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

Abstract

The aim of any breeding process is to fully express the targeted, superior/desirable parent characteristic in the progeny. Hybrids are often used in this dynamic, and complex process for which homozygous parents—which may require up to eight generations of back crossing and selection—are required. Doubled haploid (DH) technologies can facilitate the production of true breeding lines faster and in a more efficient manner than the traditional back crossing and selection strategies. Sunflower is the third most important oilseed crop in the world and has no available double haploid induction procedure/technique that can be efficiently used in breeding programs. A reproducible and efficient doubled haploid induction method would be a valuable tool in accelerating the breeding of new elite sunflower varieties. Although several attempts have been made, the establishment of a sunflower doubled haploid induction protocol has remained a challenge owing recalcitrance to in vitro culture regeneration. Approaches for haploid development in other crops are often cultivar specific, difficult to reproduce, and rely on available tissue culture protocols—which on their own are also cultivar and/or species specific. As an out-crossing crop, the lack of a double haploid system limits sunflower breeding and associated improvement processes, thereby delaying new hybrid and trait developments. Significant molecular advances targeting genes, such as the centromeric histone 3 (CenH3) and Matrilineal (MTL) gene with CRISPR/Cas9, and the successful use of viral vectors for the delivery of CRISPR/Cas9 components into plant cells eliminating the in vitro culture bottleneck, have the potential to improve double haploid technology in sunflower. In this review, the different strategies, their challenges, and opportunities for achieving doubled haploids in sunflower are explored.

Genomics-assisted speed breeding for crop improvement: present and future

“…To speed up the creation of new, superior sunflower parental lines, a reliable and effective doubled haploid (DH) induction technique would be a useful resource. However, there are a lot of obstacles to creating a successful protocol, such as sunflower's resistance to in vitro culture regeneration as well as long fresh seed dormancy, which creates a production bottleneck for DH (Miladinović et al, 2019;Mabuza et al, 2023). Several techniques, including anther culture, microspore culture, interspecific hybridization, and embryo rescue, have been used to create a sunflower DH induction regimen, but none of them have proven effective or dependable.…”

“…Several techniques, including anther culture, microspore culture, interspecific hybridization, and embryo rescue, have been used to create a sunflower DH induction regimen, but none of them have proven effective or dependable. Low crossability, low seed set, low germination and regeneration, and a high albinism rate are the primary obstacles (Kaya, 2014;Mabuza et al, 2023). As a result, different strategies are required to get over these restrictions and raise the production efficiency of sunflower DH.…”

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“…One of the most important oilseed crops, known to humanity for centuries, is the sunflower [34][35][36][37]. Market leaders in sunflower production are countries from Europe and Asia.…”

Induction of haploid plants for speed-up breedıng in sunflower (Helianthus annuus L.) by pollen irradiation

“…It is necessary to generate varieties with desirable traits as well as sustainable agricultural growth and economic activities for breeders. Doubled haploid (DH) technology, as opposed to conventional backcrossing and selection methods, can speed up and improve the efficiency of the development of true breeding lines (Mabuza et al, 2023). Obtaining haploids has several advantages for the advancement of genetic studies, particularly in foreign pollination plants where there is no available DH induction procedure/technique that can be efficiently used in breeding programs.…”