Fakude Mercy, Murithi Ann, Frei Ursula K, Scott Paul M, Lübberstedt Thomas
Department of Agronomy, Iowa State University, Ames, IA, 50011, USA.
United States Department of Agriculture, Agricultural Research Service, Corn Insects and Crop Genetics Research Unit, Ames, IA, 50011, USA.
Theor Appl Genet. 2024 Dec 11;138(1):5. doi: 10.1007/s00122-024-04789-5.
Restoration of haploid female and haploid male fertility without colchicine is feasible. Three SNPs and eight gene models for HFF, and one SNP and a gene model for HMF were identified. Doubled haploid (DH) breeding accelerates the development of elite inbred lines and facilitates the incorporation of exotic germplasm, offering a powerful tool for maize improvement. Traditional DH breeding relies on colchicine to induce haploid genome doubling. Colchicine is toxic, and its application is labor-intensive, with most genotypes recording low genome doubling rates (10-30%). This study investigates spontaneous haploid genome doubling (SHGD) as a safer and more efficient alternative to colchicine. We evaluated the effectiveness of SHGD in restoring haploid female fertility (HFF) and haploid male fertility (HMF) without colchicine. Using genome-wide association studies (GWAS), we identified genomic regions influencing HFF and HMF. The plant materials included the BS39-haploid isogenic lines (HILs) and BS39-SHGD-haploid isogenic lines (HILs). Our results revealed significant SNP associations for both traits, with candidate genes involved in cell cycle regulation, cytoskeletal organization, and hormonal signaling. Analysis of variance (ANOVA) revealed significant variation in HFF across haploids and two environments. Similarly, HMF showed substantial differences across haploids and between the two environments. Spearman correlation between HFF and HMF showed no correlation (r = -0.03) between the two traits. HFF showed high heritability (0.8), indicating strong genetic control, whereas HMF displayed moderate heritability (0.5), suggesting additional environmental influences. The findings underscore the potential of SHGD to enhance DH breeding efficiency and support the development of new maize varieties tailored to diverse agricultural needs.
不使用秋水仙碱恢复单倍体雌株和单倍体雄株育性是可行的。鉴定出了3个与单倍体雌株育性相关的单核苷酸多态性（SNP）和8个基因模型，以及1个与单倍体雄株育性相关的SNP和1个基因模型。双单倍体（DH）育种加速了优良自交系的培育，并促进了外来种质的导入，为玉米改良提供了有力工具。传统的DH育种依靠秋水仙碱诱导单倍体基因组加倍。秋水仙碱有毒，其应用劳动强度大，大多数基因型的基因组加倍率较低（10%-30%）。本研究调查了自发单倍体基因组加倍（SHGD）作为秋水仙碱更安全、更有效的替代方法。我们评估了SHGD在不使用秋水仙碱的情况下恢复单倍体雌株育性（HFF）和单倍体雄株育性（HMF）的有效性。利用全基因组关联研究（GWAS），我们鉴定出了影响HFF和HMF的基因组区域。植物材料包括BS39-单倍体同基因系（HILs）和BS39-SHGD-单倍体同基因系（HILs）。我们的结果揭示了这两个性状的显著SNP关联，候选基因涉及细胞周期调控、细胞骨架组织和激素信号传导。方差分析（ANOVA）显示，单倍体和两种环境下的HFF存在显著差异。同样，HMF在单倍体之间和两种环境之间也表现出显著差异。HFF和HMF之间的Spearman相关性显示这两个性状之间无相关性（r = -0.03）。HFF表现出高遗传力（0.8），表明有较强的遗传控制，而HMF表现出中等遗传力（0.5），表明有额外的环境影响。这些发现强调了SHGD提高DH育种效率的潜力，并支持开发适应不同农业需求的新玉米品种。
