Sunflower Verticillium Wilt and Leaf Mottle (SVW), caused by Verticillium dahliae (Kleb.; Vd), is a soil-borne disease affecting sunflower worldwide. A single dominant locus, known as V1, was formerly effective in controlling North-American Vd races, whereas races from Argentina, Europe and an emerging race from USA overcome its resistance. This emphasizes the need for identifying broad-spectrum genetic resistance (BSR) sources. Here we characterize two sunflower mapping populations (MPs) for SVW resistance: a biparental MP and the association MP from the National Institute of Agricultural Technology (INTA), under field growing conditions. Nine field-trials (FTs) were conducted in highly infested fields in the most SVW-affected region of Argentina. Several disease descriptors (DDs), including incidence and severity, were scored across four phenological stages. Generalized linear models were fitted according to the nature of each variable, adjusting mean phenotypes for inbred lines across and within FTs. Comparison of these responses allowed the identification of novel BSR sources. Furthermore, we present the first report of SVW resistance heritability, with estimates ranging from 35 to 45% for DDs related to disease incidence and severity, respectively. This study constitutes the largest SVW resistance characterization reported to date in sunflower, identifying valuable genetic resources for BSR-breeding to cope with a pathogen of increasing importance worldwide.

The sunflower breeding carried out in Argentina constitutes a valuable contribution to the spreading of the crop both locally and internationally. Exchange among breeders at international level makes it possible to achieve objectives that would be restricted if only local germplasm were available (lack of variability). The National Institute of Agricultural Technology (INTA) has had a sunflower genetic breeding program at Pergamino Experimental Station (EEA) since 1939 and another program at Manfredi Experimental Station (EEA) since 1950 with the overall goal of contributing to increase the rate of genetic progress of the crop. At first the program development open pollination varieties using the populations which were introduced both by immigrants adapted to local conditions and by intercrossing them. With the development of cytoplasmic androsterility in the 1970s, the programs focused on producing inbred lines to develop hybrids. The varieties and lines were made available to other breeders in a scheme of exchange that allowed INTA, other national breeders and breeders from other countries to obtain new materials. In this way it became clear the great wealth of INTA germplasm for resistance to major crop diseases such as Verticillium wilt, rust and downy mildew. Other important traits improved were the increase of seed weight and tolerance to bird damage by adding striated seeds and decumbent heads. Also by its origin INTA germplasm enabled the increase of oil content, improvements in the quality and specialties (high oleic acid, confectionery) and tolerance to herbicides (imidazolinone), while maintaining the performance and health of the materials. This paper describes the origins and characteristics of INTA lines and also their use in other breeding programs for the creation of new cultivars.

Verticillium dahliae (Kleb) is a major sunflower disease (Helianthus annuus L.) in Argentina.The aim of this study was to evaluate different lines of EEA Pergamino sunflower breeding program for Verticillium reaction in order to find effective sources of Verticillium resistance.A method of seedling inoculation was applied to evaluate the performance of 689 lines. The scale was R (resistant), MR (medium resistant), MS (medium susceptible), AS (highly susceptible).The lines were grouped according to genetic background and percentages of lines in each class were calculated.The major variability was detected in P4. A higher percentage of resistance was obtained in selfed populations than in crosses of different lines.The crosses of local × exotic lines had better performance than the respective groups.Variability for Verticillium resistance was obtained in different sources of germplasm.

The aim of this work was to determine whether the local agroecological conditions of the northeast of the Province of Buenos Aires (33 deg 41 min S, 59 deg 41 min W) permit the organic production of leek (cv. Monstruoso de Carentan) seeds. In the 2000/01, 2001/02 and 2002/03 growth seasons, percentage flowering and seed yield (g m-2) and quality were recorded, the latter by determining the thousand grain weight and germination capacity. In the 2001/02 and 2002/3 seasons, the phenological stages of the crop were also determined, as well as the number of hours of cold temperatures experienced and the number of degree days. Significant differences between years were found in the number of days from 50% fruit setting to harvest, probably because three harvests were collected during the first season whereas only one was collected during the second and third. A total of 1,116 and 1,019 hours of cold temperatures and 925 and 1,127 degree days were recorded for 2001/2 and 2002/3 respectively. There were no significant differences between years for yield, percentage flowering or thousand seed weight (average values 78.53 gm-2, 93.36% and 3.55 g respectively). Differences in germination capacity were recorded, but Argentine legislative requirements were always surpassed. Seed yield and quality were comparable to figures cited in the literature. In conclusion, the agroecological conditions of the northeast of the Province of Buenos Aires allow the normal, organic cultivation of this leek cultivar for seed.

RESUMENEl significativo incremento de la siembra directa en Argentina y la anticipación de las fechas de siembra en suelos más fríos y húmedos, generó condiciones favorables para la difusión del downy mildew, una de las enfermedades potencialmente más destructivas del girasol causada por el hongo Plasmopara halstedii. Si bien existen cultivares de buen comportamiento frente al patóg-eno, la obtención de nuevas fuentes de resistencia reduce el riesgo de vulnerabilidad asociado al origen común del germoplasma. El objetivo del estudio fue detectar nuevas fuentes de resistencia a downy mildew en el germoplasma de INTA Pergamino tanto en materiales locales como exóticos. Se analizó la reacción de 1062 entradas de germoplasma de girasol de la EEA Pergamino frente downy mildew. Los análisis se realizaron en el laboratorio de Fitopatología EEA Pergamino desde el año 2001 al 2008 a través del método de inoculación de radícula (Gulya et al., 1991b). Solo el 1,7% del total de líneas evaluadas fue resistente a downy mildew. En el grupo exótico se obtuvo 1,99% de líneas resistentes, en el Local 0,34% y en Local × Exótico 2,29%. En el grupo exótico la resistencia provino de HA 335/HA 412(con resistencia a razas 700, 730 y 770) y de ND (North Dakota con resistencia a imidazolinonas). En el local la resistencia provino del compuesto P1 de la EEA Pergamino y en el grupo Local × Exótico de EstanzuelaxMP 557/ Negro Bellocq/KLM/HA 300, HA 341/ PEREDOVIK/P1 y P1/KLM/HA 300.Se obtuvo un buen "screening" de líneas de INTA para identificar nuevas fuentes de resistencia a la raza 770 de Plasmopara halstedii. La combinación de los grupos Local × Exótico fue la que permitió obtener el mayor número de materiales resistentes. Debería aumentarse el número de selecciones a partir EstanzuelaxMP 557/ Negro Bellocq/KLM/HA 300 por su buena performance y diferente origen. Los resultados son provechosos para el programa de mejoramiento de INTA. Se continuará con estudios para identificar los genes involucrados en la nueva fuente de resistencia. La detección de nuevas fuentes de resistencia permitirá incorporar el carácter a otros materiales, reduciendo la vulnerabilidad del germoplasma frente a la enfermedad