Unraveling the Sclerotinia Basal Stalk Rot Resistance Derived From Wild Helianthus argophyllus Using a High-Density Single Nucleotide Polymorphism Linkage Map

Abstract

Basal stalk rot (BSR), caused by the fungus Sclerotinia sclerotiorum, is a serious disease of sunflower (Helianthus annuus L.) in the humid temperate growing areas of the world. BSR resistance is quantitative and conditioned by multiple genes. Our objective was to dissect the BSR resistance introduced from the wild annual species Helianthus argophyllus using a quantitative trait loci (QTL) mapping approach. An advanced backcross population (AB-QTL) with 134 lines derived from the cross of HA 89 with a H. argophyllus Torr. and Gray accession, PI 494573, was evaluated for BSR resistance in three field and one greenhouse growing seasons of 2017–2019. Highly significant genetic variations (p < 0.001) were observed for BSR disease incidence (DI) in all field screening tests and disease rating and area under the disease progress curve in the greenhouse. The AB-QTL population and its parental lines were genotyped using the genotyping-by-sequencing method. A genetic linkage map spanning 2,045.14 cM was constructed using 3,110 SNP markers mapped on 17 sunflower chromosomes. A total of 21 QTL associated with BSR resistance were detected on 11 chromosomes, each explaining a phenotypic variation ranging from 4.5 to 22.6%. Of the 21 QTL, eight were detected for BSR DI measured in the field, seven were detected for traits measured in the greenhouse, and six were detected from both field and greenhouse tests. Thirteen of the 21 QTL had favorable alleles from the H. argophyllus parent conferring increased BSR resistance.

Genomic Insights Into Sclerotinia Basal Stalk Rot Resistance Introgressed From Wild Helianthus praecox Into Cultivated Sunflower (Helianthus annuus L.)

“…Sclerotinia BSR resistance in sunflower is a polygenic trait governed by multiple small effect genes ( Talukder et al, 2014c , 2016 , 2021 ). Quantitative genetic variations for BSR resistance have been mapped in different segregating populations developed from both cultivated and wild sunflower species ( Davar et al, 2010 ; Amouzadeh et al, 2013 ; Talukder et al, 2014c , 2016 , 2021 ; Paknia et al, 2020 ).…”

“…Sclerotinia BSR resistance in sunflower is a polygenic trait governed by multiple small effect genes ( Talukder et al, 2014c , 2016 , 2021 ). Quantitative genetic variations for BSR resistance have been mapped in different segregating populations developed from both cultivated and wild sunflower species ( Davar et al, 2010 ; Amouzadeh et al, 2013 ; Talukder et al, 2014c , 2016 , 2021 ; Paknia et al, 2020 ). In the growth chamber under a controlled environment, Davar et al (2010) identified seven QTL associated with BSR resistance on linkage groups (LGs) 1, 2, 4, 6, 8, 14, and 17 in a recombinant inbred line (RIL) population developed from the cross of PAC1/RHA 266, while Amouzadeh et al (2013) identified five QTL on LGs 1, 3, 8, 10, and 17 in the same population using a different fungal isolate.…”

“…Despite reports of high levels of Sclerotinia resistance existing in the secondary gene-pool, comprehensive studies have not been pursued to characterize and exploit the resistance in practical sunflower breeding programs. Only recently, introgression and molecular mapping of Sclerotinia resistance from wild species have been reported and germplasms with introgressed resistance have been released ( Qi et al, 2016 , 2018 ; Talukder et al, 2019a , b , 2021 ). Talukder et al (2021) mapped 21 BSR resistance QTL in an advanced backcross (AB-QTL) population developed from the cross of HA 89 and an accession of the wild annual species H. argophyllus Torr.…”

“…Only recently, introgression and molecular mapping of Sclerotinia resistance from wild species have been reported and germplasms with introgressed resistance have been released ( Qi et al, 2016 , 2018 ; Talukder et al, 2019a , b , 2021 ). Talukder et al (2021) mapped 21 BSR resistance QTL in an advanced backcross (AB-QTL) population developed from the cross of HA 89 and an accession of the wild annual species H. argophyllus Torr. & Gray (silverleaf sunflower) using a high-density single nucleotide polymorphism (SNP) linkage map.…”

“…The detected QTL were distributed on 11 sunflower chromosomes (LGs 2, 5, 6, 7, 8, 9, 10, 11, 14, 16, and 17) and each QTL explaining between 4.5% and 22.6% of the phenotypic variance. Remarkably, 13 of the 21 QTL had BSR resistance alleles derived from the H. argophyllus parent ( Talukder et al, 2021 ).…”