Regeneration of Algerian

Stigma/style somatic embryogenesis is one of the efficient methods in plant regeneration of most Citrus ssp., without inducing somaclonal variations. Furthermore, somatic embryogenesis from style/stigma proved to be effective in the elimination of the main citrus virus and virus-like diseases. This technique was applied on Algerian citrus collection. Different Citrus species [Citrus sinensis (L.) Osbeck, C. limon (L.) Burm, C. reticulata Blanco, C. paradisi Macfad, C. reshni Hort. ex Tan., C. jambhiri Lush and C. maxima (Burm.) Merrill] were chosen and tested for the presence of the main virus and virus-like agents. Most of the genotypes showed to be infected, mainly by viroid agents. Closed flowers were collected and in vitro cultured on a Murashige and Skoog (MS) medium supplemented with 6- benzylaminopurine. All explants produced callus about 4 to 9 days after culture initiation, whereas embryogenesis occurred after 38 to 150 days in most of the cultured genotypes. Formed embryos were cultured in a single tube before in vivo acclimatization. After sanitary assays, regenerated plants were shown to be free from the agents detected in the mother trees.Key words: Algeria, citrus germplasm, plant regeneration, sanitation, somatic embryogenesis

A review of elliptical and disc galaxy structure, and modern scaling laws

A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their models to describe the radial distribution of stars in `nebulae'. This article reviews the progress since then, providing both an historical perspective and a contemporary review of the stellar structure of bulges, discs and elliptical galaxies. The quantification of galaxy nuclei, such as central mass deficits and excess nuclear light, plus the structure of dark matter halos and cD galaxy envelopes, are discussed. Issues pertaining to spiral galaxies including dust, bulge-to-disc ratios, bulgeless galaxies, bars and the identification of pseudobulges are also reviewed. An array of modern scaling relations involving sizes, luminosities, surface brightnesses and stellar concentrations are presented, many of which are shown to be curved. These 'redshift zero' relations not only quantify the behavior and nature of galaxies in the Universe today, but are the modern benchmark for evolutionary studies of galaxies, whether based on observations, N-body-simulations or semi-analytical modelling. For example, it is shown that some of the recently discovered compact elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to appear in "Planets, Stars and Stellar Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references incl. many somewhat forgotten, pioneer papers. Original submission to Springer: 07-June-201

COMPARING INSECTICIDES AND DISTRIBUTION TECHNIQUES AGAINST RED PALM WEEVIL

The Red Palm Weevil (RPW), Rhynchophorus ferrugineus (Olivier, 1790) is the major pest for both amenity and economic palms all over the world. RPW inflicts severe economic losses and several techniques have been proposed to lower its population below the economic threshold. Chemical control on healthy (symptomless) palms are the only suitable approach to control RPW infesting Phoenix canariensis because of its preventive and protective actions (2P). Different techniques permit to distribute insecticides. Six different active ingredients were tested: Imidacloprid, Thiametoxam, Dimethoate and Abamectin by tree injection, and Clothianidin and Azadirachtin through tree injection and soil application. The research was performed over a total of 111 Phoenix palms, namely eighty-nine P. canariensis plus twenty-two P. dactylifera in different countries (Italy, Malta and Syria). Treatments were carried out in homogeneous plots testing different insecticides and distribution techniques in order to evaluate distinctive protective and preventive effects for each active ingredient. We compared uptake dynamics, side effects and effectiveness along with the fallouts of phytosanitary treatments in urban centres and commercial palm plantations, insecticide phytotoxicity, cost effectiveness of the different distribution methods

Evaluation of some growth regulator effects on encapsulated in vitro-derived microcuttings of three Italian Ficus carica L. genotypes.

In this study, the encapsulation technology based on the calcium alginate coating was applied to some Ficus carica L. genotypes. Uninodal microcuttings (3-4 mm long), excised from in vitro proliferating shoots of three Italian cultivars (‘Bifera’, ‘Palazzo’ and ‘Catalanisca’), were employed. The influence of three different plant growth regulators (PGRs): 6-benzylaminopurine (BAP), meta-topolin (MT) and zeatine (ZEA), added to the artificial endosperm, were evaluated. Particularly, the viability, regrowth and conversion parameters of the synthetic seeds were registered after 60 days from the sowing on a hormone-free medium. Results showed that the cultivars ‘Catalanisca’ and ‘Palazzo’ showed the highest viability average rate (90%), followed by ‘Bifera’ (80%). Encapsulated microcuttings regrowth percentage was highest for ‘Palazzo’ (86.7%), followed by ‘Catalanisca’ (81.7%) and ‘Bifera’ (66.7%), while the conversion rate was comparable for the three cultivars (43.4, 40.0 and 48.3%, respectively). A strong interaction between cultivars and PGRs was observed. Moreover, regarding the effect of the PGRs, BAP and MT provided the best results about regrowth and conversion, even if the cultivar ‘Catalanisca’ presented 100% of regrowth with ZEA. To our knowledge, this is the first time, that encapsulation technology has been applied to Italian cultivars of Ficus carica

Elimination of Citrus variegation virus (CVV) by seed cryotherapy

Citrus variegation ilarvirus (CVV) is one of the oldest viruses reported in Citrus, which produces crinkling, puckering and variegation of leaves in field trees and, occasionally, variegated and deformed fruits. This virus is primarily transmitted by grafting. However, no consistent data are available concerning CVV seed transmission, which is apparently low. The elimination of CVV in citrus genotypes is carried out by shoot-tip-grafting. In the case of seed sources, virus elimination directly in the seeds becomes essential. In cryotherapy, plant pathogens such as viruses, phytoplasmas and bacteria are eradicated by exposing explants to liquid nitrogen. It allows treatment of a high number of samples and results in a high frequency of pathogen-free regenerants. In this work, three polyembryonic Citrus genotypes (sour orange, mandarin and lemon), which were found infected by CVV, were used for trials of virus seed transmission and CVV elimination by dehydration/cryopreservation of the seeds. The dehydrated seeds were placed in cryovials which were then plunged into liquid nitrogen at -196°C. ISSR markers were used to discriminate between zygotic and nucellar plants after treatment. TAS-ELISA and RT-PCR were applied for CVV detection in the seed components before cryopreservation and in the produced seedlings after treatment. CVV seed transmission was assessed for the first time in sour orange and lemon genotypes by serological and molecular means. All tested Citrus genotypes showed CVV infection in both components of the seed plunged in liquid nitrogen. However, all plantlets developed from cryopreserved seeds were CVV-free 2 years after transplanting