Abstract
Adequate knowledge and understanding of the genetic diversity and inter-trait relationships among elite maize inbred lines are crucial for determining breeding strategies and predicting hybrid performance. The objectives of this study were to investigate the genetic diversity of 162 early maturing white and yellow tropical maize inbred lines, and to determine the population structure, heterotic groups and inter-trait relationships among the lines. Using 9684 DArT single nucleotide polymorphism (SNP) markers, a gene diversity (GD) of 0.30 was recorded for the inbred lines with polymorphic information content (PIC) ranging from 0.08 to 0.38. The genetic relatedness among the inbred lines evaluated revealed six different groups based on the history of selection, colour of endosperm and pedigree. The genotype-by-trait (GT) biplot analysis identified inbred 1 (TZEI 935) as outstanding in terms of combined heat and drought (HD) tolerance with the base index analysis identifying 15 superior inbreds in the HD environment. A wide range of genetic variability was observed among the inbred lines, indicating that they are an invaluable resource for breeding for HD tolerance in maize breeding programmes, especially in West and Central Africa.
Highlights
Molecular analyses in combination with morphological and agronomic evaluation of germplasm are useful for providing complementary information on the genetic diversity in a breeding programme [1]
The results revealed that the sector with inbreds 21 and 8 as the vertex inbreds contained the traits Leaf death (LD), tassel blasting (TB), LF, anthesis–silking interval (ASI), husk cover (HUSKC), SL, EASP and plant aspect (PLASP), indicating that these inbreds had high values for these traits and that they were the low-yielding inbreds based on the high values of these traits
The population structure analysis, Principal Coordinate Analysis (PCoA) and phylogenetic clustering methods confirmed the existence of six different groups for the panel of 162 maize inbred lines studied
Summary
Molecular analyses in combination with morphological and agronomic evaluation of germplasm are useful for providing complementary information on the genetic diversity in a breeding programme [1]. Monitoring of genetic diversity in the base material helps breeders to formulate breeding strategies by selecting parental combinations for advance selection [2], determining the level of genetic variability whilst identifying the main clusters selected for specific traits [3]. Information on genetic diversity is useful in classifying inbred lines into heterotic groups [4,5], and predicting hybrid performance [6]. Molecular marker technology has been a resourceful technique for assessing genetic diversity and delimiting heterotic groups [11]
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