Brassinosteroid improves content of antioxidants in seeds of selected leguminous plants

The content of antioxidants (tocopherols, trocotrienols, ascorbic acid, beta-carotene) as well as soluble proteins, total fats and soluble sugars were studied in the seeds of pea and lupine after application of brassinosteroid (24-epibrassinolide). Plants were cultured in separate pots in an open vegetation hall in 2010. The following year, a field experiment was carried out in a randomized block design where plants were growing in rows, directly in the soil. 24-Epibrassinolide (0.25-0.5 mg dm-3) was applied via spraying or watering of the flowering plants. Experiments were done during natural vegetation seasons (spring-summer, latitude: 50 degrees03' N, longitude: 19 degrees 55' E) and seeds were collected after maturation. In the pea pot experiment, gamma-tocopherol content was increased (9%-15%) in seeds after brassinosteroid spraying (0.5 mg dm-3). In the lupine field experiment, alpha- and gamma-tocopherol content was elevated in seeds (8%-84%) after brassinosteroid application (0.25 mg dm-3) via both methods. In the pea field and pot experiment, the ascorbic acid content was increased (18-52%) after watering plants with 24-epibrassinolide (0.25 mg dm-3). In lupine seeds, ascorbic acid as well as beta-carotene content was elevated after brassinosteroid watering (0.25 mg dm-3). The brassinosteroid effect on the content of proteins, sugars, and fats in seeds was also studied. The results obtained in our study show the possibility of using brassinosteroid to manipulate plant seed content, which may be important from a nutritional point of view. Moreover, the studies reveal some mechanisms of brassinosteroid action on the metabolism of seeds.