Hyperspectral imaging of liverwort Marchantia polymorpha identifies MpWRKY10 as a key regulator defining Foliar pigmentation patterns.

Foliar pigmentation patterns vary among plant species and growth conditions. In this study, we utilize hyperspectral imaging to assess foliar pigmentation in the bryophyte Marchantia polymorpha under nutrient stress and identify associated genetic factors. Using singular value decomposition (SVD) for feature selection, we quantitate color variations induced by deficiencies in phosphate, nitrate, magnesium, calcium, and iron. Pseudo-colored thallus images show that disrupting MpWRKY10 causes irregular pigmentation with auronidin accumulation. Transcriptomic profiling shows that MpWRKY10 regulates phenylpropanoid pathway enzymes and R2R3-MYB transcription factors during phosphate deficiency, with MpMYB14 upregulation preceding pigment accumulation. MpWRKY10 is downregulated in older, pigmented thalli under phosphate deficiency but maintained in young thalli, where it suppresses pigmentation genes. This downregulation is absent in pigmented thalli due to aging. Comparative transcriptome analysis suggests similar WRKY and MYB roles in nutrient response and pigmentation in red-leaf lettuce, alluding to conserved genetic factors controlling foliar pigmentation patterns under nutrient deficiency.