Genetic analysis and identification of genomic regions associated with ear placement in subtropical maize (Zea mays)

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Abstract The genetic studies of ear height and its related traits were carried out by making crosses between two contrasting parents for ear placement i.e. , AKON 40A (high) and LM 23 (low) to generate F 1 hybrids, which were selfed to produce F 2 population and backcrossed with both parents to generate BC 1.1 and BC 1.2 generations. Generation mean analysis was performed on all six generations for a total of 12 morphological and phenological traits. The genetic components revealed the presence of additive gene action, additive × additive and additive × dominance gene interaction for ear placement and plant height. To map the QTLs/genes for ear placement a total of 284 SSR primer pairs were applied, 146 primer pairs confirmed parental polymorphism, while nine primers exhibited polymorphism in bulked segregant analysis (BSA). These nine primers were used for constructing linkage map in F 2 population. Three linkage groups were identified in which LG 1 spanned 26.9 cM on chromosome 3 while, LG 2 and LG 3 spanned 42.1 and 6.7 cM on chromosome 6 and 7, respectively. Genomic region influencing ear placement was mapped on chromosome 6 between the SSR primers umc1979 and umc2317 having LOD value of ~3 and the phenotypic variance (R 2 ) of 8.5. The prevalence of additive gene action for ear height suggested that recurrent selection can be utilized to improve source population for reducing ear placement by accumulating favourable alleles. Improved source population then can be utilized for inbred line development leading to maize hybrids having medium to low ear placement.

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