CsPPR203 regulates plastid RNA editing to mediate yellowish/albino leaf phenotypes in tea plants

Tea is an economically significant industrial crop with global production exceeding 6.5 million tons annually, providing substantial economic value across multiple industries. Yellowish-albino tea cultivars are highly valuable germplasm resources. Their distinctive metabolic profiles and elevated free amino acid content offer significant advantages for specialized tea product development. However, the molecular mechanisms underlying leaf color variation in these high value cultivars remain largely unresolved, limiting precision breeding programs. To identify candidate C-to-U editing factors in the tea plant, DYW domain sequences from three biochemically characterized editing PPR (Pentatricopeptide repeat) proteins (AtOTP86, PpPPR65, and PpPPR56) were aligned and used as seed inputs for a profile-based genome-wide scan. Combined with transcriptomic data from 148 tea samples representing diverse leaf color phenotypes, CsPPR203 was found to be significantly downregulated in yellowish-albino tea cultivars compared with conventional green-leaf cultivars. Notably, CsPPR203 expression levels in HBH (Quntizhong) green samples were 2.5-fold higher than those in yellow samples, and expression in SC1 (Shaancha 1) and LJ43 (Longjing 43) was significantly elevated relative to the albino cultivars SJB (Shuijingbai) and BY1 (Baiye 1). Sanger sequencing analysis established that CsPPR203 is responsible for C-to-U substitution at position 674 of the ndhD (NAD(P)H-quinone oxidoreductase chain 4) transcript. Yeast two-hybrid, bimolecular fluorescence complementation, and split-Luc analyses revealed that CsPPR203 directly associates with the cofactor CsMORF9.3. Loss-of-function analysis through AsODN (antisense oligonucleotide)-mediated silencing of either component markedly impaired C-to-U substitution at ndhD position 674 and triggered widespread dysregulation of chloroplast pigment biosynthesis transcripts. These findings elucidate a novel regulatory module underlying leaf color variation in tea plants, providing a theoretical framework and actionable genetic targets for molecular-assisted breeding of premium yellowish-albino cultivars.