Heterotic groups in tropical maize germplasm by test crosses and simple sequence repeat markers

Area of Science:

• Agricultural Science
• Plant Breeding
• Genetics

Background:

• Identifying heterotic groups is crucial for hybrid breeding programs in tropical maize.
• Traditional methods using test crosses can be time-consuming and resource-intensive.

Purpose of the Study:

• To determine heterotic groups of tropical maize germplasm lines.
• To compare five different grouping methods, including test crosses and simple sequence repeat (SSR) markers.
• To evaluate the efficacy of genetic diversity metrics and SSR markers in classifying maize lines.

Main Methods:

• Evaluated 16 S5 generation maize lines from nine populations via test crosses with three testers.
• Applied five grouping methods: hybrid mean, hybrid index, Mahalanobis distance, Euclidean distance, and SSR markers.
• Analyzed data from four experimental trials conducted over two years.

Main Results:

• High concordance (87.50%) was observed between Mahalanobis and Euclidean distance grouping methods.
• Moderate concordance (56.25%) was found between distance-based methods and SSR marker grouping.
• Grouping by SSR markers demonstrated consistency with the known genealogy of the maize lines.

Conclusions:

• Simple sequence repeat (SSR) markers provide a reliable and consistent method for grouping tropical maize lines.
• SSR marker analysis is a valuable tool for forming effective heterotic groups in maize breeding.
• This approach can complement or potentially replace traditional test cross evaluations for heterotic grouping.