DataSheet_2_Wild Helianthus species: A reservoir of resistance genes for sustainable pyramidal resistance to broomrape in sunflower.xlsx

Orobanche cumana Wall., sunflower broomrape, is one of the major pests for the sunflower crop. Breeding for resistant varieties in sunflower has been the most efficient method to control this parasitic weed. However, more virulent broomrape populations continuously emerge by overcoming genetic resistance. It is thus essential to identify new broomrape resistances acting at various stages of the interaction and combine them to improve resistance durability. In this study, 71 wild sunflowers and wild relatives accessions from 16 Helianthus species were screened in pots for their resistance to broomrape at the late emergence stage. From this initial screen, 18 accessions from 9 species showing resistance, were phenotyped at early stages of the interaction: the induction of broomrape seed germination by sunflower root exudates, the attachment to the host root and the development of tubercles in rhizotron assays. We showed that wild Helianthus accessions are an important source of resistance to the most virulent broomrape races, affecting various stages of the interaction: the inability to induce broomrape seed germination, the development of incompatible attachments or necrotic tubercles, and the arrest of emerged structure growth. Cytological studies of incompatible attachments showed that several cellular mechanisms were shared among resistant Helianthus species.

向日葵列当（Orobanche cumana Wall.）是向日葵栽培作物的主要有害生物之一。培育抗列当品种是防控该寄生性杂草的最有效手段。然而，毒性更强的列当种群不断演化，突破寄主的遗传抗性。因此，鉴定在寄生互作不同阶段发挥抗性作用的新型列当抗性资源，并将其聚合以提升抗性持久性，显得尤为关键。本研究通过盆栽试验，对源自16个向日葵属（Helianthus）物种的71份野生向日葵及其近缘种质开展了列当晚期出苗阶段的抗列当性筛选。从初始筛选中获得的、隶属于9个物种的18份抗性种质，进一步在寄生互作早期阶段开展表型分析：包括向日葵根系分泌物诱导列当种子萌发、列当与寄主根系的附着过程，以及根室试验（rhizotron assays）中的瘤状结构发育情况。研究结果显示，野生向日葵属种质是应对高毒性列当生理小种的重要抗性资源，其抗性作用于寄生互作的多个阶段：无法诱导列当种子萌发、形成不相容性附着结构或坏死性瘤状突起，以及抑制已出苗结构的生长。对不相容性附着结构的细胞学研究表明，不同抗性向日葵属物种共享多种细胞防御机制。