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A 10-day trip, encompassing 4600 km in the southeastern USA states of Tennessee, North Carolina, South Carolina, Georgia and Alabama, was made in October, 2003. Our primary objective was to locate populations of Helianthus eggertii, then on the USDI, Fish and Wildlife Service Threatened and Endangered Species list, and H. verticillatus, a candidate for endangered species status. Helianthus eggertii has since been de-listed (August 2005). An additional objective was to collect seeds of H. porteri, a species reclassified from Viguiera porteri, which is endemic to granite rock outcrops in Georgia. We collected seeds from 27 populations of the above three species plus three additional species, H. angustifolius, H. atrorubens, and H. smithii. Seed was deposited with the USDA-ARS North Central Regional Plant Introduction Station at Ames, Iowa (NCRPIS) from which 24 of the 27 collections are available for distribution. The three 'target' species were represented by 13 collections of H. eggertii, eight of H. porteri, and two of H. verticillatus; none of the three species were previously available from the NCRPIS sunflower collection. The availability of seed of these three species will allow researchers around the world the opportunity to investigate the potential of these wild Helianthus species to contribute useful traits to cultivated sunflower. Complete collection data has been loaded into the USDA-ARS Germplasm Resource Information Network (GRIN), and is available on the internet (www.ars-grin.gov). [ABSTRACT FROM AUTHOR]

The ability of some sunflower species to survive and thrive in shifting sand dunes with an annual precipitation of 50 mm could be of value for cultivated sunflower, a crop often grown in arid regions. The genus Helianthus comprises 51 species and 19 subspecies, with 14 annual and 37 perennial species, all native to North America. The objective of this study was to collect achenes from as many populations as possible of desert species, specifically annual H. anomalus, H. deserticola, H. niveus ssp. canescens, and perennial H. niveus ssp. tephrodes from the desert southwestern USA and make them available for future research and improvement of cultivated sunflower. The first exploration for H. anomalus and H. deserticola took place from September 16 to 23, 2000, covering 4100 km in three states, Utah, Arizona, and Nevada; while the second exploration concentrated on H. deserticola populations in west central Nevada, taking place between June 20 to 23 and August 15 to 18, 2005. The third exploration for H. niveus ssp. tephrodes took place from February 26 through March 5, 2005, covering 2200 km in southern California and adjacent Arizona. Only one population of H. deserticola from Utah and two populations of H. anomalus from Utah were collected in 2000. The 2005 exploration in Nevada resulted in the collection of achenes from 13 populations of H. deserticola. In 2005, five populations of H. niveus ssp. tephrodes were collected from the Alogodones Dunes in California. One population of H. niveus ssp. canescens was collected from Yuma, Arizona, near the US-Mexico border, with three additional populations collected from the Pinta Sands area of Arizona, which is the northernmost extension of the Gran Desierto of Sonora, Mexico. Achene samples of each collection are maintained and distributed from the USDA-ARS National Plant Germplasm System, North Central Regional Plant Introduction Station, Ames, Iowa. The limited number of desert species populations collected will provide basic germplasm for further research dealing with improving drought tolerance in cultivated sunflower. [ABSTRACT FROM AUTHOR]

Sunflower downy mildew (SDM) caused by Plasmopara halstedii , is a major disease of sunflower. Eleven resistance genes have been identified, but allelic relationships among these genes are not clear. This study examined the inheritance and allelic relationships of genes conferring resistance to SDM races 1, 2 and 3 (virulence phenotypes 100, 300 and 700, respectively) and confirmed a twelfth resistance gene. Three USDA Plant Introductions, AMES 3235, PI 497250, and PI 497938, and three released lines, RHA 266, RHA 274 and DM-2 were studied. RHA 266 has only the Pl 1 gene for race 1 resistance. Digenic inheritance of resistance was found in AMES 3235, PI 497250, and RHA 274. These lines have the Pl 1 and Pl 12 genes, conferring resistance to race 1, and the Pl 2 and Pl 11 genes, conferring resistance to race 2. DM-2 and PI 497938 have Pl 12 (but not Pl 1) for resistance to race 1, the Pl 12 gene (but not the Pl 2) for resistance to race 2, and Pl 5 for resistance to race 3. These resistance genes will serve as a foundation for future gene designations and genetic diversity studies of resistance to SDM. [ABSTRACT FROM AUTHOR]

Collections of the causal agent of sunflower downy mildew (Plasmopara balstedii) (PH) from several European and North and South American countries were used to inoculate a series of sunflower inbred lines to differentiate races. Race 3 was identified from Argentina; race 4 from France, Hungary, and Bulgaria; race 6 from Canada and France; and race 7 from Argentina. This is the first report of race 3 in South America and of race 4 in Europe, and is the first identification of races 6 and 7. Reactions of USDA lines RHA-274, RHA-325, and DM-2 differentiate races 2, 6, and 7, with RHA-274 resistant to all three. Thirty-three commercial hybrids from 11 countries were tested; 70 % were resistant to race 2, only 27 % had resistance to race 6, and none were resistant to race 4. Surveys to determine the relative proportions of the various races within each country are needed to assess their potential impact. The USDA lines HA-335, HA-336, HA-337, HA-338, HA- 339, RHA-340, HA-R4, and HA-R5 are resistant to all seven mildew races and could be utilized for the production of PH resistant hybrids. For die short term, it appears that seed treatment with metalaxyl may be die most effective control. [ABSTRACT FROM AUTHOR]

A total of 82 isolates of Plasmopara halsredii, collected from all production areas of Hungary between 1976 and 1993, were assessed for their virulence pattern on a standard set of sunflower differentials under glasshouse conditions. The isolates were classified into six pathogenic races each representing a particular virulence phenotype. From 1976 until 1988 all the isolates were found to be virulent only on sunflowers possessing no known resistance genes, thus classified as race I. There was an apparent shift in the virulence of the P. halstedii population collected after 1988. Six races (1 2, 3. 4. 8 and 9) were identified among the 45 samples collected between 1989 and 1993, with races 1 and 3 predominant, at a frequency of 35% each. While the increase in race virulence is undoubtedly due to selection imposed by resistant hybrids, the origin of the new races is unknown. Whether new races have arisen from the indigenous P. halstedii population, or whether they have been imported from abroad, can only be reliably determined by DNA techniques, such as fingerprinting. [ABSTRACT FROM AUTHOR]

Resistance to the prevailing races of sunflower rust, Puccinia helianthi Schw., is lacking in the commercial hybrids (Helianthus annuus L.). The objective of this study was to identify new sources of resistance to the four North American rust races in wild Helianthus species, and to determine their mode of inheritance. Seventy-eight accessions of H. annuus L., H. argophyllus Torrey and Gray, and H. petiolaris Nutt. were evaluated in the greenhouse. Resistance to races 1, 2, 3, and 4 was observed in 25, 28, 15, and 26 % of the plants, respectively, and 10% of the plants were resistant to all four races. Seven accessions that had a high percentage of resistant plants to all the four races were selected and one resistant plant from each accession was crossed with susceptible inbred line HA89. Three to four F[SUB1] plants resistant to all four races from each cross were backcrossed with HA89. F[SUB1] plants from PI-413118 × HA89 and PI 413175 × HA89 were resistant to all four races. The PI 413023 × HA89 F[SUB1] plants were 100 % resistant to races 3 and 4 and segregated in a 3 1 resistant (R) to susceptible (S) ratio to races 1 and 2. The other four F[SUB1] combinations segregated 3R : 1S ratios to all four races. BC[SUB1] F[SUB1] progenies revealed that plants from PI 413048, PI 413037, PI 413038, and PI 413171 used in the crosses possessed two dominant genes in heterozygous condition for resistance to each of the four races, whereas plants from PI 413023 possessed two dominant genes in heterozygous condition for resistance to each of races 1 and 2, and one dominant resistance gene in homozygous condition for each of races 3 and 4. Plants from PI 413118 and PI 413175 carried a single dominant gene in homozygous condition for resistance against each of the four races. [ABSTRACT FROM AUTHOR]

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The article presents the registration of two maintainer and three restorer Sclerotinia-tolerant oilseed sunflower germplasms. The two maintainers include HA 451 and HA 452. Two maintainer and three restorer oilseed sunflower germplasms were developed and released by the Agricultural Research Service of the U.S. Department of Agriculture and the North Dakota Agriculture Experiment Station. These germplasms were selected for their tolerance to Sclerotinia head and stalk rot which is a major sunflower disease. They also provide diversity for agronomic characteristics and oil quality. These germplasms are available for use by industry and public researchers to create hybrids, parental lines, or germplasms with increased tolerance to Sclerotinia head and stalk rot.

The article presents the registration of the Three Virus Resistant Sunflower Genetic Stocks, developed and released by the U.S. Department of Agriculture-Agricultural Research Service and the North Dakota Agricultural Experiment Station.

The article reports on the registration of HA 444, HA 445 and HA 446, maintainer and RHA 447, restorer on high oleic oilseed sunflower germplasms developed by the United States Department of Agriculture-ARD, Fargo and the North Dakota Agricultural Experiment Station in North Dakota. These germplasms have a high-oleic fatty acid concentration that is intended to be used by the sunflower industry and the public researchers. HA 44 is derived from F6 to F7 maintainer line which is selected from the cross HA 434/HA 406. The pedigree breeding method used to develop HA 444, HA 455, and HA 446 are the same. While RHA 447 is derived from F7 to F8 restorer line which is selected from the cross RHA 377/ RHA 348.

The article reports on the registration of HA 442, imidazolinone herbicide-resistant maintainer and RHA 443, fertility restorer of the oilseed sunflower germplasms developed by United States Department of Agriculture-ARD, Fargo and the North Dakota Agricultural Experiment Station in North Dakota. These germplasms were developed as the resistant to the imidazoline herbicide imazamox intended to be used by the sunflower industry and the public researchers. The HA 442 is derived from F6 to F7 maintainer lines which are selected from the cross HA 425/87CAEB//HA434/HA 412 with a high oleic fatty acid concentration. While RHA 443 was derived from F6 to F7 restorer line which is selected for the cross RHA 426/RHA 419//RHA 377/AS 4379.

The article reports on the registration of RHA 439, RHA 440, restorer and HA 441, sclerotinia tolerant oilseed sunflower germplasms developed by the United State Department of Agriculture-ARS, Fargo and North Dakota Agricultural Experiment Station in North Dakota. These germplasms are used to create hybrids and parental lines with improved Sclerotinia intended for the use of the sunflower industry and public researchers. The RHA 439 was derived from F7 to F8 restorer line selected from the cross RHA 377/AS 3211. The lines of RHA 439 and RHA 440 was selected by evaluating the testcross hybrids that were artificially inoculated under the mist irrigation. While 441 was derived from F7 to F8 maintainer lines that were selected form the cross of HA 412/SD.

The article presents the registration of three maintainer oilseed sunflower germplasms. The three maintainers include HA 456, HA 457 and HA 412 HO. The germplasms were developed and released by the Agricultural Research Service of the U.S. Department of Agriculture, and the North Dakota Agricultural Experiment Station. These high-oleic germplasms are available for use by industry and public researchers to create hybrid, parental lines, or germplasms with a midoleic or high-oleic fatty acid concentration in the oil.

The article presents the registration of a sunflower germplasm resistant to rust, downy mildew, and virus, developed and released by the U.S. Department of Agriculture-Agricultural Research Service and the North Dakota Agricultural Experiment Station.

Scierotinia head rot is a major disease of sunflower in the world, and quantitative trait loci (QTL) mapping could facilitate understanding of the genetic basis of head rot resistance and breeding in sunflower. One hundred twenty-three F2:3 and F2:4 families from a cross between HA 441 and RHA 439 were studied. The mapping population was evaluated for disease resistance in three field experiments in a randomized complete block design with two replicates. Disease incidence (DI) and disease severity (DS) were assessed. A genetic map with 180 target region amplification polymorphism, 32 simple sequence repeats, 11 insertion-deletion, and 2 morphological markers was constructed. Nine DI and seven DS QTL were identified with each QTL explaining 8.4 to 34.5% of phenotypic variance, suggesting the polygenic basis of the resistance to head rot. Five of these QTL were identified in more than one experiment, and each QTL explained more than 12.9% of phenotypic variance. These QTL could be useful in sunflower breeding. Although a positive correlation existed between the two disease indices, most of the respective QTL were located in different chromosomal regions, suggesting a different genetic basis for the two indices. [ABSTRACT FROM AUTHOR]