African Journal of Agricultural Research Vol. 6(3), pp. 630-635, 4 February, 2011 Available online at http://www.academicjournals.org/AJAR DOI: 10.5897/AJAR10.460 ISSN 1991-637X ©2011 Academic Journals Full Length Research Paper Genetic analysis of resistance to common smut in maize (Zea mays L.) using triple test cross Anita Namayandeh 1 *, Rajab Choukan 2 , Seyed Abolghasem Mohahhadi 3 , Mohammad Mojtaba Kamelmanesh 4 , Sasan Ghasemi 4 , and Eslam Majidi Hervan 1 1 Science and Research Branch, Islamic Azad University (IAU), Tehran, Iran 2 Seed and Plant Improvement Institute, Karaj, Iran. 3 Department of Agronomy and Plant Breeding, University of Tabriz, Tabriz, Iran. 4 Islamic Azad University Shiraz Branch, Shiraz, Iran. Accepted 2 July, 2010 Understanding of gene action for resistance to maize common smut is essential for maize breeding programs, therefore, triple test cross analysis was employed to assess gene action controlling resistance to common smut in maize. Parental inbred lines and their progenies were evaluated using randomized complete block design with three replications in Karaj Field Station, Seed and Plant Improvement Institute, in 2007 and 2008 cropping seasons. Epistasis was observed for resistance to maize common smut. Partitioning of the total epistasis revealed that [i] type (additive × additive) and [I+J] types (additive × dominance and dominance × dominance) were highly significant. Additive (L 1i +L 2i ) and dominance (L 1i – L 2i ) effects for resistance to maize common smut were also significant, over two growing seasons. Dominance ratio (H/D) 1/2 indicated that resistance to maize common smut was controlled by dominance effect. However, the direction of dominance (r s,d ) for this character in two growing seasons was not-significant which implies that dominant alleles were distributed in parents, therefore they did not express any directional dominance for this attribute. Since F′ was positive, therefore, dominant alleles increased disease severity of maize common smut. Cytoplasmic effects were also important for resistance to maize common smut. Combined analysis of variance showed that the effect of year and genotype × year interaction were highly significant. Generally, the additive, dominance and epistatic components were important in resistance to maize common smut. It is concluded that Genetic analysis of Resistance to Common Smut in Maize (Zea mays L.) using triple test cross recurrent selection procedure may be efficient in breeding for resistant to maize common smut, since it exploits additive and non-additive components of genetic variation for improvement resistance to maize common smut. Key words: Zea mays, triple test cross, common smut, gene action. INTRODUCTION Common smut caused by Ustilago maydis, is one of the most serious diseases that occurs in maize growing areas throughout the world. Like many economically important plant-pathogen systems, breeding for genetic resistance in the host, is the most effective way to control common smut (Du Toit and Pataky, 1999). Employing an effective breeding procedure depends to a large extent *Corresponding author. E-mail: anitanamayandeh@yahoo.com, anm@iaushiraz.ac.ir. Tel: +989173028464. Fax: +987112342050, +987112342019. on understanding of the genetic mechanisms controlling the characters to be improved (Sadat Noori and Sokhansany, 2004). Resistance to maize common smut and the nature of the host-pathogen interaction are still method of inoculation (Pataky et al., 1995). Hence, only limited molecular genetic information is available on inheritance of resistance to common smut in maize. Various quantitative genetic approaches have been used for estimating the mode of gene action in controlling resistance to common smut disease in maize. Most of the genetic design used to analyze mode of gene action assume absence of non-allelic interactions, however, there are contrary evidences to this assumption (Ashfa et