutrients and plant growth regulators) and growth parameters (shoots number, shoots length and productivity), extracting biologically useful information from each database and combining them to create a model. The IF-THEN rule sets generated by neurofuzzy logic were completely in agreement with previous findings based on statistical analysis, but advantageously generated understandable and reusable knowledge that can be applied in future plant tissue culture media optimization.

Alleviation of salt stress in citrus seedlings inoculated with arbuscular mycorrhizal fungi depends on the rootstock salt tolerance

Seedlings of Cleopatra mandarin (Citrus reshni Hort. ex Tan.) and Alemow (Citrus macrophylla Wester) were inoculated with a mixture of AM fungi (Rhizophagus irregularis and Funneliformis mosseae) (+AM), or left non-inoculated (-AM). From forty-five days after fungal inoculation onwards, half of +AM or -AM plants were irrigated with nutrient solution containing 50 mM NaCl. Three months later, AM significantly increased plant growth in both Cleopatra mandarin and Alemow rootstocks. Plant growth was higher in salinized +AM plants than in non-salinized -AM plants, demonstrating that AM compensates the growth limitations imposed by salinity. Whereas AM-inoculated Cleopatra mandarin seedlings had a very good response under saline treatment, inoculation in Alemow did not alleviate the negative effect of salinity. The beneficial effect of mycorrhization is unrelated with protection against the uptake of Na or Cl and the effect of AM on these ions did not explain the different response of rootstocks. This response was related with the nutritional status since our findings confirm that AM fungi can alter host responses to salinity stress, improving more the P, K, Fe and Cu plant nutrition in Cleopatra mandarin than in Alemow plants. AM inoculation under saline treatments also increased root Mg concentration but it was higher in Cleopatra mandarin than in Alemow. This could explain why AM fungus did not completely recovered chlorophyll concentrations in Alemow and consequently it had lower photosynthesis rate than control plants. AM fungi play an essential role in citrus rootstock growth and biomass production although the intensity of this response depends on the rootstock salinity tolerance.

Introduction and establishment of apricot in vitro through regeneration of shoots from meristem tips

SummaryIn this study different aspects of the in vitro introduction and establishment of apricot cultivars were investigated through meristem tip culture. The best time to introduce the meristems of ‘Canino’ was when buds were starting to swell. Various plant growth regulators were used at different concentrations on four distinct apricot cultivars to promote the development of the meristems to shoots which could then be micropropagated. Very diverse results were obtained depending on the genotype. In general, meristems did not survive without N6-benzyladenine. Concentrations of gibberellic acid from 2 to 4 mg 1−1 (5.8–11.4 µM) promoted explant elongation. This step was critically important to obtain apricot shoots large enough to be transferred to proliferation medium.