Molecular mapping of genes for opposite leafing in maize using simple-sequence repeat markers

Area of Science:

• Plant Genetics
• Maize Breeding
• Evolutionary Biology

Background:

• Opposite phyllotaxy (OP) in maize is a rare trait valuable for breeding and evolutionary studies.
• Identifying genes controlling OP is crucial for marker-assisted selection and gene cloning.

Purpose of the Study:

• To map and identify simple sequence repeat (SSR) markers linked to the genes responsible for opposite phyllotaxy in maize.
• To establish a foundation for marker-assisted selection and cloning of the OP genes.

Main Methods:

• Developed a near-isogenic line (H14D) for the OP trait.
• Screened SSR markers for polymorphism between H14D and H53 inbred lines.
• Analyzed linkage between polymorphic SSR markers and the OP trait in an F(2) population (441 progeny).

Main Results:

• The OP trait is controlled by two independent dominant genes, Opp-1 and Opp-2, with complementary action.
• SSR marker umc2094 linked to Opp-1 (6.7 cM) and bnlg1831 linked to Opp-2 (6.1 cM).
• Additional markers bnlg1092 (12.2 cM to Opp-1) and umc1028 (1.9 cM to Opp-2) were identified, flanking both genes.

Conclusions:

• Successfully mapped two major genes (Opp-1 and Opp-2) controlling opposite phyllotaxy in maize.
• Identified four SSR markers flanking these genes, facilitating marker-assisted selection in maize breeding.
• Provided essential data for the future cloning of the genes responsible for opposite leaf arrangement in maize.