Genotyping-by-Sequencing Uncovers the Introgression Alien Segments Associated with Sclerotinia Basal Stalk Rot Resistance from Wild Species—I. Helianthus argophyllus and H. petiolaris

Abstract

Basal stalk rot (BSR), caused by Sclerotinia sclerotiorum, is a devastating disease in sunflower worldwide. The progress of breeding for Sclerotinia BSR resistance has been hampered due to the lack of effective sources of resistance for cultivated sunflower. Our objective was to transfer BSR resistance from wild annual Helianthus species into cultivated sunflower and identify the introgressed alien segments associated with BSR resistance using a genotyping-by-sequencing (GBS) approach. The initial crosses were made between the nuclear male sterile HA 89 with the BSR resistant plants selected from wild Helianthus argophyllus and H. petiolaris populations in 2009. The selected resistant F1 plants were backcrossed to HA 458 and HA 89, respectively. Early generation evaluations of BSR resistance were conducted in the greenhouse, while the BC2F3 and subsequent generations were evaluated in the inoculated field nurseries. Eight introgression lines; six from H. argophyllus (H.arg 1 to H.arg 6), and two from H. petiolaris (H.pet 1 and H.pet 2), were selected. These lines consistently showed high levels of BSR resistance across seven environments from 2012 to 2015 in North Dakota and Minnesota, USA. The mean BSR disease incidence (DI) for H.arg 1 to H.arg 6, H.pet 1, and H.pet 2 was 3.0, 3.2, 0.8, 7.2, 7.7, 1.9, 2.5, and 4.4%, compared to a mean DI of 36.1% for Cargill 270 (susceptible hybrid), 31.0% for HA 89 (recurrent parent), 19.5% for HA 441 (resistant inbred), and 11.6% for Croplan 305 (resistant hybrid). Genotyping of the highly BSR resistant introgression lines using GBS revealed the presence of the H. argophyllus segments in linkage groups (LGs) 3, 8, 9, 10, and 11 of the sunflower genome, and the H. petiolaris segments only in LG8. The shared polymorphic SNP loci in the introgression lines were detected in LGs 8, 9, 10, and 11, indicating the common introgression regions potentially associated with BSR resistance. Additionally, a downy mildew resistance gene, Pl17, derived from one of the parents, HA 458, was integrated into five introgression lines. Germplasms combining resistance to Sclerotinia BSR and downy mildew represent a valuable genetic source for sunflower breeding to combat these two destructive diseases.

Gene banks for wild and cultivated sunflower genetic resources

“…Many of USDA's activities are continuation of previous uses of CWR, mostly centred on diversification of sources of resistance to disease. Introgressions from H. praecox, H. argophyllus, and H. petiolaris have been associated with Sclerotinia basal stalk rot resistance (Qi et al, 2016;Talukderet al, 2019) and were combined with downy mildew (caused by Plasmopara halstedii) resistance previously recovered from the primary CWR (Hulke et al, 2010). Similar work in diversification of downy mildew resistance sources has come from the secondary CWR pool, as well, with the independent genes Pl18, Pl20, and Pl35 recently introgressed from H. argophyllus (Qi et al, 2019).…”

Registration of Oilseed Sunflower Germplasms HA‐BSR2, HA‐BSR3, HA‐BSR4, and HA‐BSR5 with Resistance to Sclerotinia Basal Stalk Rot and Downy Mildew

“…Quantitative trait loci (QTL) mapping of partial BSR resistance in the cultivated sunflower indicated that the resistance is controlled by multi‐genes with additive effects (Davar et al, 2010; Amouzadeh et al, 2013; Talukder et al, 2016). This was also the case for the wild species where introgressed alien segments were detected in several chromosomes in the BSR‐resistant lines revealed by genotyping‐by‐sequencing (Qi et al, 2016b).…”

“…Sclerotinia BSR evaluations of the early generations of F 1 through BC 2 F 2 were performed in the greenhouse under controlled conditions during winter and early spring as described by Qi et al (2016b). In the BC 2 F 2 generation, 11 BSR‐resistant BC 2 F 3 families were selected from 768 BC 2 F 2 plants of the cross NMSHA 89/ H. petiolaris PI 435843, and 20 BSR resistant BC 2 F 3 families were selected from 644 BC 2 F 2 plants of the cross NMSHA 89/ H. argophyllus PI 494573 from greenhouse tests in winter 2011.…”

“…Genetic analysis using a genotyping‐by‐sequencing approach revealed the presence of introgressed alien segments in HA‐BSR2 located on linkage group (LG) 8, HA‐BSR3 on LGs 8, 9, 10, and 11, HA‐BSR4 on LGs 8 and 10, and HA‐BSR5 on LGs 3 and 10 (Qi et al, 2016b). HA‐BSR3, HA‐BSR4, and HA‐BSR5 likely carry different H. argophyllus segments that are associated with BSR resistance.…”

Molecular advances on agricultural crop improvement to meet current cultivating demands

“…Alternative transgenic methods have been developed to reinforce sunfl ower resistance to diseases. A number of homologues resistance (R) gene have been isolated from sunfl ower, providing a valuable resource for engineering disease resistance in sunfl ower (Dimitrijevic and Horn 2018;Hewezi et al, 2006;Qi et al, 2016;Talukder et al, 2016).…”