Genetic distance estimated by RAPD markers and its relationship with hybrid performance in maize

Daniela Cristina Bruel,Cássio Egídio Cavenaghi Prete,Claudete De Fátima Ruas,Valéria Carpentieri-Pípolo,Antonio Carlos Gerage,Paulo Maurício Ruas,Nelson Da Silva Fonseca Júnior,Silvia Graciele Hülse De Souza,Deoclécio Domingos Garbuglio

doi:10.1590/s0100-204x2006001000006

Abstract

The objective of this work was to evaluate the genetic diversity of 16 maize inbred lines, and to determine the correlation between genetic distance and hybrid performance, using random amplified polymorphic DNA (RAPD) molecular markers. Twenty-two different random primers were used, which resulted in the amplification of 265 fragments, 237 (84.44%) of them being polymorphic. A genetic similarity matrix was created from the RAPD data, using Jaccard coefficient, and a dendrogram was constructed. Hybrid analyses were carried out using random block design and Griffing method VI for diallel crossings. The genetic associations showed five distinct heterotic groups. Correlations between genetic divergences detected by RAPD, as well as the means observed in the diallel crossings were positive and significant for plant height, ear height, prolificacy, and grain weight. The correlation of genetic divergences, detected by RAPD, and the specific combining ability between heterotic group associations, showed significance in all characteristics under study, except prolificacy. A direct relationship between genetic divergence and productivity was found in 79.2% of the 120 hybrids confirming the hypothesis that genetic divergence is directly related to the performance of hybrids and is efficient in predicting it.

Highlights

The maize hybrid development within a breeding program consists in obtaining lines and evaluating their combining ability
From the genetic breeding program of Instituto Agronômico do Paraná (IAPAR), were used, belonging to five heterotic groups (Table 1): group A: L69 – line obtained by self-fertilization from the IPTT36 population introduced by CIMMYT (Centro Internacional de Mejoramiento de Maíz y Trigo, Mexico); Group B: L72 – line obtained by self-fertilization from a commercial triple hybrid; Group C: L89, L90, L91, L92, L93, and L94 – lines obtained by self-fertilization from a commercial single hybrid; Group D: L95, L96, L97, L98, L99, L100, and L101 – lines obtained by self-fertilization from an experimental single hybrid from IAPAR; and Group E: L102 – lineobtainedbyself-fertilizationwithintheAmarilloCristalino variety from CIMMYT
Five morphological characters were evaluated: female flowering (FF) – period elapsed from emergence to silk emission; plant height (PH) – measure from the soil surface to the flag leaf curvature; ear height (EH) – measure from the soil surface to the insertion point of the highest ear; prolificacy (PROL) – determined by the ratio between numbers of ears/final stand; grain yield (GY) – adjusted to kg ha-1, with a moisture degree corrected to 14.5%, based on the grain yield obtained from all ears harvested in the plot

Summary

Introduction

The maize hybrid development within a breeding program consists in obtaining lines and evaluating their combining ability. One of the most important decision that breeders have to make refers to the selection of populations for a breeding program. This decision must be as correct as possible, since a bad choice will imply on a waste of breeding time and resources. Genetic diversity evaluation is frequently used by maize breeders as an alternative method for germplasm selection. The aim of this method is to select more promising materials and to decrease expenditures and. Efforts are focused on more promising combinations, that is, those between more divergent materials

Objectives

Methods

Results

Conclusion