Overexpression of SUMO E3 ligase HPY2 regulates the cell cycle in petunia development

Abstract

Sumoylation is a post-translational modification that mediates several regulatory processes in plants. It is associated with developmental processes such as cellular division, expansion and differentiation, and vegetative and reproductive growth. The primary function of SUMO E3 ligases is to control the mitotic cycle and maintain meristematic cells. Arabidopsis thaliana HIGH PLOIDY2 (HPY2), a SUMO E3 ligase, might therefore be expected to promote cell division and increase organ size when overexpressed in the model ornamental plant Petunia multiflora. One month after Agrobacterium-mediated transformation, nine putative transgenic P. multiflora plants were regenerated on selection medium, and were found to have high expression levels of AtHPY2. The proportion of cells in G2M phase, length of in vitro-cultivated plantlets, and trichome length all increased in transgenic lines compared with the wild type (WT). Transgenic petunia lines also exhibited increased growth, leaf and flower area, and flower number. Flowering time was also faster in transgenic P. multiflora than in the WT, and flower numbers increased. These results suggest that AtHPY2 overexpression stimulates cell division. This finding may be useful in controlling plant and flower size, and flowering timing and abundance in P. multiflora and other ornamentals.