Inheritance and molecular markers for aphid (Macrosiphoniella sanbourni) resistance in chrysanthemum (Chrysanthemum morifolium Ramat.)

• The inheritance and molecular markers were first investigated for aphid resistance in chrysanthemum.
• Aphid resistance was controlled with two pairs of major genes with additivity and high heritability.
• Useful markers were detected for aphid resistance with marker-trait analysis, BSA, and QTL mapping.
• The findings would facilitate MAS for aphid resistance in future.

Aphids have caused great damage to chrysanthemum production, and it's crucial to breed new chrysanthemums with strong aphid resistance. However, little information is available regarding the inheritance of aphid resistance in chrysanthemum. The inheritance pattern of chrysanthemum aphid resistance within an F1 segregating population was dissected with the major gene plus polygene mixed inheritance model and molecular markers. The result showed that aphid resistance of chrysanthemum is a quantitative trait with a moderate coefficient of variation >50%. The mixed inheritance model based on a single segregating generation suggested the inheritance of aphid resistance was controlled by two pairs of major genes with additive effect 0.68 and 0.39, respectively. The heritability of major gene was calculated at 89.21%. Marker-trait analysis based on one-way variance analysis uncovered 11 markers significantly associated with phenotype, cumulatively explaining ∼74% variation. Bulked segregant analysis (BSA) based on the gene bulks of high resistant and susceptive genotypes in F1 population identified two SSR markers, SSR145-93 and SSR197-205, linked to high aphid resistance (r > 0.4). The QTL analysis detected 5 putative QTL for aphid resistance in two successive years, with individual QTL explaining the phenotypic variation of 14.30–28.00%. The inheritance model and molecular markers identified for aphid resistance facilitate the ongoing breeding activities in chrysanthemum.