Combining Ability and Gene Action Estimates of Eight Parent Diallel Crosses of Chickpea for Ascochyta Blight

Mohamed Labdi,Samia Hamdi,Samia Ghomari

doi:10.1155/2015/832597

Abstract

Ascochyta blight resistance was studied in half-diallel cross involving eight genotypes of chickpea at seedling and adult stages. The disease was rated in the greenhouse with a modified scale from 0 to 100%. The diallel analysis was performed on 28 F1 and their F2. The results were analyzed with the Hayman and Griffing methods. The general combining ability is most important for two generations, is highly significant for the two stages, and is more important than specific combining ability. This result reflects a strong preponderance of additive effects and epistasis additive × additive with respect to dominance effects in this material for the two generations, which shows the predominance of additive versus dominance. Estimates of heritability are very high. The additive effects have the highest value indicating the importance of this component for resistance toAscochyta. For seedling stage, the negative sign of F for both generations indicates that there are much more recessive alleles that affect resistance to the disease. In adult stage, F is positive in both generations and shows more dominant alleles that control plant reaction to pathogen. H2is positive in both generations which show that dominant genes are acting mostly towards the susceptibility.

Highlights

Ascochyta blight caused by Ascochyta rabiei (Pass.) Labr. is a devastating disease of chickpea (Cicer arietinum L.) in most of the chickpea-producing countries in the Mediterranean region
(1) For the seedling stage the lines are divided into three groups significantly different: (i) susceptible lines: ILC 263 and ILC 605, (ii) moderately susceptible line: ICC 12004, (iii) resistant lines: ILC 8068, ICC 4475, ILC 200, ILC 7374, and ILC 7795
(2) For the adult stage, the lines are divided only in two different groups: (i) susceptible lines: ICC 12004, ILC 263, ILC 605, and ICC 4475, (ii) resistant lines: ILC 8068, ILC 7374, ILC 7795, and ILC 200. It appears that the lines ICC 12004 and ICC 4475 are moderately susceptible to resistant in the seedling stage and became completely susceptible in the adult stage

Summary

Introduction

Ascochyta blight caused by Ascochyta rabiei (Pass.) Labr. is a devastating disease of chickpea (Cicer arietinum L.) in most of the chickpea-producing countries in the Mediterranean region. Ascochyta blight caused by Ascochyta rabiei (Pass.) Labr. In Algeria when the conditions are favorable for the development of the disease, the yield is decreasing drastically (10 to 80% of losses). Sometimes it may cause failure of the whole chickpea crop. Current cultivars only possess partial resistance to the pathogen and this level of resistance can breakdown because the pathogen is highly variable due to its potential for sexual recombination. Sexual stage is reached by Didymella rabiei which is a heterothallic fungus that requires two mating types [2]. The sexual stage has been observed in chickpea field at Sidi Bel Abbes region in 1997

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