Prevalence and Incidence of Sunflower Downy Mildew in North Dakota Between 2001 and 2011

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.

Section: Methodsmentioning

confidence: 99%

Registration of HA‐R20 and HA‐R21 confection sunflower germplasms resistant to rust and downy mildew

Ma,

Li,

Seiler

et al. 2023

“…Currently, a total of 44 P. halstedii races have been recoded worldwide, and the highest pathogenic diversity of P. halstedii has been found in Canada, the United States, and France (Gulya, 2007; Trojanová et al., 2017; Viranyi et al., 2015). Many Pl genes in the sunflower gene pool have been overcome in the field due to the rapid adaptation of pathogens (Gascuel et al., 2015; Gilley et al., 2020; Gulya et al., 2010, 2011). Current efforts to breed for durable DM resistance focus on pyramiding effective major R genes to extend the durability of resistance where sunflower hybrids with the single gene components are not widely deployed.…”

Section: Introductionmentioning

confidence: 99%

Registration of HA‐DM9, HA‐DM10, and HA‐DM11 oilseed sunflower germplasms with dual resistance to sunflower downy mildew

Seiler

2023

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.

“…The fungicide metalaxyl has been widely used as a seed treatment to prevent primary infection to DM in sunflower production since 1985. However, P. halstedii quickly developed resistance against the metalaxyl in France (Albourie et al., 1998), the United States (Gulya, 2001, 2002; Gulya et al., 1999), Spain (Molinero‐Ruiz et al., 2003; Ruiz et al., 2000), and Germany (Spring et al., 2006), dramatically increasing DM severity in the fields. Host resistance to DM in sunflower is controlled by single dominant genes, designated Pl .…”

Section: Introductionmentioning

confidence: 99%

Registration of HA‐DM15 and HA‐DM16 oilseed sunflower germplasms with resistance to sunflower downy mildew

Qi,

Seiler

2023

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.