Search

Sunflower (Helianthus L.) production ranked third in global oilseed production in 2021. Downy mildew (DM), caused by the oomycete pathogen Plasmopara halstedii (Farl.) Berl. et de Toni, is a major constraint for worldwide sunflower production, causing significant yield losses in susceptible hybrids. The search for new sources of resistance to DM is the primary objective of all sunflower breeding programs. Germplasms HA‐DM15 (Reg. no. GP‐385, PI 702359) and HA‐DM16 (Reg. no. GP‐386, PI 702360) were developed by introgressing two new DM resistance genes, Pl37 and Pl38, from the wild sunflower species H. annuus and H. praecox into oilseed sunflower, respectively. The BC1F3‐derived HA‐DM15 harboring the Pl37 gene was selected from the cross of HA 89//NMS HA 89/wild H. annuus PI 435417. The germplasm line HA‐DM16 carrying the Pl38 gene is an improved oilseed derivative of Rf PRA‐417 with DM resistance originally derived from the wild H. praecox PRA‐417 from the cross of cytoplasmic male sterile (CMS) HA89*2/wild H. praecox PRA‐417. HA‐DM15/Pl37 and HA‐DM16/Pl38 are immue to the most predominant and virulent DM races idenfied in North America and Europe. Pl37 and Pl38 have been genetically mapped to sunflower chromosomes 4 and 2, respectively, with single nucleotide polymorphism markers linked to the both genes facilitating their transfer to elite sunflower lines by marker‐assisted selection, providing new and diverse sources for sunflower DM‐resistance breeding. Core Ideas: Resistance to downy mildew in HA‐DM15 and HA‐DM16 was introgressed from two wild sunflower species.HA‐DM15 and HA‐DM16 harbor the new downy mildew resistance genes Pl37 and Pl38, respectively.HA‐DM15 and HA‐DM16 are immune to the most predominant and virulent P. halstedii races found in the United States and Europe. [ABSTRACT FROM AUTHOR]

Rust and downy mildew (DM) are detrimental diseases in global sunflower (Helianthus annuus L.) production. Disease often results in yield loss and reduced seed quality. Host resistance to DM and rust is mediated by single dominant genes in sunflower. To better utilize genetic resistance, gene pyramiding is a common practice in crop breeding to extend the durability and longevity of resistance. Two confection sunflower germplasm lines, HA‐R20 (Reg. no. GP‐387, PI 702361) and HA‐R21 (Reg. no. GP‐388, PI 702362), were developed using the pedigree breeding method and DNA marker‐assisted selection and released by the USDA‐ARS Sunflower and Plant Biology Research Unit in collaboration with the North Dakota Agricultural Experiment Station in September 2022. HA‐R20 is an F3‐derived F4 confection restorer selection from the cross of HA‐DM2 and HA‐R8, carrying rust resistance genes R12 and R15 and DM resistance gene PlArg. HA‐R21 is an F3‐derived F4 confection maintainer selection from the cross of HA‐DM3 and HA‐R8, carrying rust resistance genes R13a and R15 and DM resistance gene Pl17. Disease reaction and marker testing for DM and rust confirmed that both germplasms harbor DM and rust R genes in the homozygous condition and are resistant to all DM and rust races identified in North America to date. These multiple disease‐resistant lines will provide the sunflower industry with durable disease‐resistant sources for the continued improvement of the crop. Core Ideas: Two confection sunflower germplasms, HA‐R20 and HA‐R21, were developed by marker‐assisted selection.HA‐R20 (R12/R15/PlArg) and HA‐R21 (R13a/R15/Pl17) harbor two rust and one downy mildew R genes each.Both lines have durable resistance to all rust and downy mildew races identified to date. [ABSTRACT FROM AUTHOR]

Downy mildew (DM), caused by the obligate pathogen Plasmopara halstedii (Farl.) Berl. & de Toni, is a worldwide yield‐limiting disease of sunflower (Helianthus annuus L.). To obtain durable DM resistance in sunflower hybrids, there is a need to stack new resistance genes into the best available germplasm. The DM resistance genes Pl8, Pl17, and Pl18 were recently fine mapped to sunflower chromosomes 13, 4, and 2, respectively. The current study pyramided these genes into a single genotype by marker‐assisted selection. Three oilseed sunflower germplasms, HA‐DM9 (Reg. no. GP‐381, PI 700009), HA‐DM10 (Reg. no. GP‐379, PI 700004), and HA‐DM11 (Reg. no. GP‐380, PI 700005), are dual DM‐resistant germplasm lines developed and have been released by the USDA‐ARS, Sunflower and Plant Biology Research Unit in collaboration with the North Dakota Agricultural Experiment Station in 2021. The three lines, HA‐DM9 (Pl8Pl8/Pl17Pl17), HA‐DM10 (Pl8Pl8/Pl18Pl18), and HA‐DM11 (Pl17Pl17/Pl18Pl18), each stacked two different DM genes, providing broad resistance to all P. halstedii races identified in North America and Europe so far, and can be used in sunflower breeding programs to enhance DM resistance. Core Ideas: Three oilseed sunflower germplasms with dual resistance to downy mildew were developed using marker‐assisted selection.HA‐DM9, HA‐DM10, and HA‐DM11 each pyramided two different downy mildew R genes.All germplasms exhibit resistance to all known downy mildew races identified in North America and Europe. [ABSTRACT FROM AUTHOR]

Key message: Two new downy mildew resistance genes, Pl37 and Pl38, were introgressed from wild sunflower species into cultivated sunflower and mapped to sunflower chromosomes 4 and 2, respectively Downy mildew (DM), caused by the oomycete pathogen Plasmopara halstedii (Farl.) Berl. & de Toni, is known as the most prevalent disease occurring in global sunflower production areas, especially in North America and Europe. In this study, we report the introgression and molecular mapping of two new DM resistance genes from wild sunflower species, Helianthus annuus and H. praecox, into cultivated sunflower. Two mapping populations were developed from the crosses of HA 89/H. annuus PI 435417 (Pop1) and CMS HA 89/H. praecox PRA-417 (Pop2). The phenotypic evaluation of DM resistance/susceptibility was conducted in the BC1F2-derived BC1F3 populations using P. halstedii race 734. The BC1F2 segregating Pop1 was genotyped using an Optimal GBS AgriSeq™ Panel consisting of 768 mapped SNP markers, while the BC1F2 segregating Pop2 was genotyped using a genotyping-by-sequencing approach. Linkage analysis and subsequent saturation mapping placed the DM resistance gene, designated Pl37, derived from H. annuus PI 435417 in a 1.6 cM genetic interval on sunflower chromosome 4. Pl37 co-segregated with SNP markers SPB0003 and C4_5738736. Similarly, linkage analysis and subsequent saturation mapping placed the DM resistance gene, designated Pl38, derived from H. praecox PRA-417 in a 0.8 cM genetic interval on sunflower chromosome 2. Pl38 co-segregated with seven SNP markers. Multi-pathotype tests revealed that lines with Pl37 or Pl38 are immune to the most prevalent and virulent P. halstedii races tested. Two germplasm lines, HA-DM15 with Pl37 and HA-DM16 with Pl38, were developed for use in sunflower DM-resistance breeding. [ABSTRACT FROM AUTHOR]

Key message: We have mapped a new downy mildew resistance gene, Pl35, derived from wild Helianthus argophyllus to sunflower linkage group 1. New germplasms incorporating the Pl35 gene were developed for both oilseed and confection sunflower Sunflower downy mildew (DM), caused by the oomycete pathogen Plasmopara halstedii, is an economically important and widespread sunflower disease worldwide. Non-race-specific resistance is not available in sunflower, and breeding for DM resistance relies on race-specific resistance to control this disease. The discovery of the novel DM resistance genes is a long-term task due to the highly virulent and aggressive nature of the P. halstedii pathogen, which reduces the effectiveness of resistance genes. The objectives of this study were to: (1) transfer DM resistance from a wild sunflower species Helianthus argophyllus (PI 494576) into cultivated sunflowers; (2) map the resistance gene; and (3) develop diagnostic single-nucleotide polymorphism (SNP) markers for efficient targeting of the gene in breeding programs. The H. argophyllus accession PI 494576 previously identified with resistance to the most virulent P. halstedii race 777 was crossed with oilseed and confection sunflower in 2012. Molecular mapping using the BC2F2 and BC2F3 populations derived from the cross CONFSCLB1/PI 494576 located a new resistance gene Pl35 on linkage group 1 of the sunflower genome. The new gene Pl35 was successfully transferred from PI 494576 into cultivated sunflowers. SNP markers flanking Pl35 were surveyed in a validation panel of 548 diversified sunflower lines collected globally. Eleven SNP markers were found to be diagnostic for Pl35 SNP alleles, with four co-segregating with Pl35. The developed oilseed and confection germplasms with diagnostic SNP markers for Pl35 will be very useful resources for breeding of DM resistance in sunflower. [ABSTRACT FROM AUTHOR]

Wild Helianthus species possess valuable resistance genes for sunflower broomrape (Orobanche cumana Wallr.), especially the 39 largely underutilized perennial species. Resistance to race F has been transferred into a cultivated background via bridging of interspecific amphiploids. More recently, a single dominant gene resistant to race G was identified in annual H. debilis ssp. tardiflorus and transferred into cultivated HA 89. Interspecific crosses between wild annual Helianthus species and cultivated lines are relatively easy compared to those involving wild perennial species, which were made easier only after the development of embryo rescue techniques. Interspecific amphiploids resulting from colchicine treatment of F1 hybrids provide bridging materials for transferring genes without relying on embryo rescue. Among the diploid, tetraploid, and hexaploid perennial species, the speed of gene utilization follows the ploidy level of diploids, tetraploids, and hexaploids due to the time-consuming backcrosses required to eliminate the extra chromosomes in the latter two groups. In the development of pre-breeding materials, the retention rate of genetic material of the wild species is another concern with each additional backcross. For crosses involving tetraploid and hexaploid wild perennials, the use of 2n = 51 chromosome F1 or BC1F1 generation, as pollen source, could accelerate chromosome reduction to 2n = 34 in BC1F1 or BC2F1, resulting in useful materials with fewer backcrosses for trait selection. [ABSTRACT FROM AUTHOR]

A five year field trial evaluated 71 oilseed sunflower, Helianthus annuus L., accessions, 32 breeding lines, and 25 interspecific crosses for resistance to infestation by naturally occurring populations of the banded sunflower moth, Cochylis hospes Walsingham (Lepidoptera: Tortricidae), in North Dakota. Germplasm with resistance to attack by the banded sunflower moth and subsequent larval feeding damage in the seeds was identified. PI 251902 had less than 10% feeding damage per head in all five years of testing and less than 6% in three of the five years. PI 372259 and PI 170401 exhibited 12% or less seed damage in three years of evaluation and PI 253776 had only 3% damage in two of the three years and was the least damaged in 2004. Four other accessions (PI 170385, PI 291403, PI 494859, and PI 505651) revealed resistance in three of five years. A number of the interspecific crosses which were retested based on earlier results showed reduced seed damage in 2003, but subsequently exhibited much greater damage the following year due to higher populations of banded sunflower moth. Hybrid 894 was earlier used by others as a susceptible check; however, in the current investigation, this hybrid consistently had the lowest average seed damage from C. hospes feeding among the germplasm evaluated. Results from this investigation indicate that there is potential for developing resistant genotypes with reduced feeding injury that will help sunflower producers reduce yield loss due to the banded sunflower moth. In addition, plant resistance can effectively be combined with delayed planting to decrease densities of C. hospes, thus reducing crop losses without disrupting the control of the larvae by parasitoids. [ABSTRACT FROM AUTHOR]

Within the past decade, the desire for alternative sources of fuels, chemicals, feeds, and other materials has received increased attention. Wild sunflower species have the potential to contribute to these renewable resources. During the past three decades, the narrow genetic base of cultivated sunflower has been broadened by the infusion of genes from wild relatives, which have provided a continuous source of agronomic traits for crop improvement. The genus Helianthus is composed of 51 species and 19 subspecies with 14 annual and 37 perennial species. Although oil concentrations of up to 37 g/kg have been reported in whole plants of one wild sunflower species, H. ciliaris, the achenes are the primary storage tissue for oil. The fatty acid composition of the achene oil determines its suitability for either food or industrial uses. Considerable variability has been reported in fatty acid composition of oil in achenes of the wild species. Other natural products may also be of economic value from the wild sunflower species. A natural rubber concentration of 19 g/kg has been reported in the whole plant of wild perennial H. radula with more than 92% pure rubber. Polyphenol yields of wild sunflower biomass are moderate, with H. strumosus yielding 139 g/kg. Hydrocarbon yields for wild sunflower biomass are average for most species, with H. salicifolius having the highest yield of 16 g/kg. The sugars in the stalks and tubers of Jerusalem artichoke (H. tuberosus) have been suggested as a potential source for bioethanol production. Jerusalem artichoke has been evaluated for inulin and sugar yield from stalks, yielding 10.4 and 8.0 t/ha, respectively, while tubers yield 13.7 t/ha of inulin and 13.3 t/ha of fructose. Biomass production has also been investigated in Jerusalem artichoke. Dry matter forage yields of 3.0 to 9.9 t/ha and tuber yields of 2.8 to 12.8 t/ha have been reported. Further research will be needed to assess the potential use of wild species for industrial purposes through selection and breeding. [ABSTRACT FROM AUTHOR]

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]

Copyright of Helia is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Helia is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Helia is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Respiration is responsible for much of the sucrose loss that occurs during sugarbeet (Beta vulgaris L.) storage. Genotypes with reduced storage respiration rates would provide an efficient method for reducing sucrose losses. However, the current techniques for measuring storage respiration are not adapted easily to breeding programs. Internal CO2 concentration has been recommended as an efficient method for measuring the respiration rate of individual sugar- beet roots in storage. This study examined the effectiveness of internal CO2 concentration as a selection criterion for reducing respiration rate of sugarbeet during storage. Lines resulting from four cycles of divergent selection for internal CO2 concentration were evaluated along with commercial hybrids and low internal CO2 germplasm lines. Selection was effective in shifting internal CO2 concentration. Relative differences in internal CO2 concentration were consistent throughout the 3-year study. Neither the fourth-cycle selections for low nor the fourth-cycle selections for high internal CO2 concentration were significantly different from the original population for evolved CO2. This lack of a close relationship between internal and evolved CO2 indicated that internal CO2 concentration is not an effective selection criterion in a breeding program. [ABSTRACT FROM AUTHOR]

The sexual transfer of genes between taxa possessing different structural karyotypes must involve the passage of genes through a chromosomal sterility barrier. Yet little is known about the effects of structural differences on gene introgression within or adjacent to the rearranged chromosomal fragments or about the patterns of introgression in collinear regions. Here, we employ 197 mapped molecular markers to study the effects of chromosomal structural differences on introgression in backcrossed progeny of the domesticated sunflower, Helianthus annuus, and its karyotypically divergent wild relative, H. petiolaris. Forty percent of the genome from the seven collinear linkages introgressed, whereas only 2.4% of the genome from the 10 rearranged linkages was transferred. Thus, chromosomal rearrangements appear to provide an effective mechanism for reducing or eliminating introgression in rearranged chromosomal segments. On the other hand, observations that 60% of the markers from within the collinear portion of the genome did not introgress suggests that genic factors also resist introgression in Helianthus. That is, selection against H. petiolaris genes in concert with linkage may have reduced or eliminated parts of the genome not protected by structural changes. Thus, barriers to introgression in Helianthus appear to include both chromosomal structural and genic factors.