Effect of antioxidants on plant growth and development

The effects of natural (alpha-tocopherol and ascorbic acid) and synthetic ( 3,5-dibutyl-4-hydroxytoluene, BHT) antioxidants added to growth medium on t he callus formation, plant regeneration in a tissue culture of tomato plant s, and growth of intact wheat seedlings was studied. The number and length of roots in regenerants from tomato cotyledons increased in the presence of alpha-tocopherol (2.7-27 mg/l). Ascorbic acid (10 mg/l) induced an increas e in the mass of calluses originated from hypocotyl but inhibited root form ation in regenerants from tomato cotyledons at 25 degrees C. In contrast, i t strongly stimulated root growth and formation at 15 degrees C, BHT at 1.3 mg/l significantly enhanced the development of regenerants, but at 60 mg/l it strongly suppressed their development. BHT at 50 mg/l strongly inhibite d the growth of etiolated wheat seedlings but slowed senescence of coleopti les and induced synthesis of pigments (most probably, carotenoids) that acc umulated mainly in roots, Thus, antioxidants, including BHT, effectively re gulate in vitro and in vivo plant growth and development. Similar to other known regulators of plant growth, antioxidants may exert different and even opposite effects depending on their concentration in a medium and (for nat ural antioxidants) their explant origin and cultivation conditions (tempera ture).