Grouping of tropical mid-altitude maize inbred lines on the basis of yield data and molecular markers

Abstract

The classification of maize inbred lines into heterotic groups is an important undertaking in hybrid breeding. The objectives of our research were to: (1) separate selected tropical mid-altitude maize inbred lines into heterotic groups based on grain yield data; (2) assess the genetic relationships among these inbred lines using amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers; (3) examine the consistency between yield-based and marker-based groupings of the inbred lines. Thirty-eight tropical mid-altitude maize inbred lines were crossed to two inbred line testers representing the flint and dent heterotic pattern, respectively. The resulting testcrosses were evaluated in a trial at three locations for 2 years. Significant general combining ability (GCA) and specific combining ability (SCA) effects for grain yield were detected among the inbred lines. The tester inbred lines classified 23 of the 38 tested inbred lines into two heterotic groups based on SCA effects and testcross mean grain yields. This grouping was not related to endosperm type of the inbred lines. The outstanding performance of testcrosses of the remaining 15 inbred lines indicates the presence of significant genetic diversity that may allow the assignment of the lines into more than two heterotic groups. Diversity analysis of the 40 maize inbred lines using AFLP and SSR markers found high levels of genetic diversity among these lines and subdivided them into two main groups with subdivision into sub-groups consistent with breeding history, origin and parentage of the lines. However, heterotic groups formed using yield-based combining ability were different from the groups established on the basis of molecular markers. Considering the diversity of the genetic backgrounds of the mid-altitude inbred lines, the marker-based grouping may serve as the basis to design and carry out combining ability studies in the field to establish clearly defined heterotic groups with a greater genetic similarity within groups.

Genetic diversity in elite inbred lines of maize and its association with heterosis

“…The level of polymorphism was similar to those reported by Wiethölter et al (2008), who detected 2.7 alleles per locus in the analysis of 33 microsatellite loci in maize, and Le Clere et al (2005), who analyzed 133 maize cultivars using 51 microsatellite loci and obtained 2.9 alleles per locus on average. In contrast, in the studies by Menkir et al (2004), Adeyemo et al (2011), andTerra et al (2011), the number of alleles ranged from 3.7 to 5.7 per locus. These authors attributed such high polymorphism to the level of divergence found within the genotypes evaluated in conjunction with the pre-selection of the primers that was based on the number and quality of the amplification products.…”

Phylogenetic Relationships Among Teosinte, Maize and Its Hybrids

“…mexicana have statistically significant heterosis compared to the wild teosinte but not when compared to the cultivated parent (Guadagnuolo et al, 2006). Genetic distance GD among the germplasm lines has been quantified by means of morphological, biochemical and molecular analyses and by means of heterosis (Menkir et al, 2004;Laborda et al, 2005). The degree of heterotic effect of F 1 populations correlated with GD of the parental lines, as parents are more divergent, the heterosis is A higher and vice-versa (Prasad and Singh, 1986).…”

Identification of heterotic patterns between expired proprietary, NDSU, and industry short-season maize inbred lines

“…SCA effects and means for grain yield have been widely used to classify maize heterotic groups (Menkir et al 2004, Melani and Carena 2005, Fan et al 2008. Therefore, we used SCA effects and mean grain yield of research trial III to validate heterotic groups of our first set of 12 ex-PVP inbred lines.…”

“…They claimed their way is efficient compared to SSR markers and yield-based specific combining abilities. Menkir et al (2004) classified inbred lines into heterotic groups by yield-based specific combining ability and molecular marker based approaches. They reported that yield-based combining ability derived heterotic groups did not match with groups established using molecular markers.…”