Browsing by Author "Serrano, C"

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    Expression of the chicken lysozyme gene in potato enhances resistance to infection by Erwinia carotovora subsp, Atroseptica
    (2000) Serrano, C; Arce-Johnson, P; Torres, H; Gebauer, M; Gutierrez, M; Moreno, M; Jordana, X; Venegas, A; Kalazich, J; Holuigue, L
    Infection of potato plants and tubers with the bacterium Erwinia carotovora subsp, atroseptica produces blackleg and soft rot diseases, which cause significant losses to crops and stored potatoes. In order to obtain resistance against this bacterium, the gene chly encoding the enzyme lysozyme from chicken was introduced into potato plants (cv. Desiree) via Agrobacterium-mediated transformation. Sixty-three and 69 transgenic potato clones were evaluated in the greenhouse for resistance to blackleg and soft rot diseases, respectively. Results reported in this paper indicate that 21%-29% of the potato clones showed increased resistance to infection by the bacterium E. c, subsp, atroseptica T7, as revealed by a reduced severity of blackleg or soft rot symptoms. Nine clones showing different levels of resistance were selected for further molecular analysis. The number of copies of the transgene integrated in the plant genome of these clones was estimated by Southern blot analysis. The level of transgene expression, detected by Northern blot analysis, correlated with the level of resistance detected in these clones.
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    Regeneration of whole plants from apical meristems of Pinus radiata
    (2003) Prehn, D; Serrano, C; Mercado, A; Stange, C; Barrales, L; Arce-Johnson, P
    A methodology to regenerate whole plants of Pinus radiata from apical meristems of 3- and 7-year-old trees was developed. Meristematic domes with two or three leaf primordia were excised from surface-sterilized branch tips of field-grown plants and cultured in LP medium with half strength macronutrients (1/2 LP) and full strength micronutrients. The early growth of meristems required approximately 12 weeks, including a recovery stage during the first 2 weeks. After 8 weeks, some meristems developed abnormal phenotypes and died during the subsequent stages of development. However, healthy meristems elongated and formed shoots when they were transferred to LP medium supplemented with MS vitamins, 30 mg l(-1) casein hydrolysate, and 0.4 g l(-1) agar plus 2.85 g l(-1) Gelrite. Meristems that developed vigorous shoots were used for rooting experiments when they were 2 cm in length. Whole plants were obtained after 5 days of root induction in water-agar medium containing 8.2 muM IBA and 5.4 muM NAA and 1 month culture in LP medium with 10 g l(-1) sucrose. Plants regenerated from meristems were further propagated by rooting of cuttings. Of the rooted cuttings, 10% were morphologically juvenile.
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    Replicase mediated resistance against Potato Leafroll Virus in potato Desiree plants
    (2004) Ehrenfeld, N; Romano, E; Serrano, C; Arce-Johnson, P
    Potato leafroll virus (PLRV) is a major menace for the potato production all Over the world. PLRV is transmitted by aphids, and until now, the only strategy available to control this pest has been to use large amounts of insecticides. Transgenic approaches involving the expression of viral replicases are being developed to provide protection for plants against viral diseases. The purpose of this study was to compare the protection afforded by the differential expression of PLRV replicase transgene in potato plants cv. Desiree. Plants were genetically modified to express the complete sense PLRV replicase gene. Two constructions were used. one containing the constitutive 35SCaMV promoter and the other the phloem-specific RolA promoter from Agrobacterium rhizogenes. Transgenic plants were infected with PLRV in vitro, using infested aphids. In plants in which 35SCaMV controlled the expression of the PLRV replicase gene, signs of infection were initially detected. although most plants later developed a recovery phenotype showing undetectable virus levels 40 days after infection. In turn, those plants with the RolA promoter displayed an initial resistance that was later overcome. Different molecular mechanisms are likely to participate in the response to PLRV infection of these two types of transgenic plants.