Effects of Blue and Green Light on Pigment Content, Photosynthesis, and Chloroplast Structure in CRY1a-Deficient Tomato Mutants

Cryptochrome 1a (CRY1a) mediates blue-light signalling in tomato, but its contribution to acclimation to combined blue and green light remains unresolved. We compared wild-type (WT) and cry1 plants under white fluorescent light (WFL), blue light (BL), green light (GL), and BL/GL using gas exchange, A/Ci curves, chlorophyll fluorescence, pigment composition, electron microscopy, transcript abundance, and phenolic metabolism. Under BL, cry1 had a lower photosynthesis rate, stomatal conductance, and Y(II), despite higher chlorophyll content and grana area. Under BL/GL, the photosynthesis rate and stomatal conductance were approximately 35% lower in cry1, and Vcmax, Jmax, and TPU decreased by 48–57%. Y(II) was lower, and Y(NO) was higher in cry1 than in WT. Under BL/GL, the grana area was lower in cry1, whereas the starch-grain area, stroma area, and plastoglobule number showed small differences that were not statistically significant. Transcript responses varied among spectra and functional groups. These results support a contribution of CRY1a to the coordination of structural and physiological acclimation to light quality. The BL/GL response is consistent with an imbalance between CO2 supply and carbon utilization that may promote photoprotective feedback.