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 Pl_Arg. HA-R21 is an F₃-derived F₄ confection maintainer selection from the cross of HA-DM3 and HA-R8, carrying rust resistance genes R_13a 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.

中文翻译：

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抗锈病和霜霉病HA-R20和HA-R21糖果向日葵种质登记

锈病和霜霉病 (DM) 是全球向日葵 ( Helianthus annuus L.) 生产中的有害病害。疾病常常导致产量损失和种子质量下降。向日葵中宿主对DM和锈病的抗性是由单一显性基因介导的。为了更好地利用遗传抗性，基因金字塔是作物育种中的常见做法，以延长抗性的持久性和寿命。采用谱系育种方法和DNA标记辅助技术培育了两个糖果向日葵种质系HA-R20（注册号GP-387，PI 702361）和HA-R21（注册号GP-388，PI 702362）由 USDA-ARS 向日葵和植物生物学研究单位与北达科他州农业实验站于 2022 年 9 月合作发布。HA-R20 是来自HA-DM2 和 HA 杂交的F ₃衍生 F ₄糖果恢复剂选择-R8，携带锈病抗性基因R ₁₂和R ₁₅以及DM抗性基因Pl _Arg。HA-R21是来自HA-DM3和HA-R8杂交的F ₃衍生的F _{4糖果保持系选择，携带锈病抗性基因}R _13a和R ₁₅以及DM抗性基因P1 ₁₇。疾病反应和 DM 和锈病标记物测试证实，两种种质均在纯合状态下含有 DM 和锈病R基因，并且对迄今为止在北美发现的所有 DM 和锈病品种具有抗性。这些多重抗病品系将为向日葵产业提供持久的抗病来源，以实现作物的持续改良。