Crops In Chile Research Articles

Potential repellent activity of the essential oil of ruta chalepensis (linnaeus) from chile against aegorhinus superciliosus (guérin) (Coleoptera: Curculionidae)

The objective of this study was to evaluate the repellent effect of the essential oil of the rue (Ruta chalepensis) against the weevil Aegorhinus superciliosus, an important pest of fruit crops in Chile. Rue essential oil was obtained by steam distillation, and its components were identified by GC-MS. Their effect on adult A. superciliosus insects was evaluated using four-arm olfactometric bioassays. The extraction process had a yield of 0.3% on a dry weight basis, and a chromatographic analysis showed the presence of nine compounds, which represented 89.3% of the total components. The major compounds were 2-nonanone (41.7%) and 2-undecanone (40.1%). Behavioral bioassays showed that the rue essential oil elicited a repellent effect against male and female A. superciliosus (p ≤ 0.05) at a concentration of 1.92 x 10 7 ng/cm 2 . However, at a lower concentration of the oil (285.7 ng/cm 2 ), only females were repelled (p ≤ 0.05). The repellency observed against A. superciliosus could be attributed to high concentrations of both ketones, suggesting that rue essential oil can be considered as a potential repellent that could reduce the infestation of this weevil. The role of the compounds identified and the repellent activity of this evergreen shrub are discussed.

Anthocyanin characterization, total phenolic quantification and antioxidant features of some Chilean edible berry extracts.

The anthocyanin composition and HPLC fingerprints of six small berries endemic of the VIII region of Chile were investigated using high resolution mass analysis for the first time (HR-ToF-ESI-MS). The antioxidant features of the six endemic species were compared, including a variety of blueberries which is one of the most commercially significant berry crops in Chile. The anthocyanin fingerprints obtained for the fruits were compared and correlated with the antioxidant features measured by the bleaching of the DPPH radical, the ferric reducing antioxidant power (FRAP), the superoxide anion scavenging activity assay (SA), and total content of phenolics, flavonoids and anthocyanins measured by spectroscopic methods. Thirty one anthocyanins were identified, and the major ones were quantified by HPLC-DAD, mostly branched 3-O-glycosides of delphinidin, cyanidin, petunidin, peonidin and malvidin. Three phenolic acids (feruloylquinic acid, chlorogenic acid, and neochlorogenic acid) and five flavonols (hyperoside, isoquercitrin, quercetin, rutin, myricetin and isorhamnetin) were also identified. Calafate fruits showed the highest antioxidant activity (2.33 ± 0.21 μg/mL in the DPPH assay), followed by blueberry (3.32 ± 0.18 μg/mL), and arrayán (5.88 ± 0.21), respectively.

First Report of Crown Rot of Strawberry Caused by Macrophomina phaseolina in Chile.

In recent years, an increase of collapsed and dead strawberry plants has been observed in several fields in central Chile, specifically in San Pedro, Melipilla, an important area for strawberry cultivation in the country. To determine the causal agent of the disease and the extent of the problem, 25 sample sites of 1 ha each, distributed in different San Pedro zones, were surveyed at the end of the 2011 season (from December 2010 to February 2011). Cross sections of the crowns of symptomatic strawberry plants showed necrotic tissue and brown-red to dark brown areas on the vascular ring. Samples of the affected crowns were superficially disinfested and plated on potato dextrose agar with 200 μg/ml of streptomycin sulfate. Dark gray colonies were observed after 7 days of incubation at 24°C. Pure cultures of the pathogen showed aerial mycelium and abundant dark oblong sclerotia. Fifty sclerotia were measured, averaging 120 × 74 μm. Twenty-one isolates were identified molecularly utilizing the species specific primers MpKFI and MpKRI (2) that yielded a 350-bp fragment. The amplified DNA fragments were sequenced and BLAST analysis showed a 99% nucleotide sequence identity with Macrophomina phaseolina (GeneBank Accession No JX535007.1). Both morphological and molecular analyses confirmed that the isolated species corresponded to M. phaseolina, causal agent of crown and root rot in strawberry. Four representative isolates were selected to conduct pathogenicity tests. Inoculum was prepared by incubating the pathogen for 28 days at 20°C in sterilized oat seeds. Pots of 1.5 liters were filled with a mixed substrate of peat and perlite (2:1), amended with inoculated oats at 9 g per liter of substrate. 'Camarosa' strawberry plants were planted and grown in a glasshouse for 1 month. Six replicated plants per isolate and six plants growing on non-inoculated substrate were left as controls. Ninety-five percent of the inoculated plants showed wilt and collapse symptoms 22 days after transplant, whereas no symptoms were observed in the control plants. M. phaseolina was reisolated from the crowns of symptomatic plants, fulfilling Koch's postulates. The pathogen was isolated from symptomatic strawberry plants in 14 of the 25 sampled sites. Although M. phaseolina was described previously on other crops in Chile, to our knowledge, this is the first report of M. phaseolina causing crown rot of strawberry. The disease has been recently reported in Spain, the United States, and Argentina (1,3,4).

Diaporthe ambigua Associated with Post-Harvest Fruit Rot of Kiwifruit in Chile.

Kiwifruit is an important, expanding commercial crop in Chile. Several fungi have been reported to be associated with post-harvest rots of kiwifruit worldwide (2). During 2011 and 2012, kiwifruit produced in the VI and VII regions of Chile, showing symptoms of inner rot, were investigated with the aim of identifying the disease agent. The affected fruits had brown pubescent skin at the stem end that became soft and lighter in color than the adjacent firm healthy tissues. A watery exudate and white to pale grayish mycelial mats frequently developed at the stem end of the fruit, causing a water-drop stain down the sides on the dry brown healthy skin. The underlying tissue accessed by peeling off the skin was usually water soaked, soft, and lighter green than the healthy tissue. A fermented sour odor occurred frequently on severely decayed fruits. After incubation at 25°C over 7 days on potato dextrose agar (PDA), white to grayish, pale aerial mycelial mats were recovered from fragments of symptomatic kiwifruit superficially disinfected with 95% ethanol. After 2 weeks, black, spherical pycnidia developed, bearing hyaline, ellipsoidal, biguttulate conidia (5.4 to 12.6 × 2.1 to 4.7 μm). After 3 weeks, abundant perithecia embedded in a distinct, black, elevated stroma developed. Perithecia were black, globose, 200 to 500 μm in diameter with necks sinuous, filiform, 550 to 840 × 50 to 95 μm. Clavate, sessile asci, 30.9 to 50.2 × 6.6 to 12.5 μm contained ascospores biseriate, hyaline, smooth, fusoid-ellipsoid, widest just above the septum, tapering towards both ends, medianly septate, constricted at the septum at maturity, with 1 to 2 guttules per cell ascospores, 5.9 to 9.7 × 2.5 to 4.3 μm. All colonies obtained from kiwifruit displayed the same morphological traits and were consistent with those of a Diaporthe sp. (1). The internal transcribed spacer (ITS) region was sequenced using ITS1/ITS4 primers (4). Analysis of ITS region of kiwifruit isolates Damb_12 and Damb_16 (GenBank Accession Nos. KC294545 and KC294544, respectively) revealed 100% nucleotide identity to Diaporthe ambigua (HM575420, HM575419, DQ286274, DQ286270, and DQ286271). Six millimeter plugs from fungal colonies growing on PDA at 25°C for 7 days were used to inoculate 15 healthy untreated, ripe 'Hayward' kiwifruits. Control fruits were inoculated with agar plugs. Inoculated fruits were incubated at 25°C and 80% relative humidity. After 7 days, white to pale grayish mycelial mats developed only on the inoculated fruits, releasing a water drop stain. The underlying tissue was lighter green and water soaked. D. ambigua was reisolated only from the inoculated fruits. D. actinidiae has been previously reported on kiwifruit canes in Chile (3); however, to our knowledge, this is the first report on the occurrence of D. ambigua (Phomopsis ambigua) on kiwifruit in Chile. The fungal isolates (no. 1 to 21) have been deposited in the Laboratorio de Fitopatología Frutal y Molecular, Departamento de Sanidad Vegetal, Facultad de Ciencias Agronómicas de la Universidad de Chile.

Cisgenesis and Intragenesis: New tools For Improving Crops

Genetically Modified Organisms (GMO) could be the answer for many relevant problems affecting crops. However, improving crops through GMO is also often associated with safety concerns, environmental risks and health issues due to the presence of foreign DNA. These limitations have prompted the development of alternative technologies. Recently, cisgenesis and intragenesis have been developed as new tools aimed to modify crops. While cisgenesis involves genetic modification using a complete copy of natural genes with their regulatory elements that belong exclusively to sexually compatible plants, intragenesis refers to the transference of new combinations of genes and regulatory sequences belonging to that particular species. So far, application of cisgenesis and intragenesis as alternatives to conventional transgenesis are limited to a few species, mainly due to the lack of knowledge of the regulatory sequences required. The grape is one of the most cultivated crops worldwide and is the most economically relevant crop in Chile. Its genomic sequence has been completed, making available new sources of information to improve grape traits by genetic manipulation. This review is focused on the current alternatives to transgenesis in plants, including new approaches to develop marker-free crops, their application to economically relevant crops and future perspectives in the area. Also, the identification of grapevine promoters with a wide range of expression profiles is shown. The expression pattern of these genes was analyzed in different tissues and developmental stages, as well as under several stresses and stimuli, giving a broad range of expression patterns, including genes expressed exclusively during ripening, in response to sugars, senescence and biotic stress, among others. Genes with strong and constitutive expression were also identified. Functional analysis using reporter genes has been conducted in order to confirm the promoter's transcription activity, opening new possibilities for developing cisgenic/intragenic grapevines.

First Report of Shoot Blight and Canker Caused by Diplodia coryli in Hazelnut Trees in Chile.

Shoot blight, twig and branch cankers with grayish discoloration, roughened tissue, and dieback were observed in 5-year-old European hazelnut trees (Corylus avellana L.) cv. Barcelona at two commercial plantations in the Allipén locality, Region de La Araucanía (38° 59' 24.76″ S, 72° 29' 35.58″ W), Chile, during the 2011 to 2012 growing season. In addition, discoloration of the wood was observed in cross-sections. In order to isolate the causal agent, entire twigs and shoot fragments with cankers were sterilized in 0.5% sodium hypochlorite for 2 minutes, followed by two rinses with sterile distilled water. The tissues were then stored in a humid chamber. Sub-epidermal black pycnidia with sporulation were detected on the symptomatic tissue. Conidia were transferred to potato dextrose agar (PDA) (Difco, Lawrence, KS) and incubated at 25°C in the dark. The mycelia were black, creeping, and compact in appearance. The mature conidia were dark brown with a single septum, slightly constricted at the septum, and ovoid with a broadly rounded apex; some had a truncated base. Conidia had the following measurements: (20.0-) 23.1 ± 1.9 (-28.0) × (10-) 11.9 ± 1.2 (-15) μm with an average length/width ratio of 1.95 ± 0.17 (n = 50). These morphometric characteristics correspond to those of Diplodia coryli Fuckel (1870), teleomorph: Botryosphaeria sensu lato. The identity of the fungus was confirmed using internal transcribed spacer (ITS) rDNA sequencing completed at CABI, United Kingdom. The sequencing report indicated that the isolate (IMI-501235a) had 100% homology with a reference strain (CBS 242.51) in the CBS collection. The obtained sequence was deposited in GenBank (Accession No. JX163116). The anamorphs of Botryosphaeria have been divided into up to 18 genera (1), many of which are not clearly defined. Diplodia (3), including D. coryli (CBS 242.51) and D. juglandis (CBS 188.87), have been included within the genus Dothiorella (2), but the taxon names have not been formally changed. A pathogenicity test was conducted with one isolate (IMI-501235a) and four 1-year-old plants of hazelnut cultivar Barcelona. Plants were maintained in individual bags in greenhouse conditions (14/10 hours dark/light, 20°C; 70% RH). Prior to inoculation, plant tissues were externally disinfected with sodium hypochlorite (2%) and rinsed with sterile distilled water. Each plant was inoculated at fresh wound sites on two shoots and three twigs around each vegetative bud. The inoculum consisted of an agar plug with mycelia (5 mm) from the margin of an actively growing colony cultured on PDA media for 7 days. Each wound was covered with moistened cotton and sealed with Parafilm; a control plant was inoculated in the same way with agar only. After 3 months, fragments of necrotic and discolored vascular system tissues from inoculated shoots were removed and incubated on PDA. D. coryli was consistently recovered from these tissues, satisfying Koch's postulates. The control plant showed no symptoms of the disease. D. coryli has been reported to cause symptoms of dieback (dead branches) in Italy and Spain. To our knowledge, this is the first report of D. coryli on C. avellana cv. Barcelona in Chile. European hazelnut is an emerging crop in Chile, grown mainly for export, and management strategies for this disease will need to be developed.

First Report of Root Rot of Chicory Caused by Phytophthora cryptogea in Chile.

Chicory (Cichorium intybus L. var sativum Bisch.), a relatively new high-value crop in Chile, was introduced for commercial production of inulin. Inulins are polysaccharides extracted from chicory tap roots that are used in processed foods because of their beneficial gastrointestinal properties. Approximately 3,000 ha of chicory are grown for local processing in the BioBio Region near Chillan in south central Chile. Recently, a severe rot of 1 to 3% of mature roots in the field and after harvest has been observed in most fields, which caused yield and quality losses. Typical symptoms include a brown discoloration and a soft, watery decay of the root. Tissue pieces from symptomatic roots were placed on water agar and clarified V8 juice agar medium amended with antibiotics (1) for isolation of the causal pathogen. A Phytopthora sp. had been consistently isolated from root lesions, and axenic cultures were obtained using single-hypha transfers. The species was provisionally identified as Phytopthora cryptogea (Pethybridge and Lafferty, 1919) on the basis of morphological and cultural characteristics (1). Mycelia grew between 5 and 30°C with optimal growth at 20 to 25°C and no growth at 35°C. All isolates produced hyphal swellings and nonpapillate, persistent, internally proliferating, and ovoid to obpyriform sporangia with mean dimensions of 45 × 31 μm in sterile soil extract. The isolates were of A1 mating type because they produced oospores only when paired with reference isolates of P. cinnamomi A2 on clarified V8 juice agar amended with thiamine, tryptophan, and β-sitosterol (1) after 20 days at 20°C in the dark. On the basis of morphological and sequence data from cytochrome c oxidase subunit 1 and 2, internal transcribed spacer 2, and β-tubulin (GenBank Accession Nos. JQ037796 to JQ037798, respectively), the pathogen was identified as P. cryptogea. Pathogenicity tests were conducted using three isolates of P. cryptogea by placing a 7-mm-diameter disk from a 1-week-old V8 agar culture on 10 wounded and nonwounded healthy chicory roots (2). Control roots were mock inoculated with agar plugs. The inoculated roots were incubated at 20°C in a moist chamber. Root rot symptoms, identical to those observed both in field and storage, developed after 4 to 6 days only on wounded sites inoculated with the pathogen, and P. cryptogea was reisolated from these inoculated plants. Mock-inoculated roots remained healthy. This experiment was completed twice and similar results were obtained. To our knowledge, this is the first report of Phytophthora root rot of chicory caused by P. cryptogea in Chile.

Environmental impacts and energy demand of rapeseed as an energy crop in Chile under different fertilization and tillage practices

Abstract The implementation of energy crops in Chile is an option that requires prior environmental studies within the framework of a sustainable national policy of energy security. The aim of this study is to assess the environmental performance of rapeseed crop ( Brassica napus L.) in Chile in view of its potential use for the production of biodiesel. Using Life Cycle Assessment (LCA), the study quantifies the energy demand and the environmental impacts associated with the main tillage systems of Chilean rapeseed production on a national level: conventional tillage and zero tillage, and with four mineral fertilisation trials on a local level (combination of N, P and K rates). In the inventory, the agricultural inputs are obtained from national sources; international databases processes are partially adapted to Chilean conditions. For the impact assessment, the CML 2 baseline 2001 method is applied. The results indicate that the two tillage systems present similar energy demand and environmental impacts profile, with the exception of the categories photochemical ozone creation and freshwater aquatic ecotoxicity. In both systems, the use of mineral fertilisers has the greatest energy demand, with a contribution of over 75%, and the greatest environmental impacts. In contrast, fungicides and seeds have a minimum contribution, all together, less than 3%. The results of LCA of fertilisation trials show that higher fertilisation rates require an increase in seed yield to compensate additional impacts and to be environmentally favourable.

Effect of prey density on intraguild interactions among foliar- and ground-foraging predators of aphids associated with alfalfa crops in Chile: a laboratory assessment

Among the aphidophaga guild present in alfalfa [Medicago sativa L. (Fabaceae)], coccinellids forage on aphids most of the time on the foliage and carabids on the ground. The result of their combined effect can be synergistic, additive, or antagonistic, but this may depend on the prey density and interacting predatory species. In this study, we first determined, under laboratory conditions, the relative tendencies of Therioaphis trifolii (Monell), Acyrthosiphon pisum (Harris), and Aphis craccivora Koch (all Hemiptera: Aphididae) to drop in the presence and absence of two predators: Eriopis connexa (Germ) and Hippodamia variegata (Goeze) (both Coleoptera: Coccinellidae). These experiments showed that T. trifolii and A. pisum dropped more frequently than A. craccivora, and dropping was more frequent in the presence of H. variegata. We also determined the functional responses to aphid densities of five beetle species (Coleoptera: Carabidae) commonly found in alfalfa fields in Chile. All carabid species consumed aphids, with Trirammatus aerea (Dejean) being one of the most voracious. Then, we tested the hypothesis that the interactions between both coccinellid species and T. aerea would be antagonistic at low prey densities, because of competition or intraguild predation, and synergistic as prey density increases. For this, we recorded aphid consumption when predators were alone, or in combinations of a foliar and a ground predator, for five prey densities. For all predators and combinations, aphid consumption increased continuously with aphid density, and more prey were eaten when a foliar- and a ground-foraging predator were combined than when either predator was present. But, contrary to our expectations, we found that the interaction of these foliar- and ground-foraging predators was additive for all prey densities. Our results suggest that coexistence of these species would not interfere with aphid biological control in alfalfa.

EPIDEMIOLOGY AND CONTROL OF SOME DISEASES AFFECTING PROTEACEAE CROPS IN CHILE

Since the introduction of Proteaceae crops in Chile, there have been at least seven diseases described caused by fungi (Phytophthora, Fusarium, Alternaria, Botrytis, and Cladosporium) and bacteria (Pseudomonas and Xanthomonas). Additionally, some wood-associated pathogens such as Botryosphaeria, Phoma and Phomopsis have also been described. Due to important losses associated with these diseases, both chemical and biological control alternatives were evaluated for some of the above pathogens. Field and greenhouse experiments were conducted over different seasons. Trichoderma harzianum as a drench application resulted in an effective preventive control of Fusarium, with incidence and severity levels similar to the fungicide Benomyl. On the other hand, epidemiological studies indicated that the pathogen inoculum remained both in the soil and in weeds (Daucus carota and Rumex acetosella). According to field experiments, Trichoderma virens appears to be a good control alternative for Cladosporium and Alternaria. Trichoderma parceanamosum sprayed over the plants proved to be the most effective control treatment for Botrytis cinerea. Finally, cupric fungicides and Bacillus subtilis isolates did not provide an effective control against Pseudomonas in field conditions. New experiments should be conducted to obtain more conclusive results.

Advances in Apple Transformation Technology to Confer Resistance to Fungal Diseases in Apple Crops: A Chilean Perspective

Apple (Malus domestica Borkh.) is one of the most consumed fruit in the world. Genetic transformation is a key process to sustain this demand by permitting the potential enhancement of existing cultivars as well as the development of new cultivars resistant to pests, diseases, and storage problems that occur in the major production areas. This review summarizes the advances of genetic engineering applied to the development of resistant apple cultivars to fungus disease, with particular attention in the generation of apples resistant to Venturia inaequalis (Cooke) G.Winter, the main phytosanitary problem that affects apple crops in Chile.

Genetically modified crops in Chile

The economical, environmental and social impacts associated with genetically modifi ed (GM) crops are supported by the increased use of GM species by farmers. This increase in the use of GM species has included a global increase in both the number of hectares with GM crops and the number of countries using this technology. However, the use of GM crops has some drawbacks, due to the environmental risks associated with some of the events and social risks related to intellectual property rights issues and the monopoly associated with this technology. An overview of the current status of the use of GM crops in relation to the production, benefi ts, associated risks, intellectual property rights, legislation and regulatory framework is presented, focusing in the situation of ties crops in Chile. Los benefi cios economicos, ambientales y sociales asociados al cultivo de especies geneticamente modifi cados (GM) se ven respaldados por la creciente adopcion de estos por parte de los agricultores los que ha signifi cado, a nivel mundial, un incremento importante tanto en el numero de hectareas destinadas su cultivo como en el numero de paises que utilizan esta tecnologia. El uso de cultivos GM no ha estado exento de detractores, no solo por la posibilidad de riesgo tanto al medio ambiente como a la salud humana, sino porque la investigacion y desarrollo esta basada fuertemente en el patentamiento y la proteccion de la propiedad intelectual. Este trabajo presenta una resena general del estado actual del uso de cultivos GM en relacion a la produccion, benefi cios y riesgos asociados, derechos de propiedad intelectual, legislacion y marcos regulatorios, enfocado principalmente a la situacion de estos cultivos en Chile.

Flaxseed Response To N, P, and K Fertilization in South Central Chile

Flaxseed (Linum usitatissimum L.) is a minor crop in Chile. There is interest to increase the number of crops on the current rotation in South Central Chile and also to increase oilseed feedstocks for salmon feed. There is little information published about seed yield and oil content response to N, P, and K fertilizers on flaxseed in Chile. The objective of this study was to determine the effect of N, P, and K fertilization on flaxseed yield, oil content, and composition. The study was conducted at two locations during two growing seasons (environments), in Chillan 2004-2005, 2005-2006, and in Osorno 2004-2005, 2006-2007. Treatments were four levels of N (0, 100, 200, and 300 kg N ha-1), three levels of P (0, 100, and 200 kg P2O5 ha-1), and two levels of K (0 and 150 kg K2O ha-1). The design was a randomized complete block with a factorial arrangement of three factors (N, P, and K) and four replicates. According to the results, flaxseed yield improved as N rates increased. Physical optimum rate (rate at which maximum seed yield is obtained) was different depending on the location and year. Nitrogen rate increased oil content and yield up to 200 kg N ha-1. Oil composition was not affected by N, P, and K rates, or their interactions. The P and K nutrients did not have an effect on seed yield, oil content, oil yield, and oil composition.

Effect of the Irrigation Canal Network on Surface and Groundwater Interactions in the Lower Valley of the Cachapoal River, Chile

Agricultural production of high value crops in Chile's Central Valley is highly dependent on surface and groundwater resources. They are connected and together form an integrated hydrological system, the individual components of which have to be studied. This research is addressed to answering two questions: 1) to what extent do irrigation and canal seepage contribute to groundwater recharge and 2) what is the influence of the interactions between the Cachapoal River and ground water. The study was carried out from 2003 to 2007 in Peumo Valley (34.3° S, 71.3° W). In winter, the irrigation canal network intercepts and diverts surface runoff, which flows to flat areas and recharges groundwater. In summer, infiltration from the canals recharges the aquifer directly and partially compensates for water uptake from plants and evaporation. The effects of both interactions keep groundwater at a relatively constant level over the whole year. The water balance of the valley is strongly affected by agricultural practices, groundwater recharge mainly originating from irrigation loss (22%) and canal seepage (52%). It is important to know how management decisions, such as change in irrigation practices or canal lining, can affect the hydrological system and agricultural production within the valley.

Development of a biofertilizer based on filamentous nitrogen-fixing cyanobacteria for rice crops in Chile

The purpose of this study was to develop a biofertilizer based on filamentous nitrogen-fixing cyanobacteria selected from rice fields and to generate a technological package compatible with its use for the rice crop in Chile. Thirty-four Chilean rice fields, located between Maule and BioBio regions, were sampled during the 1998/1999 and 1999/2000 growing seasons. A total of 9 species and 3 varieties of cyanobacteria were found, and the nitrogen fixation rate under laboratory conditions was determined for 6 of them. Only 4 were used for the small-scale production of a biofertilizer, which was assayed in field trials. To check the efficiency of the biofertilizer during the rice crop, the nitrogen fixation rates in soil samples were estimated. Additionally, the biofertilizer application efficiency was tested in combination with nitrogen synthetic fertilizer, in rates that were previously established in field trials. Biofertilization allowed a decrease of up to 50% in the use of nitrogen synthetic fertilizer (50 kg N ha−1), resulting in the same grain yield (7.4 t ha−1) and quality in relation to the fertilized control. The use of biofertilizers based on local strains of cyanobacteria shows promise to increase nitrogen use efficiency in rice.

Foliar and ground-foraging predators of aphids associated with alfalfa crops in Chile: Are they good or bad partners?

Carabids and coccinellids are the most abundant aphid predators in alfalfa. Depending on the amount of prey consumed, the impact of their combined effect can be additive, antagonistic, or synergistic. Laboratory trials demonstrated that a higher proportion of Aphis craccivora Koch dropped from the alfalfa plants in the presence of coccinellids, and that the interaction between these predators was additive or synergistic, but never antagonistic, suggesting that they might be good partners in controlling aphids.

First Report of Lettuce big-vein virus and Mirafiori lettuce virus in Chile

Lettuce big-vein disease (BVD) is a serious virus disease of lettuce. Recent evidence has brought into question the role of Lettuce big-vein virus (LBVV) in the etiology of BVD, and suggested that Mirafiori lettuce virus (MiLV) and not LBVV is the causal agent of BVD (1,2). Lettuce plants (Lactuca sativa L.) with symptoms similar to those of BVD were observed during the winter of 2003 in open-field and hydroponic-grown lettuce plants located in the Chacabuco Province of central Chile. Symptomatic plants exhibited leaves with chlorotic vein banding that became ruffled and distorted. Symptoms were usually accompanied by reduced plant size and absence of head formation. Roots from symptomatic plants were analyzed by light microscopy-acid fuchsin staining. Zoosporangia and resting spores of Olpidium brassicae were identified on the basis of their morphology and structure. Additionally, soil transmission experiments were performed with 50 healthy lettuce seedlings replanted into contaminated soil collected from lettuce fields having symptomatic crops. After 3 weeks, one-half of the seedlings showed differing degrees of big-vein symptoms, and the presence of spores of O. brassicae was confirmed in the roots by light microscopy. Seedlings raised in sterilized soil showed no symptoms after the same period of time. On the basis of nucleotide sequences of LBVV and MiLV from the GenBank database, primers specific to the coat protein genes of each virus were designed as follows: MiLVV-CP1: 5'-CAAATCTGTCCACAATTCC-3'; MiLVV-CP2: 5'-TCTCACTTGAAAACCTTCC-3'; MiLVV-CP3: 5'-TTGCAACGTGATGAAACC-3'; MiLVV-CP4: 5'-AAAGAAGAGAAGCCTGTTCC-3'; LBVV-CP1: 5'-AAGCTTTCCGTACTGTCC-3'; LBVV-CP2: 5'-CCTTGATACAGTTTTTGACC-3'; LBVV-CP3: 5'-GTATGCTGATTTCTGTAGACC-3'; LBVV-CP4: 5'-TAGATGTTCTTCGCCACC-3'. The primers were used in reverse transcription-polymerase chain reaction (RT-PCR) assays with dsRNA as a template. Amplicons of the expected size were obtained in each of the five symptomatic plants analyzed, using each of the designated primer sets: MiLVV-CP1/MiLVV-CP2: 562 bp; MiLVV-CP3/MiLVV-CP4: 743 bp; LBVV-CP1/LBVV-CP2: 485 bp; and LBVV-CP3/ LBVV-CP4: 570 bp. No amplicons were obtained from healthy lettuce plants. The identity of both viruses was verified by cloning and sequencing of the amplicons. Nucleotide sequences were compared with those in the GenBank database. Sequences derived from the Chilean isolates resulted in identities of 87 to 97% for MiLV and 97 to 99% for LBVV. All samples analyzed were from the Chacabuco Province where 43% of the lettuce crops in Chile are grown. Thus, the impact that BVD may have on lettuce availability for local consumption may be significant. To our knowledge, this is the first report of Lettuce big-vein disease and Mirafiori lettuce virus infecting lettuce and the first report of BVD in Chile.

Characterization of Botrytis cinerea from Table Grapes in Chile Using RAPD-PCR.

Random amplified polymorphic DNA (RAPD) analysis was performed on 29 isolates of Botrytis cinerea Pers. ex Fr. isolated from table grapes (Vitis vinifera L.) and other crops in Chile with 29 decaprimers. No single primer was found to differentiate either the host or the geographical origin of each of the B. cinerea isolates tested. The DNA profiles obtained, particularly with primers OPA4 and OPA11, distinguished isolates of B. cinerea from other epiphyte fungi found on table grapes, including Alternaria alternata, Aspergillus niger, Cladosporium herbarum, Epiccocum nigrum, Rhizopus stolonifer, a Penicillium sp., and yeasts (Cryptococcus laurentii, Rhodotorula glutinis, and Saccharomyces cerevisiae). Regardless of host origin, primers OPA4 and OPA11 amplified a strong fragment of 1.2 kilobases (kb) and two fragments of 1.10 and 0.7 kb, respectively. These DNA fragments were obtained even when only one conidium of B. cinerea was in the test sample. Three main groups were clearly defined based on the genetic similarities found in additional RAPD analysis with 19 arbitrary decaprimers and 15 selected isolates of B. cinerea. The overall similarity coefficients (SC) between the groups obtained ranged from 0.326 to 0.891. Interestingly, all isolates from table grapes were included in group I (SC: 0.761 to 0.826), isolates from apple and tomato were in group II (SC: 0.739 to 0.848), while isolates from blueberry were either in group I (SC: 0.804) or III (SC: 0.673). Consequently, the genetic variability determined by RAPD analysis among these B. cinerea isolates suggested a possible host:pathogen relationship. However, further research is needed to clarify its pathological significance.

Comparative Protein Electrophoretic and Isoenzymic Patterns ofPhytophthora cryptogeaIsolates from Chilean Kiwifruit and North American Deciduous Fruits

Isolates of Phytophthora from fruit crops, previously identified as P. cryptogea on the basis of standard morphological criteria, were compared using electrophoretic patterns of total soluble mycelial proteins and isozyme analysis. According to these criteria, all 33 isolates recovered from kiwifruit in Chile were similar or identical to isolates from California recovered from kiwifruit, apple, and cherry. In contrast, the Chilean and California isolates appeared no more related to New York isolates of P. cryptogea than they were to isolates of P cactorum, P cinnamomi, and P megasperma that were similarly examined. Isolates identified as P. cryptogea from deciduous fruit crops in New York appear to belong to a different taxon than isolates of P cryptogea from fruit crops in Chile and California.

Ecological differences among Chilean populations of commercialGracilaria

Field farming ofGracilaria is gradually replacing use of the wild crop in Chile. The most popular planting method consists of establishing underground thallus systems for patches ofGracilaria on wave-sheltered, soft-bottom habitats. Commercial cultivation often involves transplanting vegetative material to distant places along the coast. This study shows that native populations possess some ecological differences that might affect cultivation success. Seven environmental factors were tested for their effects on growth of four geographically separated populations belonging to two species ofGracilaria. No specific or population differences were found under various temperature or salinity regimes. Specific differences occurred in responses to irradiance, daylength, sand burial and sand abrasion. Responses to epiphytes differed among both population and species. Epiphyte recruitment was inhibited by some populations and stimulated by others. Given the farming methods presently used in Chile, these results have ecological and economical importance, as they suggest that transplanting randomly from one to other type of habitat does not assure cultivation success.