Circular cell clusters and calcium oxalate crystals: critical players in Solanaceae anther dehiscence

Circular cell clusters in Solanaceae anthers, crucial for pollen release, influence anther opening through coordinated development, programmed cell death, and calcium oxalate crystal dynamics. Circular cell clusters (CCCs), which are specialised crystal idioblasts, represent unique anatomical structures in Solanaceae anthers. These clusters may impact anther dehiscence through precisely coordinated developmental processes and programmed cell death (PCD). The dynamic metabolism of calcium oxalate (CaOx) crystals within CCCs likely contributes to PCD signalling. Although many factors, such as phytohormones, anther wall mechanics, and dehydration processes, influence anther dehiscence, it is increasingly clear that the CaOx crystals in CCCs are important for the timely degradation of CCCs and stomium cells. This review summarises the current understanding of the functions of CCCs in Solanaceae, highlighting their multifaceted roles in plant reproduction. A deeper comprehension of these mechanisms may provide insights for innovative crop improvement strategies. Similar structures in other plant families indicate a conserved evolutionary strategy for anther dehiscence across angiosperms.