The Production of Helianthus Haploids: A Review of Its Current Status and Future Prospects

Abstract

The genus Helianthus comprises 52 species and 19 subspecies, with the cultivated sunflower (Helianthus annuus L.) representing one of the most important oilseed crops in the world, which is also of value for fodder and technical purposes. Currently, the leading direction in sunflower breeding is to produce highly effective heterosis F1 hybrids with increased resistance to biotic and abiotic stresses. The production of inbred parental lines via repeated self-pollination takes 4–8 years, and the creation of a commercial hybrid can take as long as 10 years. However, the use of doubled haploid technology allows for the obtainment of inbred lines in one generation, shortening the time needed for hybrid production. Moreover, it allows for the introgression of the valuable genes present in the wild Helianthus species into cultivated sunflowers. Additionally, this technology makes it possible to manipulate the ploidy level, thereby restoring fertility in interspecific hybridization. This review systematizes and analyzes the knowledge available thus far about the production of haploid and dihaploid Helianthus plants using male (isolated anther and microspore cultures) and female (unpollinated ovaries and ovules culture) gametophytes, as well as by induced parthenogenesis using γ-irradiated pollen and interspecific hybridization. The genetic, physiological, and physical factors influencing the efficiency of haploid plant production are considered. A special section focuses on the approaches used to double a haploid chromosome set and the direct and indirect methods for determining the ploidy level. The current analyzed data on the successful application of haploid sunflower plants in breeding are summarized.

Accelerated Breeding for Helianthus annuus (Sunflower) through Doubled Haploidy: An Insight on Past and Future Prospects in the Era of Genome Editing

“…The development of haploid embryos through hybridization has been widely achieved in many species, including in a cross between sunflower and the genetically related species, lettuce, for haploid induction in lettuce [ 35 ]. The use of hybridization for haploid induction has not been explored extensively, and no data on sunflower haploid induction through hybridization exist in the literature [ 4 ].…”

“…The majority of these haploid technologies are time consuming, costly, genotype-dependent, and have too low efficiencies to be applied in sunflower breeding [ 23 , 36 ]. Doubled haploid induction methods, such as microspore culture and irradiation of pollen grains, have been tested on sunflower with very little success [ 37 ] and are discussed in detail in the review by Blinkov et al [ 4 ]. Although anther culture [ 27 ] and parthenogenesis [ 26 ] have been partially successful in the induction of haploids in sunflower, they are genotype specific and of limited use [ 4 , 15 , 37 ].…”

“…Doubled haploid induction methods, such as microspore culture and irradiation of pollen grains, have been tested on sunflower with very little success [ 37 ] and are discussed in detail in the review by Blinkov et al [ 4 ]. Although anther culture [ 27 ] and parthenogenesis [ 26 ] have been partially successful in the induction of haploids in sunflower, they are genotype specific and of limited use [ 4 , 15 , 37 ]. These limitations of anther culture and parthenogenesis techniques make them inappropriate for large scale haploid induction, especially since there are numerous genotypes involved in breeding programs.…”

“…Sunflower has great commercial significance on a global scale with a multitude of uses ranging from seed oil and flour for human consumption, oilseed cake for animal feed purposes, raw material for oleo chemistry, to a biofuel feedstock source [ 3 ]. Sunflower production is hindered by numerous biotic challenges, including broomrape, sunflower stem weevil, European sunflower moth, Alternaria leaf spot, downy mildew, verticillium wilt, phomopsis, Sclerotina , and rust [ 4 , 5 , 6 ]. Furthermore, climate change threatens to be accompanied by various limitations to crop production, including unpredictable temperature fluctuations, drought, emergence of novel diseases, and pests [ 7 ].…”

“…True breeding lines can be obtained by repetitive backcrossing to the parental line containing the desirable trait and progeny selection or by developing haploids, with subsequent chromosome doubling to form doubled haploid (DH) lines [ 13 ]. Although sunflower doubled haploids have been previously applied in breeding programs [ 4 ], the absence in sufficiently diverse genetic resources and its recalcitrance to in vitro transformation have been a hindrance in the development of a doubled haploid induction procedure that could be efficiently used in breeding programs [ 14 , 15 ]. As an out-crossing crop, the lack of a double haploid system limits sunflower breeding and associated improvement processes, thereby delaying new trait developments.…”