Antioxidant Protection System and Photosynthetic Pigment Composition in Secale cereale Subjected to Short-Term Temperature Stresses

Plants are often exposed to short-term temperature stresses (average 2-4 hours) or “temperature drops”. It is in the first hours of stress (alarm phase of response) that metabolic changes occur, which go on to contribute to the formation of the primary stress-induced response.

Winter rye Secale cereale L. ‘Boguslavka’ plants were grown under controlled conditions in a vegetation chamber. Fourteen-day-old plants exposed to short-term heat (+40°C, 2 h) and cold (+4°C, 2 h) were studied. The dynamics and distribution of free amino acids (AAs), total phenols (TPHs), and flavonoids (TFs), as well as the content of photosynthetic pigments, were all determined according to the standard procedures.

Accumulation and distribution of secondary metabolites in the organs of winter rye plants depended on the type of temperature, stress, and the plant organ. In the first phase of alarm in cold-resistant winter rye ‘Boguslavka’ after cold stress increased the accumulation of free AAs (GABA, Pro, Asp, Cys, and Val) and decreased the content of flavonoids and chlorophyll. Both types of stress inhibited the accumulation of TPHs, and this effect was more pronounced under heat stress.

Quantitative and qualitative changes in the accumulation and distribution of low molecular weight protectors indicated that AAs and TPHs are involved in response to both types of short-term temperature stresses in winter rye ‘Boguslavka’ plants. The ability to accumulate free amino acids (GABA, Pro, Asp, Cys, and Val) in the roots after cold stress is considered one of the prerequisites for cold resistance. The photosynthetic apparatus is susceptible to temperature stressors in the alarm phase of response, as indicated by the significantly decreased photosynthetic pigment.