Submitted to: Physiological and Molecular Plant Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/1/2004
Publication Date: 10/1/2004
Citation: Cho, S., Muehlbauer, F.J. 2004. Genetic effect of differentially regulated fungal response genes on resistance to necrotrophic fungal pathogens in chickpea (cicer arietinum l.). Physiological and Molecular Plant Pathology. 64:57-66. Interpretive Summary: Ascochyta blight and Fusarium wilt are two of the most important diseases of chickpea (garbanzos) worldwide and also in the U.S. Genes in the chickpea plant regulate responses to disease causing pathogens and those responses often lead to defense against the disease. Several chemical compounds can induce these plant responses. In this research we used Salicylic acid and Jasmonic acid to induce chickpea plant responses that would be similar to the responses to the actual pathogen. Significant responses to these chemicals were found, but specific responses in plants with disease resistance genes were inconclusive. Further study is needed to determine the resistance mechanisms for fungal resistance in chickpea.
Technical Abstract: Plant resistance to pathogen infection can be achieved by systemic regulation of the defense-related genes that respond to specific systemic signals. To elucidate defense responses in chickpea (Cicer arietinum L.) against fungal pathogens, Ascochyta rabiei (Pass.) Labr. causing ascochyta blight and Fusarium oxysporum f.sp. ciceri causing fusarium wilt, expression patterns of defense related genes in chickpea after pathogen inoculation and exogenous treatments with systemic signals such as SA and Me-JA were investigated. Two blight differential germplasm lines, FLIP84-92C(2) (blight resistant and SA- and Me-JA-sensitive) and PI359075 (1) (blight susceptible and SA- and Me-JA-insensitive) showed significant differential expression patterns of the defense-related genes after A. rabiei inoculations and exogenous treatment with SA and Me-JA. However, blight resistance in the recombinant inbred lines generated from the cross of the two germplasm lines did not cosegregate with the expression of the genes induced either by pathogen inoculation or by signal chemicals. Fusarium wilt resistance in chickpea also did not require induction of the defense-related genes after Fusarium infection. These results indicated that systemic regulation of the defense-related genes at transcription level which is reportedly associated with disease resistance in other model plant species such as Arabidopsis might not confer resistance in chickpea against two necrotrophic fungal pathogens, Ascochyta rabiei (Pass.) Labr and Fusarium oxysporum f.sp. ciceri. Further studies focused on constitutive or unknown defense systems independent of SA- and JA-mediated systemic resistance mechanisms are required to understand fungal resistance mechanisms in chickpea.