Browsing by Author "Gebauer, Marlene"

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    Adventitious root initiation in adult and juvenile cuttings of Guindilia trinervis, an endemic plant of Chile suitable for biodiesel production
    (2010) Jordan, Miguel; Prehn, Doris; Gebauer, Marlene; Neumann, Jorge; Margot Parada, Gloria; Velozo, Juan; San Martin, Ricardo
    Guindilia trinervis is a native Chilean shrub that bears seeds with a high content of oil suitable for biodiesel production. It was tested for its capacity to form roots in cuttings of juvenile and adult plants in ex vitro as well as in vitro conditions. Variables such as type of cutting, exogenous application of IBA(1) and time of collection were studied. For adult plants, the best ex vitro rooting (79 %) was obtained with distal polynodal cuttings collected in late summer and treated with 100 mg L-1 IBA, but rooting was also achieved in the presence of water alone (up to 69 %). Juvenile plants displayed the best rooting (84 %) with single node cuttings and 50 mg L-1 IBA, as well as in the presence of Seradix (72 %). This treatment also showed the highest number of roots per explant. In vitro rooting of shoot tips took place on modified MS media supplemented with 1.0 mg L-1 IBA yielding roots up to 82 %, compared to nodal sections that rooted scantily. Rooted material could be acclimated and adapted well to greenhouse and nursery conditions. Controls of adult and juvenile cuttings treated with water exhibited spontaneous rooting in most of the treatments. Cuttings from adult plants harvested in late summer rooted better than those harvested in winter. Spring cuttings collected during flowering and fructification did not root. Results indicate that by means of adventitious root initiation G. trinervis can be effectively propagated by distal cuttings, collected in summer or winter. This may allow large-scale production of plant material with desired traits.
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    Descriptive Genomic Analysis and Sequence Genotyping of the Two Papaya Species (Vasconcellea pubescens and Vasconcellea chilensis) Using GBS Tools
    (2022) Carrasco, Basilio; Arevalo, Barbara; Perez-Diaz, Ricardo; Rodriguez-Alvarez, Yohaily; Gebauer, Marlene; Maldonado, Jonathan E.; Garcia-Gonzales, Rolando; Chong-Perez, Borys; Pico-Mendoza, Jose; Meisel, Lee A.; Ming, Ray; Silva, Herman
    A genotyping by sequencing (GBS) approach was used to analyze the organization of genetic diversity in V. pubescens and V. chilensis. GBS identified 4675 and 4451 SNPs/INDELs in two papaya species. The cultivated orchards of V. pubescens exhibited scarce genetic diversity and low but significant genetic differentiation. The neutrality test yielded a negative and significant result, suggesting that V. pubescens suffered a selective sweep or a rapid expansion after a bottleneck during domestication. In contrast, V. chilensis exhibited a high level of genetic diversity. The genetic differentiation among the populations was slight, but it was possible to distinguish the two genetic groups. The neutrality test indicated no evidence that natural selection and genetic drift affect the natural population of V. chilensis. Using the Carica papaya genome as a reference, we identified critical SNPs/INDELs associated with putative genes. Most of the identified genes are related to stress responses (salt and nematode) and vegetative and reproductive development. These results will be helpful for future breeding and conservation programs of the Caricaceae family.
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    Direct and indirect in vitro organogensis of Leucocoryne purpurea (Alliaceae) a chilean ornamental geophyte
    (SEJANI PUBL, 2008) Escobar, Luis H.; Jordan, Miguel; Olate, Eduardo; Barrales, Luis; Gebauer, Marlene
    In vitro shoot induction from callus and direct bulbil formation from shoots were obtained in Leucocoryne purpurea, an endemic vulnerable Chilean species. Basal leaf portions, bulb basal plate and root tips from in vitro gown plants were used as explants. Only bulb basal plate explants displayed morphogenic responses. Callus, shoot and bulbils developed on MS basal medium in the presence of various growth regulator combinations. Callus formation from bulb basal explants ranged between 40 to 100%; the highest response was observed in the presence of 4.5 or 13.6 mu M 2,4-D alone or 4.5 mu M 2,4-D in combination with 0.5 mu M BA after 4 months. Picloram alone or in combination with 2iP or BAP also supported callus initiation. Indirect shoot formation from callus occurred only after a further culture period of 2 months in MS medium containing 0.5 or 2.3 mu M TDZ. Basal bulb plate explants cultured in the presence of TDZ alone (0.5 and 2.3 RM, respectively) exhibited direct shoot formation within 90 days. After subculture in the presence of 0.5 mu M TDZ each single shoot formed new shoots (3 to 4) and new bulbils. However higher TDZ levels, up to 2.3 mu M, produced shoots with roots only, inhibiting bulbil formation, and the 4.5 mu M TDZ concentration caused necrosis.
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    Evaluation of guindilla oil (Guindilia trinervis Gillies ex Hook. et Arn.) for biodiesel production
    (2010) San Martin, Ricardo; de la Cerda, Teofilo; Uribe, Adolfo; Basilio, Paola; Jordan, Miguel; Prehn, Doris; Gebauer, Marlene
    Guindilla plants (Guindilia trinervis Gillies ex Hook. et Arn.) are small shrubs that grow wildly in the mountains of Central Chile in soils and climates not suitable for agriculture. Whole guindilla seeds contain 28-29% w/w oil. Cotyledons represent 45% w/w of the seed and contain 63-64% w/w oil. Main unsaturated fatty acids are oleic (63% w/w), linoleic (8% w/w) and gadoleinic (9.5% w/w), while main saturated fatty acids are palmitic (9.1% w/w) and stearic (3.1% w/w). The content of free fatty acids was 0.06%. Transesterification reactions yielded a biodiesel with ester content > 99%; cetane number 59; oxidative stability at 110 degrees C, 18.9 h; kinematic viscosity at 40 degrees C, 4.867 mm(2)/s; cold filter plugging point, CFPP + 4 degrees C; sulfur content 1.0 mg/kg; sulfated ash < 0.01% p/p; acid value 0.024 mg KOH/g and phosphorous content (< 0.5 mg/kg). All values were within European and US specifications. The relatively high CFPP value limits the use of unblended guindilla biodiesel to high temperature weather locations. The high oxidative stability is probably due to the low content (8.8% w/w) of polyunsaturated acids (e. g. C18:2 + C18:3 + C20:2 + C20:3). Guindilla plants grow wildly with estimated yields of 1000 L oil/ha. Plant improvement programs could make these plants a viable alternative for biodiesel production. (C) 2010 Elsevier Ltd. All rights reserved.
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    Genetic characterization of Japanese plum cultivars (Prunus salicina) using SSR and ISSR molecular markers
    (2012) Carrasco, Basilio; Diaz, Carole; Moya, Mario; Gebauer, Marlene; Garcia-Gonzalez, Rolando
    B. Carrasco, C. Diaz, M. Moya, M. Gebauer and R. Garcia-Gonzalez. 2012. Genetic characterization of Japanese plum cultivars (Prunus salicina) using SSR and ISSR molecular markers. Cien. Inv. Agr. 39(3): 533-543. The genetic characterization of 29 elite Japanese plum cultivars (Prunus salicina) and 4 Prunus cultivars was carried out by analyzing 97 Simple Sequence Repeat (SSR) alleles and 232 binary Inter Simple Sequence Repeat (ISSR) loci. A high level of genetic variability was found for these two molecular markers among the Japanese plum cultivars compared to other Prunus species. On average, the variability found by analyzing the SSR alleles were Na = 12.1, Ne = 5.2, Ho = 0.9, He = 0.8 and F = -0.127, whereas ISSR yielded values of h = 0.15 and I = 0.27. The genetic relationship among cultivars was estimated with Principal Coordinate Analysis (PCA) and a Bayesian clustering approach using the software program Structure. This program identified two subgroups (k=2). The first group included cultivars of four Prunus species: P. salicina, P. armeniaca, P. domestica and P. ceracifera, whose memberships ranged between 0.74 and 1.0. The second group included 19 Japanese plum cultivars and one plumcot cultivar, with memberships between 0.57 and 0.99. With some exceptions, similar relationships among cultivars were foundPCA. The level of genetic differentiation between two groups was low (G(st)=0.055 and phi(ST)=0.04), and a low level of linkage disequilibrium (LD) was observed for all allele combinations. These results suggest that the high level of genetic variability, the low level of LD and the scarce degree of differentiation detected by Structure between the two genetic groups can be explained by the self-incompatibility mechanism that favors the exchange between genetically distant Prunus cultivars and by the intra- and interspecific hybridization strategies frequently used in plum breeding programs.
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    Phenotypic and genetic analysis of a peach and a Japanese plum core collection for pre-breeding and distinctness assessment
    (2022) Carrasco, Basilio; Ramirez, Cesar; Gebauer, Marlene; Meisel, Lee A.; Hasbun, Rodrigo; Silva, Herman
    To know the relationships between phenotypic and genetic variables in a germplasm collection of fruit crops is useful a pre-breeding and cultivar distinctness. A core collection of 23 peaches/nectarines (Prunus persica (L.) Batsch), and 16 Japanese plum (Prunus salicina Lindl. var. salicina) cultivars were evaluated for 33 and 29 characteristics (botanical/ productive) respectively during two growing seasons. Also, eight specific simple sequence repeats (SSRs) markers were analyzed in both species. Principal components analyses revealed seven characteristics (related to the size of the fruit and the firmness of the pulp) as the most important for the 23 peach/nectarine cultivars and four characteristics (yield, fruit size, soluble solids, and harvest time) for the 16 Japanese plum cultivars. These analyses revealed three cultivars of peaches (Diamond Princess, Dixon, and Dr. Davis) and three of nectarines (Ruby diamond, Artic sweet, Summer fire) with the highest values for fruit size and pulp firmness. Four Japanese plum cultivars (Angeleno, Flavor Rich, Red Heart, and Pink Delight) showed the highest values of yield, fruit size, soluble solids, and harvest time. Elite germplasms to carry out a breeding program were identified from both the phenotypic and genetic analysis. Additionally, cultivar-specific SSR alleles were identified and are a relevant tool for cultivar distinctness.
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    Preliminary results of new sweet cherry (Prunus avium) breeding program in Chile
    (INT SOC HORTICULTURAL SCIENCE, 2019) Ayala, Marlene; Gebauer, Marlene; Castro Urrea, Felipe A.; Zoffoli, Juan Pablo
    Chile is the largest sweet cherry producer and exporter of the southern hemisphere. However, most sweet cherry production comes from cultivars originated in other countries. In 2010, the Chilean Export Association, a group of companies and the Pontificia Universidad Catolica de Chile began a traditional sweet cherry breeding program to obtain new cultivars adapted to Chilean growing conditions (e.g., low chill and rainy springs) and long-distance market requirements (e.g., China). The breeding program has focused in expanding the commercial window generating early and late cultivars. Each season around 3,500 and 4,500 hybrids are established in the field with an overall plant propagation efficiency that has ranged between 42.7 and 83.4%. To date, the breeding program has established over 21,000 hybrids on their own roots. Crosses are made either by hand or using cages to enclose whole trees. Hybrids are propagated by either using embryo rescue (40 to 45% hybrids) or seed stratification. Embryo rescue and seed stratification efficiencies have varied between 19.6 and 31.0% and 14.9 and 38.7%, respectively. Seedlings are maintained in greenhouse for about 6 months until establishment in the field. In 2014, first hybrids started bearing fruit and since then more than 600 individuals have been evaluated for yield, fruit quality (i.e., size, firmness, weight, color and SSC) and harvest date, among other characteristics. In 2017, a total of 14 interesting hybrids will be grafted on a dwarfing-precocious rootstock and established in two different locations for pre-commercial evaluations.
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    Resistance to Bensulfuron-Methyl in Water Plantain (Alisma plantago-aquatica) Populations from Chilean Paddy Fields
    (CAMBRIDGE UNIV PRESS, 2008) Figueroa, Rodrioro; Gebauer, Marlene; Fischer, Albert; Kogan, Marcelo
    Bensulfuron-methyl (BSM) has been one of the most widely used herbicides in Chilean rice fields because it controls a wide spectrum of weeds and does not require field drainage for application. However, failures of BSM to control water plantain in rice fields have been noted since 2002. We assessed BSM effects on suspected resistant (CU1 and CU2) and Susceptible (AN I) water plantain accessions collected in Chilean rice fields during 2004 and 2005. BSM rates resulting in 50% growth reduction (GR(50)) of CU2 and CU1 plants were 12- and 33-fold higher than for ANI plants, respectively. Acetolactate synthase (ALS) activity assays in vitro Suggested resistance in CU1 and CU2 was due to an ALS enzyme with reduced BSM sensitivity compared to the AN I biotype. Resistance indices (RI), or ratios of the resistant to susceptible I-50 values (BSM rate to inhibit ALS-enzyme activity by, 50%), were 266 (CU2/AN1) and > 38,462 (CU1/AN1). This agreed with in vivo ALS activity assays where RI were 224 (CU2/AN1) and > 8,533 (CU1/AN1). Resistance levels detected in whole-plant or in vivo ALS activity assays were orders of magnitude lower than those detected in in vitro ALS activity studies suggesting nontarget site mechanisms may have mitigated BSM toxicity. However, a consistent ranking of BSM sensitivity levels (AN1 > CU2 > CU1) throughout all three types of assays suggests resistance is primarily endowed by low target site sensitivity. We conclude that Susceptible and resistant water plantain biotypes coexist in Chilean paddies, and the use of integrated weed management involving herbicides with a different mode of action would be imperative to prevent further evolution of resistance to BSM and possibly cross-resistance to other ALS inhibitors. In vitro ALS-enzyme assays provided the best discrimination of resistance levels between biotypes.
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    Synthetic seed production from somatic embryos of Pinus radiata
    (2008) Aquea, Felipe; Poupin, Maria Josefina; Matus, Jose Tomas; Gebauer, Marlene; Medina, Consuelo; Arce-Johnson, Patricio
    Pinus radiata is one of the most important forestry species in the southern hemisphere. This work describes the regeneration of this plant via somatic embryogenesis from immature zygotic embryos. To improve this process, somatic embryogenic cell suspensions were established in liquid media for the generation of material for embryo maturation. Each developmental stage of these suspensions was characterized by microscopy and their growth phases quantified. An alginate-containing medium was used as an encapsulation method for the somatic embryos that were then germinated as artificial seeds in vitro. The protocols described in this work are both useful and reliable for industrial purposes.