CsNYC1a Mediates Chlorophyll Degradation and Albino Trait Formation in the Arbor-Type Tea Plant Camellia nanchuanica .

Albino germplasms are prized tea plant mutants with yellow/white leaves. However, understanding of the albino mechanisms in non- Camellia sinensis tea species remains limited. This study elucidated the albino trait formation in Nanchuan Dachashu ( C. nanchuanica ), an arbor-type tea species, and its association with tea quality. The yellow-leaved albino individual NH1 exhibited abnormal chloroplast ultrastructure and reduced chlorophyll/carotenoid levels compared to green-leaved NL1. Integrating transcriptomics, metabolomics, yeast one-hybrid, and transgenic approaches identified the chlorophyll b reductase gene CsNYC1a as a key regulator, which was significantly up-regulated in NH1, and its overexpression in Arabidopsis recapitulated the albino phenotype. In yeast, histone CsH1.2 binds to the CsNYC1a promoter. These findings suggest that CsH1.2- CsNYC1a -mediated chlorophyll degradation may be a key mechanism underlying albino formation in Nanchuan Dachashu. In addition, as a germplasm with higher polyphenol-to-amino acid ratio than NL1, NH1 offers more possibilities for breeding and application.