Shedding light on the chloroplast as a remote control of nuclear gene expression

Plants rely on a sophisticated light sensing and signaling system that allows them to respond to environmental changes. Photosensory protein systems -phytochromes, cryptochromes, phototropins, and ultraviolet (UV)-B photoreceptors- have evolved to let plants monitor light conditions and regulate different levels of gene expression and developmental processes. However, even though photoreceptor proteins are best characterized and deeply studied, it is also known that chloroplasts are able to sense light conditions and communicate the variations to the nucleus that adjust its transcriptome to the changing environment. The redox state of components of the photosynthetic electron transport chain works as a sensor of photosynthetic activity and can affect nuclear gene expression by a retrograde signaling pathway. Recently, our groups showed that a retrograde signaling pathway can modulate the alternative splicing process, revealing a novel layer of gene expression control by chloroplast retrograde signaling.