Sizing up beauty: Mechanisms of petal size regulation in ornamental plants

Ornamental plants can generate higher economic value per unit area compared to traditional crops. Enhancing market share in the flower industry relies on cultivating varieties with exceptional ornamental traits. Petal size, a critical factor influencing flower shape and ornamental appeal, is a primary focus for horticultural breeding selection. In this article, we review recent advances in understanding the regulation of petal size in ornamental plants through analyzing various patterns of cell division and expansion underlying petal growth and the genes involved in the related regulatory paradigms. We further highlight the intricate network of petal size control affected by multiple phytohormones and discuss several open questions and strategies for breeding ornamental plants with desired petal size traits based on current findings.