Cromie Juliana, Cullen Ryan P, Azevedo Camila Ferreira, Ferrão Luis Felipe V, Enciso-Rodriguez Felix, Benevenuto Juliana, Muñoz Patricio R
Blueberry Breeding and Genomics Laboratory, Horticultural Sciences Department, University of Florida, 2560 Hull Rd, Gainesville, FL 32611, USA.
Statistics Department, Federal University of Viçosa, Av. Peter Henry Rolfs, s/n, Viçosa, MG 36570-900, Brazil.
Hortic Res. 2025 Mar 21;12(7):uhaf086. doi: 10.1093/hr/uhaf086. eCollection 2025 Jul.
Parthenocarpy is a desirable trait that enables fruit set in the absence of fertilization. While blueberries typically depend on pollination for optimal yield, certain genotypes can produce seedless fruits through facultative parthenocarpy, eliminating the need for pollination. However, the development of parthenocarpic cultivars has remained limited by the challenge of evaluating large breeding populations. Thus, establishing molecular breeding tools can greatly accelerate genetic gain for this trait. In the present study, we evaluated two blueberry breeding populations for parthenocarpic fruit set and performed genome-wide association studies (GWAS) to identify markers and candidate genes associated with parthenocarpy. We also compared the predictive ability (PA) of three molecular breeding approaches, including (i) genomic selection (GS); (ii) GS GWAS (GSGWAS), which incorporates significant GWAS markers into the GS model as prior information; and (iii) marker-assisted selection (MAS), where markers from GWAS were fitted as fixed effects with no additional marker information. GWAS analyses identified 55 marker-trait associations, revealing candidate genes related to phytohormones, cell cycle regulation, and seed development. Predictive analysis showed that GSGWAS consistently outperformed GS and MAS, with PAs ranging from 0.21 to 0.36 depending on the population of study and the specific markers utilized. MAS showed PAs comparable to GS in some cases, suggesting it could be a cost-effective alternative to genome-wide sequencing. Together, these findings demonstrate that molecular breeding techniques can be used to improve facultative parthenocarpy, offering new avenues to develop high-yielding blueberry varieties that are less reliant on pollination.
单性结实是一种理想的性状，可使果实无需受精就能结实。虽然蓝莓通常依赖授粉来实现最佳产量，但某些基因型可以通过兼性单性结实产生无籽果实，从而无需授粉。然而，由于评估大量育种群体面临挑战，单性结实品种的开发仍然有限。因此，建立分子育种工具可以大大加快这一性状的遗传增益。在本研究中，我们评估了两个蓝莓育种群体的单性结实情况，并进行了全基因组关联研究（GWAS），以确定与单性结实相关的标记和候选基因。我们还比较了三种分子育种方法的预测能力（PA），包括（i）基因组选择（GS）；（ii）GS+GWAS（GSGWAS），即将显著的GWAS标记作为先验信息纳入GS模型；以及（iii）标记辅助选择（MAS），其中将来自GWAS的标记作为固定效应进行拟合，不使用额外的标记信息。GWAS分析确定了55个标记-性状关联，揭示了与植物激素、细胞周期调控和种子发育相关的候选基因。预测分析表明，GSGWAS始终优于GS和MAS，其PA值根据研究群体和所使用的特定标记在0.21至0.36之间。在某些情况下，MAS的PA值与GS相当，这表明它可能是全基因组测序的一种经济有效的替代方法。总之，这些发现表明分子育种技术可用于改善兼性单性结实，为培育产量高且对授粉依赖较小的蓝莓品种提供了新途径。
