Genetic diversity of maize inbred lines and heterosis

Abstract

The genetic diversity of six maize inbred lines, as well as, the genetic similarity between parental inbred lines and heterosis for yield in their F1 crosses was studied. Three inbred lines (ZPL 142, ZPL 680 and ZPL 357/3) are of the BSSS origin and another three (ZPL 257/3, ZPL 17/5 and ZPL 173/3) are of the non-BSSS genetic background. Molecular markers provide a direct determination of a number for which two inbred lines are different for a given number of loci. Maize inbred lines were genetically characterized with RAPD markers. Genetic similarity among genotypes was done by a statistical analysis with NTSYSpc v2.0 and by the application of the cluster analysis. Parental inbred lines, 30 F1 crosses with reciprocals, were included in a randomized complete block design with four replications in two densities (44,640 and 64,935 plants ha-1) at the location of Zemun Polje in 2003 and 2004. The differences among genotypes (F1 and inbreds line per se), densities and years were statistically significant. The highest value of mid-parent heterosis (192.2 %), as well as, the best-parent heterosis (178.0 %) was obtained for the cross ZPL 173/3 x ZPL 680 over investigated densities and years. The Spearman's correlation coefficient was used to determine correlations between the values of heterosis obtained in the field experiment and the value of genetic distances based on RAPD markers. The obtained results indicate that RAPD markers can be used to study the genetic diversity of maize inbred lines, although their application in the prediction of heterosis for grain yield is limited.

U radu je ispitivana genetička različitost šest samooplodnih linija kukuruza na osnovu RAPD markera i odnos genetičke sličnosti između roditeljskih linija i heterozisa za prinos zrna u njihovim ukrštanjima (F1 hibridima). Roditeljske linije i 30 F1 hibrida, dobijenih ukrštanjem roditeljskih linija u potpunom dijalelu, su testirani po slučajnom blok dizajnu sa četiri ponavljanja u dve gustine useva (G1=44.640 i G2=64.935 biljaka ha-1) u Zemun Polju tokom 2003 i 2004. godine. Razlike u prinosu zrna između ispitivanih genotipova (F1 i samooplodne linije per se), ispitivanih gustina i spoljnih sredina su bile statistički značajne. Najveći heterozis dobijen je kod kombinacije ZPL 173/3 x ZPL 680 i u odnosu na vrednost srednjeg roditelja (192.2 %) i u odnosu na boljeg roditelja (178.0 %) u ispitivanim gustinama i godinama. Za određivanje korelacija između vrednosti za heterozis u kombinacijama dobijenim u poljskom ogledu i vrednosti genetičkih distanci izračunatih na osnovu RAPD markera korišćen je Spearman-ov koeficijent korelacije. Dobijeni rezultati ukazuju da se RAPD markeri mogu koristiti za ispitivanje genetičke divergentnosti samooplodnih linija kukuruza, mada je njihova primena za predviđanje heterozisa za prinos zrna ograničena.