Utilization of Sunflower Crop Wild Relatives for Cultivated Sunflower Improvement

Abstract

Sunflower (Helianthus annuus L.) is one of the few crops native to the United States. The current USDA–ARS National Plant Germplasm System (NPGS) crop wild relatives sunflower collection is the largest extant collection in the world, containing 2519 accessions comprising 53 species—39 perennial and 14 annual. To fully utilize gene bank collections, however, researchers need more detailed information about the amount and distribution of genetic diversity present within the collection. The wild species are adapted to a wide range of habitats and possess considerable variability for most biotic and abiotic traits. This represents a substantial amount of genetic diversity available for many agronomic traits for cultivated sunflower, which has a very narrow genetic base. Sunflower ranked fifth highest among 13 crops of major importance to global food security surveyed from the mid‐1980s to 2005 in the use of traits from crop wild relatives. The estimated annual economic contribution of the wild species for cultivated sunflower is between US$267 to 384 million. Most of the value is derived from the PET1 cytoplasm from wild H. petiolaris, disease resistance genes, abiotic salt tolerance, and resistance to imidazolinone and sulfonylurea herbicides. Crop wild relatives provide a wide range of valuable attributes for traditional and molecular breeding, as well as for ecological experimentation, and have enabled rapid advances in ecological and evolutionary genetics. The wild species of Helianthus continue to contribute specific traits to combat emerging pests and environmental challenges and, at the same time, are preserved for future generations.

Ancient DNA reveals the timing and persistence of organellar genetic bottlenecks over 3,000 years of sunflower domestication and improvement

“…Overall then, while three organellar genome types predominate in modern cultivated germplasm, these very distinct Class 3 and Class 4 sequences are not shared with landraces, ethnographic, or archaeological samples and have largely entered cultivated H. annuus through recent, deliberate introgression of genetic material from other wild H. species. The history of directed breeding of domesticated sunflower lines with crop wild relatives strongly suggests Class 3 was introduced from H. petolaris during the establishment of the hybrid crop agricultural system (Seiler, Qi, & Marek, ). Class 4 was likely also introduced during crop improvement, potentially from H. argophyllus , the sunflower species which has been most frequently crossed with domesticated lines to impart disease and parasite resistance (Seiler & Fredrick Marek, ).…”

“…As expected based on this breeding history, the mitochondrial haplotype of Class 3 groups closely with sequences present in H. petiolaris (Figure 4). Because only Rf is required to restore fertility in hybrid crop breeding, we do find two R-type cultivars, RHA-418 and RHA-401, (Seiler, Qi, & Marek, 2017).…”

Sustaining the Future of Plant Breeding: The Critical Role of the USDA‐ARS National Plant Germplasm System

“…After a new, more virulent RWA biotype appeared (Haley et al, 2004), another screening was conducted of NPGS materials previously observed to be resistant to the original US biotype of RWA. This screening identified 10 wheat accessions, mostly from Central Asia, that were highly resistant to the new biotype (Collins et al, 2005) (Seiler et al, 2017). In addition, NPGS genebank materials were used to better understand plant architecture and its influences on aspects of plant growth and development, including the genetic basis of variation of branching and its role in crop domestication (Nambeesan et al, 2015).…”

Development of drought‐tolerant breeding lines derived from Helianthus annuus × H. argophyllus interspecific crosses

“…Sunflower wild relatives have been valuable sources for genetic improvement of elite sunflower germplasm (Seiler, Qi, & Marek, ), and have been used to introgress cytoplasmic male sterility, resistance against biotic and abiotic stresses, herbicide resistance and fatty acid modifications (as reviewed in Warburton et al, ). H. argophyllus is a diploid species (2n = 34) and has been exploited for the introgression of fertility restorer genes (Havekes, Miller, & Jan, ), and resistance to rust (Ma, Song, Markell, & Qi, ; Qi et al, ), downy mildew (Ma et al, ), and charcoal rot (Shehbaz et al, ).…”