Phenylpropanoid and antioxidant changes in chickpea plants during cold stress

In creating cold tolerance, plant cells induce cascades of alterations in metabolic pathways including, phenylpropanoid pathway, the activity of antioxidant enzymes and the regulation of gene expression. In this study, some such responses were comparatively studied in two chickpea (Cicer arietinum L.) genotypes, Kabuli (Sel96Th11439) and Desi (4322) under control (23°C) and days 2 and 4 after exposing the seedlings to cold stress (4°C) in acclimated and non-acclimated plants. Under cold, the contents of hydrogen peroxide (H2O2) in Kabuli plants were lower than that of Desi plants particularly in acclimated plants. In acclimated plants, antioxidants and antioxidant enzymes such as ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) and total phenolic compounds had an important role in creating greater cold tolerance. Under these conditions, a high transcription level of phenylalanine ammonia-lyase (CaPAL), cinnamyl alcohol dehydrogenase (CaCAD) and CaLaccase genes was detected in acclimated plants which was accompanied with an increase in lignin contents. The above results indicate the crucial role of phenylpropanoid pathway in creating cold tolerance particularly in Kabuli chickpea plants, which leads to decreased levels of injuries and increased capacity in defense systems.