Use of Azolla as a growing medium component in the nursery production of olive trees

Peat is used in olive-tree nurseries as a component in commercial growing media. Environmental and economic pressures are questioning the use of peat as a component of substrates. In order to remain competitive and to satisfy environmental concerns, it is necessary to identify and evaluate possible alternatives to peat. This study involves the use of Azolla filiculoides, as a growing media component in olive nurseries (Olea europaea L.) for containerized plants. Four treatments were established, based on the addition of increasing quantities of Azolla (0%, 25%, 50%, and 100 %). Were determined some physical and chemical properties of media, the growth, the physiological parameters and nutritional state of olive plants. The physical and chemical properties of the media were significantly affected by the Azolla content. Nursery-produced olive plants grown in substrates supplemented by 50 % Azolla displayed linear growth and the total biomass production greater than those of the control medium. The research indicated that Azolla might be suitable substrate component for olive plants grown in containers

Chlorophyll fluorescence quenching as a tool to screen olive cultivars tolerant to drought stress

The measurements of fluorescence chlorophyll is considered a promising technique to rapidly quantify the response to physiological stress in higher plants. Drought stress can be considered one of the most frequent environmental constraints causing the failure of newly planted trees. Olive tree (Olea europaea), a representative drought stress tolerant plant, is one of the most typical and economically relevant plant species grown in the Mediterranean area. However, as different cultivars may exhibit different drought tolerance level, the selection of the most drought tolerant cultivars acquires relevance. The objective of this study was to determine whether information obtained with chlorophyll fluorescence measurements carried out on detached olive leaves subjected to dehydration in vitro, may be translated on the whole olive plant. Results revealed that in vitro measurements were effective to evidence strong differences in the Fv/Fm ratio decline among the cultivars, following 24 hours of dehydration, and it was possible to distinguish different level of putative tolerances. Measurements carried out on whole plants of different cultivars confirmed, indeed, the results obtained in vitro. The results indicated that the chlorophyll fluorescence measurement represents a valid technique for a rapid screening of olive cultivars tolerance to drought stress

Olive Germplasm: Varieties, Descriptor List and Molecular Markers

The olive tree is of strategic importance for the Mediterranean basin, and olive oil is an important component of Mediterranean diet, with beneficial properties for human health. The longevity of this species and the low breeding pressure have largely determined the genetic diversity that exists in the olive tree. Today, olive resources are represented by very wide germplasm estimated in more than 1.700 cultivars. This chapter is a report on the synthesis of what is known about the botanical and historical origin of olive tree. Furthermore, the morphological and genetic methodologies used to identify olive cultivar are examined

Polymorphisms of Seed Storage Proteins in Olea europaea L. Cultivars

The use of Olea europaea globulins as genetic markers for the identification of the cultivars was perfomed in the laboratory of Genetics of Department of Agriculture, Food and Environment, University of Pisa. The major component of Olea europaea L. seed storage proteins is represented by globulins. These fractions were characterised by electrophoresis and compared with the proteins extracted from protein bodies. The biochemical analysis of the olive seed globulins was carried out in sixteen different cultivars coming from several geographical areas of Italy. The electrophoretic patterns in polyacrylamide gels electrophoresis in denaturing conditions (SDS-PAGE) evidenced both qualitative and quantitative differences. It was possible to identify all the cultivars by             their electrophoretic spectra. Number and position of the electrophoretic bands allowed the construction of a similarity matrix and of a dendrogram that allowed the separation into groups, according to their phylogenetic relationships. The several clusters seem to be related with agronomic traits such as fruit size or oil production; no relationships were found with the geographical cultivation areas

Identification and characterization of Italian common figs (Ficus carica) using nuclear microsatellite markers

Common fig (Ficus carica L.) is one of the most ancient domesticated species, originated, supposedly in Arabia, from where it diffused to the Middle East and Asia, and to the Mediterranean basin, where it greatly diffused. More than 600 fig varieties have been described, but it is conceivable that this number is underestimated. Along all the Italian territory, there is a rich germplasm of fig composed of a large number of varieties (approximately 300) of very not well defined origin. Effectively, during several centuries of cultivation and propagation by seed, a large number of genotypes appeared and were selected, leading to the generation of an uncountable number of genotypes, different in numerous traits, particularly in those related to leaves and fruits features. Unfortunately, the extensive existing fig genetic patrimony is facing genetic erosion; for this reason, it is extremely important to study and valorised it, in order to preserve the remaining biodiversity. The purpose of this study was to genetically characterize, with nSSR markers, 79 fig accessions, collected in several areas in Italy. The set of chosen markers resulted highly polymorphic, and allowed the characterization of all the studied accessions. Data were analysed by cluster analysis, and the results demonstrated a great genetic variability within the population. The nSSR used, moreover, allowed us to identify all accessions and to recognised possible homonyms and synonyms, and cases of intravarietal clones

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Modulated gene expression during the cold acclimation process in tolerant and sensitive clones of cultivar Leccino (Olea europaea L.)

The plants are constantly exposed to environmental changes that need to be addressed with appropriate modifications of gene expression. The genetic approach to the study of the response to biotic and abiotic stresses is of great importance in plants, for the identification of the genes involved and their activation mechanisms. In our work, we have characterized the expression of some genes induced during the acclimation under low temperatures in plants of 'Olea europaea' L., by isolating DNA sequences differentially expressed in a cold tolerant clone of Leccino cultivar by using the suppression subtractive hybridisation (SSH). The sequences obtained were analysed by sequencing. Some sequences of the libraries and from orthologous genes expressed in various abiotic/biotic stress treatments, were labelled and used as probes for slot blot hybridization with total RNAs extracted from cold sensitive and tolerant Leccino clones treated with decreasing temperatures down to -10 degreesC, thus mimicking a process of cold acclimation. Six genes were found to be of interest for the adaptation to cold stress, whose expression is differentially modulated in the two clones. The most important result was in a bimodal response during the acclimation phases, the causes of which have been discussed

Two Advanced Cryogenic Procedures for Improving <i>Stevia rebaudiana</i> (Bertoni) Cryopreservation

Cryopreservation is a useful tool for the long-term storage of plant genetic resources, and different cryogenic procedures have recently been developed. The present study focused on the use of the Droplet-vitrification (DV) and V cryo-plate protocol for the cryopreservation of Stevia rebaudiana in vitro-derived apical shoot tips and axillary shoot tips. A preliminary test showed that 90 and 120 min PVS2 (Plant Vitrification Solution 2) treatment significantly reduced the regrowth of the explants before immersion in liquid nitrogen (LN). For both procedures tested, the best osmoprotective condition for obtaining a higher regrowth of cryopreserved explants occurred when explants were PVS2 treated for 60 min. After direct immersion in LN, thawing and plating, the highest regrowth recorded was 80% with DV and 93% with V cryo-plate. Moreover, shoot tips proved to be a more suitable material for Stevia cryopreservation. A satisfactory vegetative regrowth was observed in the subcultures following cryopreservation by DV and V cryo-plate cryogenic procedures

Two Advanced Cryogenic Procedures for Improving Stevia rebaudiana (Bertoni) Cryopreservation

Cryopreservation is a useful tool for the long-term storage of plant genetic resources, and different cryogenic procedures have recently been developed. The present study focused on the use of the Droplet-vitrification (DV) and V cryo-plate protocol for the cryopreservation of Stevia rebaudiana in vitro-derived apical shoot tips and axillary shoot tips. A preliminary test showed that 90 and 120 min PVS2 (Plant Vitrification Solution 2) treatment significantly reduced the regrowth of the explants before immersion in liquid nitrogen (LN). For both procedures tested, the best osmoprotective condition for obtaining a higher regrowth of cryopreserved explants occurred when explants were PVS2 treated for 60 min. After direct immersion in LN, thawing and plating, the highest regrowth recorded was 80% with DV and 93% with V cryo-plate. Moreover, shoot tips proved to be a more suitable material for Stevia cryopreservation. A satisfactory vegetative regrowth was observed in the subcultures following cryopreservation by DV and V cryo-plate cryogenic procedures