Genetic diversity analysis and heterotic grouping of Indian white maize inbred lines using combining ability and SNP markers

Maize (Zea mays L.) is a versatile crop with high genetic yield potential and various uses. While yellow maize is primarily used for animal feed, white maize is preferred as a food by rural and tribal populations in India. However, white maize landraces suffer immensely in terms of low yield. Heterotic grouping is an excellent method to develop hybrids with increased yield potential in maize. The heterotic grouping of 78 white maize inbred lines was performed using combining ability and molecular diversity analysis. The lines were crossed with two testers, and the resulting hybrids were evaluated for grain yield at three locations representing different agroecological zones in India. The combining ability analysis based on specific combining ability effects on mean grain yield was used to classify the inbred lines into heterotic groups (HG-A: 18 inbreds; HG-B: 33 inbreds). Additionally, marker-based clustering using 62,470 single nucleotide polymorphisms (SNPs) generated through genotyping by sequencing was also employed to determine the genetic relationships among these lines. The combining ability information was superimposed on marker-based clustering data to obtain the heterotic grouping information, and two distinct HGs with 7 (HG-1) and 18 inbred lines (HG-2) were developed. The results of this study will contribute to the development of high-performing white maize hybrids through the efficient utilization of clear-cut and well-defined HGs. Hence, the use of SNP markers along with the combining ability of inbred lines is a useful method for heterotic grouping and understanding of genetic relationships of white maize. White maize is a staple crop in many parts of the world, but resources are mostly devoted in yellow maize in India. The establishment of heterotic groups in white maize is important for developing high-yielding hybrids. The current study uses both combining ability and single nucleotide polymorphism (SNP)-based methods for efficiently grouping the maize inbred lines.