The antifungal protein (AFP) produced by Aspergillus giganteus, encoded by the afp gene, has been used to confer resistance against a broad range of fungal pathogens in several crops. In this research, transgenic olive plants expressing the afp gene under the control of the constitutive promoter CaMV35S were generated and their disease response against two root infecting fungal pathogens, Verticillium dahliae and Rosellinia necatrix, was evaluated. Embryogenic cultures derived from a mature zygotic embryo of cv. ‘Picual’ were used for A. tumefaciens transformation. Five independent transgenic lines were obtained, showing a variable level of afp expression in leaves and roots. None of these transgenic lines showed enhanced resistance to Verticillium wilt. However, some of the lines displayed a degree of incomplete resistance to white root rot caused by R. necatrix compared with disease reaction of non-transformed plants or transgenic plants expressing only the GUS gene. The level of resistance to this pathogen correlated with that of the afp expression in root and leaves. Our results indicate that the afp gene can be useful for enhanced partial resistance to R. necatrix in olive, but this gene does not protect against V. dahliae.
The olive growing is one of the strategic sectors of the Algerian economy. Traditional olive culture located in the mountains of Kabylia offers typical oil widely preferred by a large part of the Algerian consumers. However, this ancestral culture risks not only abandonment but suffers much more from uncontrolled of the good practices surrounding this local product requiring a valorization accompanied by improvement. Indeed, the difficulty to extract the total oil contained in the fruit is one of the main obstacles of the extraction method particularly by pressure. Nevertheless, some actions as the addition of co-adjuvant during the malaxing process allow improving efficiency of the extraction process. Our results indicate that the addition of 2.5% of talc as a co-adjuvant to a moistless paste obtained from whole olives significantly improves the oil yield by about 4.4% without altering the acidity compared to the control. Similarly, stoning improves the moisture of the pressed mass although without improving yield of the oil characterized by a slight decrease in acidity compared to other extracted oils. Therefore, our results confirm the beneficial effect of talc on the extraction of olive oil and contribute to the improvement of the traditional extraction by pressure to enhance the value of this local product.
In vitro plant regeneration via somatic embryogenesis is a powerful tool for rapid, large-scale production of healthy true-to-type plants. This approach is suitable to preserve existing natural genetic variability and propagation of variability generated from genetic improvement programs, including crossing, somaclonal variation, mutagenesis, and somatic hybridization. This chapter outlines a simplified protocol for date palm regeneration via somatic embryogenesis induced in cell suspension cultures. In this protocol, culture medium composition is manipulated, including plant growth regulators and solid (addition of agar) and liquid media to achieve reduction of production cycle of somatic embryogenesis, which increases the multiplication rate of embryogenic callus and improves the quantity and quality of somatic embryos.
<p>Olive improvement by biotechnological tools such as genetic transformation requires an efficient in vitro regeneration system. Somatic embryogenesis seems the most suitable process. Our work describes for the first time the regeneration of whole plants in the main olive cultivar in Algeria ‘Chemlal’ via somatic embryogenesis induced from radicles of mature zygotic embryos. The obtained results showed that the establishment of a competent embryogenic culture is highly influenced by the chemical composition of the calli induction and maintenance media as well as addition of growth regulators. More than 10 and 13 % of nodular calli were obtained after callogenesis respectively on MS and OMc solid media containing IBA and zeatin followed by transfer to the same media without zeatin and a reduced concentration of auxin, while embryogenesis rates of 3.3 and 6.7 % were obtained respectively with IAA on MS medium and NAA on both tested media. However, no embryogenesis was observed with 2, 4-D or control which induced less callogenesis. Subsequently, an ECO medium with IBA, zeatin and BA particularly in liquid culture, allows better calli proliferation and embryogenic expression compared to OM and MS media. Finally, matured somatic embryos germinate quickly on a solid OM basal medium and generate normal well-developed plantlets easily acclimatized to natural conditions.</p>
The in vitro propagation techniques are currently a commercial alternative for the production of plants with good quality in several plant species, including the olive tree (Olea europaea L.). Somatic embryogenesis is the process practically used for the application of several biotechnological tools of improvement and in vitro plant regeneration via the germination of somatic embryos. Our work aims to evaluate the effect of the chemical and hormonal composition of the culture medium on the germination of olive somatic embryos (cv. Chemlal) as well as the micropropagation of the obtained plantlets before their acclimatization to natural conditions. The results indicated that the production of olive plants by somatic embryogenesis depends strongly on the genotype of the somatic embryos (cell line) and more on the culture conditions, particularly the presence of growth regulators. Indeed, a solid OM medium supplemented with hormones (BA and IBA) permitted an advanced root emergence and germination allowing the production of well-developed plants with several leaves. In addition, an OM medium supplemented with Zeatin and IBA allowed better reactivity of micro-cuttings producing well-developed shoots with several emitted roots which facilitates their further acclimatization to natural conditions.
Date palm (Phoenix dactylifera L.) production is severely hampered due to several pests and diseases. Biotechnological tools such as protoplast fusion appear as an alternative to ensure rapid genetic improvement and multiplication of this species. However, establishment of an effective system of plant regeneration from protoplasts culture is a prerequisite for date palm somatic hybridization. In this chapter, we describe an effective protocol to induce microcalli in protoplasts isolated from nodular callus of important Algerian date palm cultivars. In this protocol, the main factors influencing the isolation (i.e., enzymatic solution, mannitol concentration, duration, and mode of maceration) of protoplasts from the calli of Algerian date palm cultivars were optimized. Purified protoplasts were cultured on a semisolid medium supplemented with a hormonal balance of auxin and cytokinin to obtain microcalli formation.
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