Mechanism of floret abortion induced by light signal blocking in juvenile spikes of wheat

In our previous research, we firstly demonstrated blocking the light to the juvenile spike directly and qualitatively affected floret fertility by affecting anther greening and inducing pollen sterility in wheat. However, the underlying mechanisms remain unclear. Here, we integrated morphology, cytology, physiology and transcriptome to investigate the differences in spike fertility under control (CT) and light blocking (LB) treatments from jointing to either anthesis (LB_J-A) or booting (LB_J-B). Our results revealed that LB affected anther greening by disturbing chloroplast development and chlorophyll synthesis, suggesting that light received by the juvenile spike is essential for anther greening. The downregulation of genes involved in photosynthesis and chlorophyll biosynthesis suppressed the expression of enzymes in fatty acid, lignin, and starch metabolism, and combined with tapetum degradation resulted in abnormal pollen exine formation and pollen sterility. Collectively, this study elucidates the possible mechanism by which light blocking inhibits anther greening and leads to pollen sterility. These findings provide novel insights into light blocking regulating spike fertility, advancing the understanding of the regulation mechanism of reproductive development in wheat.