Shade-Avoidance Transcriptome Shifts and Carotenoid Depletion in Cichorium intybus Induced by Customized Dye-Sensitized Solar Cell Light Filtering

The transition toward energy-sustainable greenhouses currently demands photovoltaic covers that can guarantee crop yield and quality by minimizing their interference with photosynthetically active radiation. Here, the impact of a novel semi-transparent dye-sensitized solar cell (DSSC) module, based on the BTD-DTP1 dye, was evaluated, considering the growth and molecular profile of radicchio plants (Cichorium intybus var. latifolium cv. Precoce). They were cultivated for 60 days under a customized-DSSC panel, clear glass, or without cover. Whole-transcriptome profiles were obtained through RNA sequencing (RNA-seq), and carotenoid and phenylpropanoid contents were analyzed. The customized-DSSC filtered light induced elongated stems and narrower leaves than the other conditions. RNA-seq data showed the upregulation of pathways associated with shade avoidance responses, including gibberellin and brassinosteroid signalling, cell-wall remodelling and nitrate transport, while photosynthesis-related ones and carotenoid biosynthesis were repressed. Consistently, neoxanthin, violaxanthin, lutein and β-carotene levels decreased in plants grown under customized-DSSC. These changes resulted from the reduced light intensity and altered light spectrum transmitted by the panel, depleted in blue and enriched in far-red wavelengths. Overall, the DSSC panel triggered the reallocation of plant resources from the photosystems toward rapid elongation, with potential consequences for crop yield. The identified molecular markers may be useful for optimizing DSSC devices and hybrid lighting strategies aimed at limiting shade-avoidance while maintaining crop productivity in agrivoltaic systems.