Phenotypic and Genetic Dissection of Maize Internode Length

Plant height is among the most studied traits in maize, and is a function of two component traits, internode length and node number which is associated with flowering time. With the growing interest in utilizing maize as a source of biomass for biofuel production, it is desirable to alter the maize ideotype to enhance not only grain yield but also biomass yield without altering maturity. This could be achieved through the development of plants with superior plant height. The objectives of this study were to characterize the phenotypic diversity, determine the relationships among plant height and internode length, and map quantitative trait loci (QTL) for these traits using two recombinant inbred line populations and two association panels. Our results indicate that plant height can be phenotypically and genetically dissected into node number and internode length, but variation in lengths of individual internodes makes internode length less heritable than node number. Internode length below the uppermost ear showed a strong association with plant height and internode length, but was weakly correlated with node number and flowering time. Plant height, node number, and flowering time were moderately correlated to each other. Several QTL and single nucleotide polymorphisms were associated with internode length below the uppermost ear. QTL-hotspots were identified for plant height, internode length, and internode length below the uppermost ear. This study constitutes an important step towards the characterization of the genetic architecture of internode length, a key trait in maize breeding and genetics.