Biochemical and physiological response of two Lotus japonicus ecotypes under low temperature conditions.

CALZADILLA P.I.; SIGNORELLI S; MAIALE S; MONZA J; RUIZ O.A.

Congreso; 11 International Congress of Plant Molecular Biology; 2015

Lotus is an important genus of leguminosae, used as forage due to their high nutritional value and adaptability to marginal conditions for agriculture. However, its dry matter production is drastically reduced in coolest season. The acclimation response of two L. japonicus ecotypes (MG-1 and MG-20) were studied under cold stress. Plants of 3-weeks-old were analyzed at different times (first, fourth and seventh day) of stress (5-9 ± 1 °C) and control (21-25 ± 1 °C) treatment. Previous data showed that photoinhibition occurs in stress and differentially between ecotypes, being MG-1 more affected than MG-20. In this study, the Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS) production was analyzed under stress, finding no differences between treatments or ecotypes. Nevertheless, NADPH and NADP+ measurements demonstrated a reduction in NADPH in the stress treatment, and more intensively in MG-1. Antioxidant enzymes catalase (CAT), ascorbate peroxidase (APx) and superoxide dismutase (SOD) activities were measured. Only SOD isozymes showed a contrasting response between accessions and treatments, increasing more intensively in MG-20. Immunoblot of D1 and D2 proteins were done to analyze the effect of cold in photosynthesis. While D1 protein contents remained constant, D2 turnover was evident.As a conclusion, no increased in ROS and RNS were observed in the conditions studied. However, cell redox state (measured as NADPH/NADP+) seems to be affected. D2 turnover indicates an acclimation response of both ecotypes to cold stress. Our study may provide a deeper insight into the tolerance mechanism to cold stress in L. japonicus.