Genomic insights in moss gibberellin biosynthesis

Abstract

Gibberellins are phytohormones that are essential for proper growth and development of flowering plants. In bryophytes, however, the presence of gibberellins has not been firmly established, because previous reports of gibberellin-like activities were not accompanied by definitive chemical identification. By comparison, the other classical phytohormones auxin, cytokinin, abscisic acid and ethylene have been unambiguously detected in both mosses and liverworts, and their functions have been demonstrated to be very similar to those in flowering plants. The study of gibberellins in bryophytes lagged behind those of other phytohormones presumably because of the bewildering complexity and diversity in their chemical structures. In addition, working with bryophytes becomes even more challenging given their small size and the lack of obvious developmental mutants in the gibberellin signaling pathway. On the other hand, the recent sequencing of the Physcomitrella patens genome provides exciting opportunities to tackle this problem. Genes that may be involved in gibberellin biosynthesis have now been identified, paving the way for molecular genetic experiments that could reveal the role of gibberellins in bryophyte development. As bryophytes represent the earliest diverging lineages of land plants, such studies can also provide insights into how the gibberellin pathway may have evolved in the course of land plant evolution.