Increased leaf tocopherol and β‐carotene content is associated with the tolerance of winter wheat cultivars to frost
Janeczko, Anna | Dziurka, Michał | Pociecha, Ewa
Comparative studies in winter wheat cultivars have so far been focused on the content of tocopherols in the grains as tocopherols are an important source of vitamin E in the human diet. Our approach was to verify the following main hypothesis—whether a higher accumulation of nonenzymatic antioxidants (tocopherol, tocotrienols, β‐carotene) in the leaves of winter wheat during cold acclimation is accompanied by a higher frost tolerance of winter wheat cultivars. Seedlings of winter wheat cultivars—frost susceptible (Bystra) and frost tolerant (Nutka and Smuga)—were cold acclimated for a period of 3 weeks. To analyse the antioxidants (tocotrienols, tocopherols, β‐carotene), leaf samples were taken on the final day of the exposure to cold. Moreover, samples were also taken to estimate the content of abscisic acid, jasmonic acid and salicylic acid. After leaf chlorophyll a fluorescence measurements, the plants were exposed to frost (−8 to −14°C) and left to regrow to estimate their survival. Cultivars of winter wheat with higher accumulation of tocopherols in leaves had higher frost tolerance than cultivar with fewer tocopherols in leaves. α‐tocopherol was accumulated in cv. Bystra in the amount of 137 μg g DW⁻¹. The content of α‐tocopherol was about 26% and 90% higher in cv. Nutka and cv. Smuga, respectively. The β‐carotene content was also higher in cv. Nutka and cv. Smuga compared to cv. Bystra. This work indicates a need for further and more detailed studies on the role of tocopherols and carotenoids in the acclimation process of cereals (winter wheat) to low temperatures. The accumulation of nonenzymatic antioxidants in the cold acclimation process will be discussed against the background of the accumulation of the stress hormones and changes in the photosynthetic efficiency in the tested cultivars.
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