The response of Anabaena sp. to gibberellic acid

In this study, the effect of gibberellic acid on vegetative and heterocyst cell size, inducing sugar and protein content was investigated in Anabaena at three durations (7, 14 and 21 days). According to the results, vegetative cell size did not show any significant differentiation under gibberellic acid treatments and time duration. Length and width of heterocyst cells showed a significantly different impact only with 10µM gibberellic acid at 7-day-old cultures. Algae treated with gibberellic acid had more fresh weight. Gibberellic acid induced heterocyst formation after 14 and 21 days. The amount of photosynthetic pigments increased in the 7 and 14-day cultures and decreased in the 21-day cultures. Application of gibberellic acid to the culture medium did not affect heterocyst percentage after 7 days, but it increased the heterocyst numbers in the 14 and 21-day cultures. Reducing sugar content changed dependence of gibberellic acid concentration and growth period. Treatment with gibberellic acid could increase protein content at different concentration and growth period. The results of this research showed notable effect of this plant growth regulator on Anabaena.