Study Finds Hormone's Dual Role in Plant Flowering

A new paper presented by University of Pennsylvania researchers reveals that the plant hormone gibberellin, once believed to promote flower formation in annual plants also plays a role in inhibiting flowers from forming. Plant scientists have always believed that short-lived plants, annuals or bi-annuals, use a different strategy from long-lived plants, perennials, in regulating flower production.

The study, led by Nobutoshi Yamaguchi and Doris Wagner, looked for new genes important to the flower-forming process. The team used Arabidopsis thaliana to find direct targets of the protein LEAFY, known to promote flower formation. One gene that turned up was called ELA1, which produces a cytochrome enzyme, known to play a role in breaking down gibberellin. Their experiments showed that flowers formed much later in plants which lacked LEAFY. The researchers also found that such plants had high levels of gibberellin, while plants engineered to produce high levels of LEAFY had lower levels of the hormone and were also shorter with greater levels of chlorophyll — characteristics of gibberellin deficiency.

Results suggest that the two transition steps leading plants to produce flowers both involve gibberellin. While gibberellin promotes the first transition, when plants stop producing stems and leaves and produce an inflorescence, it inhibited the second stage, in which flowers were formed.

The results of the study are published in the journal Science (DOI: 10.1126/science.1250498). For other details, read the news release at http://www.upenn.edu/pennnews/news/plant-hormone-has-dual-role-triggering-flower-formation-penn-study-finds.