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Botrytis cinerea Pers. is a necrotrophic and polyphageous pathogen economically important on soft fruits and crops producing severe agricultural losses. The Chilean strawberry, Fragaria chiloensis (L.) P. Mill. is one of the wild parents of commercial strawberry and has the capacity to tolerate the infection from the pathogenic fungus. A study was performed to make a genetic analysis of wild and cultivated individuals collected from three different regions of Central South Chile and compare the Botrytis infection performance. The dominant ISSR markers were used to generate the genetic fingerprinting and the native samples were contrasted against the commercial Fragaria × ananassa Duch. The samples from Contulmo presented the lowest diversity within population and the highest diversity between populations, but at the same time showed the highest tolerance to Botrytis infection. Infected leaves and fruits from F. × ananassa showed 3.6% of the area covered by the fungus, three days after inoculation, while the plants from Contulmo showed 3.3% of the area covered by the pathogen, five days after inoculation. The plants from Contulmo were classified as highly tolerant (HT), tolerant (T), moderately tolerant (MT), and susceptible (S) where 50% of plants belonged to the group of tolerant. The results, highly significant (p ≤ 0.01), indicate that the samples of F. chiloensis from Contulmo are more genetically homogeneous and can be classified as tolerant to the infection by Botrytis cinerea.Additional key words: grey mould, native strawberry, resistance. ResumenDiversidad genética en frutilla chilena (Fragaria chiloensis): respuesta diferencial a la infección con Botrytis cinerea Botrytis cinerea Pers. es un patógeno necrótrofo y polífago de importancia económica en cultivos y frutales, ocasionando importantes pérdidas en agricultura. La frutilla chilena, Fragaria chiloensis (L.) P. Mill., antecesor silvestre de la frutilla comercial, tiene la capacidad de tolerar la infección de una serie de hongos patogénicos. En este estudio se efectuó un análisis genético de plantas de frutilla chilena silvestres y cultivadas, recolectadas en tres diferentes regiones de la zona centro sur de Chile, en cuanto a su comportamiento frente a la infección de Botrytis. Los marcadores dominantes ISSR fueron utilizados para generar el patrón genética y las muestras de frutilla chilena fueron comparadas con las de Fragaria × ananassa Duch. Las muestras de Contulmo mostraron la más baja diversidad dentro de la población y la mayor entre poblaciones. Al mismo tiempo presentaron la mayor tolerancia a la infección con Botrytis. Las hojas y frutos de F. × ananassa, mostraron, tres días después de la inoculación, un 3,6% de su área cubierta por el patógeno. Por el contrario en las plantas recolectadas en Contulmo la infección fue más lenta, observándose un 3,3% del área cubierta por el patógeno, cinco días después de la inoculación. Las plantas de Contulmo fueron clasificadas como altamente tolerantes, tolerantes, moderadamente tolerantes y...

Previously, we demonstrated that Broad bean mottle virus (BBMV), a member of the genus Bromovirus, could accumulate RNA 2-derived defective interfering (DI) RNAs during infection. In this work, we study how host and environmental factors affect the accumulation of DI RNAs. Serial passages of BBMV through selected plant species reveal that, with low-multiplicity inocula, some systemic hosts (Vicia faba, Nicotiana clevelandii, and N. tabacum cv. Samsum) support DI RNA accumulation after the first passage cycle but other hosts (Phaseolus vulgaris, Pisum sativum, and Glycine max) do not. However, several passages with the high-multiplicity inocula can generate DI RNAs in pea plants. Local lesion hosts (Chenopodium quinoa, C. amaranticolor, and C. murale) remain free of the DI RNA components. The size of the de novo-formed DI RNAs depends on the host and on environmental conditions. For instance, broad bean plants cultivated in a greenhouse or in a growth chamber at 20 degrees C accumulated DI RNAs of 2.4 or 1.9 kb in size, respectively. A reverse trend was observed in pea plants. Lower temperatures greatly facilitated the formation of DI RNAs in broad bean and pea hosts after the first passage. The importance of these findings for the studies on DI RNAs are discussed.

No abstract

Wild and cultivated Fragaria chiloensis ssp. chiloensis (Fcc) plants were collected at different locations in southern Chile in order to determine the current viral status of this native strawberry. The following aphidborne viruses (ABVs): Strawberry mild yellow edge virus (SMYEV), Strawberry mottle virus (SMoV), Strawberry crinkle virus (SCV) and Strawberry vein banding virus (SVBV), were found in wild and cultivated Fcc plants, but severe symptoms were not associated with viral infection. Furthermore, partial gene sequences of these ABV isolates were determined and displayed a high degree of conservation with virus isolates reported previously. In addition, partial gene sequences of SCV and SVBV from southernmost South American populations of Fcc are described for the first time. High-throughput parallel sequencing (Illumina) of double-stranded RNA was used to provide viral profiles of Fcc from different locations. Although strong evidence of novel viruses affecting Fcc was not found, it was confirmed that ABVs are the most frequent viruses affecting this subspecies. The information provided will help in the development of high-quality molecular tools for virus detection and control in Fcc.

A viral vector that expressed foreign genes was engineered using a cDNA clone of broad bean mottle bromovirus (BBMV) defective interfering (DI) RNA. The expression vector required an active ORF to ensure efficient accumulation and replication in the host plants. After mechanical inoculation with BBMV RNAs, expression of the green fluorescent protein (GFP) reporter was driven by DI RNA constructs during consecutive passages through broad bean plants. Our data prove that BBMV DI RNAs, whose yield is similar to the virus genomic components, are useful as gene vectors after mechanical inoculation on legume plants.

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At the present time, fl oriculture occupies 2,124 ha, of which 180 ha are devoted to carnations. Almost all carnations produced are sold in the domestic market. Several diseases affect carnations, among them fairy-ring leaf spot (Cladosporium echinulatum), the most important foliar disease in Chile. Different control alternatives for fairy-ring spot were evaluated on the carnation cv. Sarinah in terms of disease incidence and severity. The study was performed in June-August 2003 with a commercial carnation planting in a greenhouse located in Champa (33º 49` S, 70º 45` W) that in previous growing seasons reported a high incidence of fairy-ring leaf spot. The treatments included ammonium bicarbonate (5 g L -1 ), sodium bicarbonate (5 g ּ L -1 ), ammonium bicarbonate + mineral oil Srpinguill (5 g L -1 + 10 mL ּ L -1 ), sodium bicarbonate + mineral oil Srpinguill (5 g L -1 + 10 mL ּ L -1 ), mineral oil Srpinguill (10 mL L -1 ), mancozeb (2 g ּ L -1 ), copper oxichloride (2 g ּ L -1 ), pentahydrated copper sulfate (1 mL L -1 ), Trichoderma virens strain Sherwood (Trichonativa) (5 mL ּ L -1 ) and an untreated control. Based on the results obtained, the most effective treatments were sodium bicarbonate and T. virens. Mancozeb, copper oxichloride, sodium bicarbonate + mineral oil Springuill, ammonium bicarbonate, mineral oil Springuill and pentahydrated copper sulfate were ineffective in controlling carnation fairy-ring leaf spot.