The fruitENCODE project sheds light on the genetic and epigenetic basis of convergent evolution of climacteric fruit ripening

Fleshy fruit evolved independently multiple times during angiosperm history. Many climacteric fruits utilize the hormone ethylene to regulate ripening. The fruitENCODE project shows there are multiple evolutionary origins of the regulatory circuits that govern climacteric fruit ripening. Eudicot climacteric fruits with recent whole-genome duplications (WGDs) evolved their ripening regulatory systems using the duplicated floral identity genes, while others without WGD utilised carpel senescence genes. The monocot banana uses both leaf senescence and duplicated floral-identity genes, forming two interconnected regulatory circuits. H3K27me3 plays a conserved role in restricting the expression of key ripening regulators and their direct orthologs in both the ancestral dry fruit and non-climacteric fleshy fruit species. Our findings suggest that evolution of climacteric ripening was constrained by limited availability of signalling molecules and genetic and epigenetic materials, and WGD provided new resources for plants to circumvent this limit. Understanding these different ripening mechanisms makes it possible to design tailor-made ripening traits to improve quality, yield and minimize postharvest losses. One Sentence Summary The fruitENCODE project discovered three evolutionary origins of the regulatory circuits that govern climacteric fruit ripening.