Involvement of type-f thioredoxins during germination and early seedling development and in response to oxidative stress in Arabidopsis thaliana

Abstract

Thioredoxins (TRXs) are important components of redox-regulated systems involved in maintaining and regulating the cellular redox environment during growth and development and in response to abiotic and biotic stresses. Plants possess several types of TRX localized in various compartments, including five different types of chloroplastic TRXs. Arabidopsis thaliana contains two chloroplastic type-f TRXs, TRX f1 and TRX f2, involved in the regulation of light-dependent activation of photosynthesis and carbon metabolism. However, little is known about their role during development and in response to stress. We used single and double mutants of TRX f1 and TRX f2 to assess their roles during seed germination and seedling development. Loss of both TRX f1 and TRX f2 induced faster germination and seedling development associated with reduced sensitivity to abscisic acid. This suggests that type-f TRXs negatively regulate seed germination and seedling development. Moreover, double-mutant seedlings were more sensitive to methyl viologen and UV-C irradiation than the wild-type seedlings, indicating that loss of type-f TRXs increases sensitivity to oxidative stress. Overall, these results indicate that type-f TRXs contribute to maintaining an adequate cellular environment required for a tight regulation of germination and a better tolerance to oxidative stress.