Defense mechanism in chickpea (Cicer arientinum L.) against Ascochyta blight
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Date
2017
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Punjab Agricultural University, Ludhiana
Abstract
The present investigation was carried out on ten chickpea genotypes namely ILWC 115, C. juncea 182, ILWC 292, L 552, PBG 7, GLK 14313, HC5, GLK-08-104, GLK 12021, C. pinnatum 212 sown separately in control and sick plots infested with Ascochyta rabiei, to study the response of enzymatic antioxidants, non-enzymatic antioxidants and signalling molecules in leaves at different four stages of infestation i.e. S0 (pre-inoculatory) stage, S1 stage (7 days after infestation), S2 stage (20 days after infestation), S3 stage (30 days after infestation). The chickpea genotypes were characterized as resistant (PBG7, GLK08-104, GLK1433, ILWC292, C. juncea 182), moderately resistant (HC5), susceptible (GLK 14313, L 552, C. pinnatum 212) and highly susceptible (ILWC115) genotypes on the basis of disease severity scale. The timely upregulation and more intensity of defensive enzymes such as SOD, APX-GR followed by CAT and POD and the enzymes involved in phenylpropanoid pathway such as PAL, TAL, PPO as compared to susceptible genotypes might be responsible for resistance to ascochyta blight in resistant genotypes. The higher accumulation of H2O2, total phenols and proline in resistant genotypes and higher MDA content in susceptible genotypes also contribute to their differential tolerance behaviour towards infestation. Higher radical scavenging activities such as NO radical scavenging activity, OH free radical scavenging activity, superoxide anion radical scavenging activity and FRAP mediates the ascochyta blight tolerance in PBG7, HC5, GLK08-104,GLK12021, ILWC292, C. juncea 182 chickpea resistant genotypes as compared to GLK14313, L552, ILWC115, C. pinnatum 212 susceptible chickpea genotypes. The upregulation of defensive enzymes at later stages of infestation in GLK14313, L552, C. pinnatum 212 and their lower activities in ILWC115 might be responsible for their susceptible behaviour indicating that the time and intensity of induced defensive mechanism is an important contributing factor towards disease tolerance.
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