Genetic analysis of basal stalk rot resistance introgressed from wild Helianthus petiolaris into cultivated sunflower (Helianthus annuus L.) using an advanced backcross population

Authors: Talukder, Md Zahirul; Underwood, William; Misar, Christopher; LI, ZUEHUI - North Dakota State University; Seiler, Gerald; Cai, Xiwen; Qi, Lili

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2023
Publication Date: 10/18/2023
Citation: Talukder, M.I., Underwood, W., Misar, C.G., Li, Z., Seiler, G.J., Cai, X., Qi, L. 2023. Genetic analysis of basal stalk rot resistance introgressed from wild Helianthus petiolaris into cultivated sunflower (Helianthus annuus L.) using an advanced backcross population. Frontiers in Plant Science. 14. https://doi.org/10.3389/fpls.2023.1278048.
DOI: https://doi.org/10.3389/fpls.2023.1278048

Interpretive Summary: The soilborne fungal pathogen, Sclerotinia sclerotiorum causes basal stalk rot (BSR) disease in sunflower. It is a serious disease in the cool humid Northern Great Plains regions of the United States where most of the sunflower is grown. Disease management using fungicidal sprays is not available because the infection begins underground at the root system. Use of host genetic resistance is the most effective and environmentally friendly approach for BSR disease management. High levels of BSR resistance have been identified in the wild annual prairie sunflower, and successfully crossed with cultivated sunflower. Here we report the genetic mapping of the BSR resistance loci using DNA markers for further utilization of the resistance source in marker-assisted selection (MAS) breeding programs. A total of 14 resistance loci were identified to be potentially associated with BSR resistance in the sunflower genome and tightly linked DNA markers were detected. Molecular markers flanking the identified BSR resistance loci will facilitate MAS breeding to combat the destructive BSR disease in sunflower.

Technical Abstract: Sclerotinia sclerotiorum is a serious pathogen causing severe basal stalk rot (BSR) disease on cultivated sunflower (Helianthus annuus L.) that leads to significant yield losses due to insufficient resistance. The wild annual sunflower species H. petiolaris, commonly known as prairie sunflower is known for its resistance against this pathogen. The genetics of BSR resistance is quantitative and conditioned by many small effect genes. The objective of this study was to identify loci governing BSR resistance derived from H. petiolaris using a quantitative trait locus (QTL) mapping approach. An advanced backcross population (AB-QTL) with 174 lines derived from the cross of inbred line HA 89 with H. petiolaris PI 435843 was evaluated for BSR resistance in the field during 2017-2019, and in the greenhouse in 2019. Highly significant genetic variations (p<0.001) were observed for BSR disease incidence (DI) in all field seasons, and disease rating (DR) and area under the disease progress curve (AUDPC) in the greenhouse with a moderately high broad-sense heritability (H2) of 0.61 for all BSR resistance parameters. The parents and the AB-QTL population were genotyped using genotyping-by-sequencing. A genetic linkage map spanning 997.51 cM was constructed using 1,150 SNP markers mapped on 17 sunflower chromosomes. A total of 14 QTL associated with BSR resistance were detected on nine chromosomes, each explaining a proportion of the phenotypic variation ranging from 3.5% to 28.1%. Of the 14 QTL, eight QTL were detected for BSR DI measured in the field and six were detected for traits measured in the greenhouse. Eleven of the 14 QTL had favorable alleles from the H. petiolaris parent conferring increased BSR resistance.