Registration of oilseed sunflower germplasms HA-BSR6, HA-BSR7, and HA-BSR8 highly resistant to sclerotinia basal stalk rot and downy mildew

Authors: TALUKDER, ZAHIRUL - North Dakota State University; LONG, YUNMING - North Dakota State University; Seiler, Gerald; Underwood, William; Qi, Lili

Submitted to: Journal of Plant Registrations
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2019
Publication Date: 7/18/2019
Citation: Talukder, Z.I., Long, Y.M., Seiler, G.J., Underwood, W., Qi, L.L. 2019. Registration of oilseed sunflower germplasms HA-BSR6, HA-BSR7, and HA-BSR8 highly resistant to sclerotinia basal stalk rot and downy mildew. Journal of Plant Registrations. https://doi.org/10.3198/jpr2018.10.0071crg.
DOI: https://doi.org/10.3198/jpr2018.10.0071crg

Interpretive Summary: Sclerotinia basal stalk rot (BSR) and downy mildew (DM) are two important diseases of sunflower in temperate production environments. Exploitation of host resistance is the most economical and environmentally friendly management approach to reduce the damage caused by these diseases. Resistances to these diseases are available in the crop wild relatives of cultivated sunflower. We developed three sunflower germplasm lines, HA-BSR6, HA-BSR7 and HA-BSR8, highly resistant to both BSR and DM diseases. BSR resistance was introgressed from a wild sunflower species Helianthus praecox, while the DM resistance gene was deployed from an inbred line, HA 458. These germplasm lines consistently showed high levels of BSR resistance in inoculated field nurseries across multiple environments in North Dakota and Minnesota during 2012 to 2015. Greenhouse tests revealed that the DM resistance gene was present in all three germplasm lines confirmed by DNA markers. The three germplasm lines can be used in sunflower breeding programs to develop hybrids with resistance against both Sclerotinia BSR and DM.

Technical Abstract: Sclerotinia basal stalk rot (BSR) and downy mildew (DM) are agronomically important diseases of sunflower worldwide. Three sunflower germplasm lines, HA-BSR6 (Reg. No. -----, PI 685019), HA-BSR7 (Reg. No. -----, PI 685020), and HA-BSR8 (Reg. No. -----, PI 685021) were developed with dual resistance to both BSR and DM. BSR resistance of the germplasm lines was transferred from the wild annual sunflower H. praecox subsp. runyonii Engelmann & A. Gray (Heiser) (PI 468853), and DM resistance was introgressed from inbred line HA 458 possessing the Pl17 gene. The germplasms were tested for BSR resistance in inoculated field trials in multiple locations over four years. All three germplasm lines showed significantly higher BSR resistance (p < 0.05) than the recurrent parent and the checks across environments, with a four-year mean disease incidence (DI) ranging from 1.2% to 4.8%, while Cargill 270 (susceptible hybrid check) and HA 89 (recurrent parent) had DI 36.1% and 31.0%, respectively, and HA 441 (resistant inbred check) and Croplan 305 (resistant hybrid check) had DI 19.5% and 11.6%, respectively. Whole genome scan using genotyping-by-sequencing revealed the presence of H. praecox subsp. runyonii chromosome segments in HA-BSR6, HA-BSR7, and HA-BSR8, which are potentially associated with BSR resistance. Phenotypic evaluation identified DM resistance in all three germplasm lines with flanking DNA markers confirming the presence of the Pl17 gene in the lines. These germplasm lines can be used in sunflower breeding programs for pyramiding both BSR and DM resistance genes.