The phytochrome-interacting factors (PIFs) proteins belong to the subfamily of basic helix–loop–helix (bHLH) transcription factors and play important roles in chloroplast development and chlorophyll biosynthesis. Currently, knowledge about the PIF gene family in Camellia sinensis remains very limited. In this study, seven PIF members were identified in the C. sinensis genome and named based on homology with AtPIF genes in Arabidopsis thaliana. All C. sinensis PIF (CsPIF) proteins have both the conserved active PHYB binding (APB) and bHLH domains. Phylogenetic analysis revealed that CsPIFs were clustered into four groups—PIF1, PIF3, PIF7, and PIF8—and most CsPIFs were clustered in pairs with their corresponding orthologs in Populus tremula. CsPIF members in the same group tended to display uniform or similar exon–intron distribution patterns and motif compositions. CsPIF genes were differentially expressed in C. sinensis with various leaf colors and strongly correlated with the expression of genes involved in the chlorophyll metabolism pathway. Promoter analysis of structural genes related to chlorophyll metabolism found DNA-binding sites of PIFs were abundant in the promoter regions. Protein–protein interaction networks of CsPIFs demonstrated a close association with phytochrome, PIF4, HY5, TOC1, COP1, and PTAC12 proteins. Additionally, subcellular localization and transcriptional activity analysis suggested that CsPIF3b was nuclear localized protein and possessed transcriptional activity. We also found that CsPIF3b could activate the transcription of CsHEMA and CsPOR in Nicotiana benthamiana leaves. This work provides comprehensive research of CsPIFs and would be helpful to further promote the regulation mechanism of PIF on chlorophyll metabolism in C. sinensis.

Tea leaf development is a biological process marked by sequential morphogenesis that directly affects tea yield and quality. Despite their importance, the dynamic regulatory mechanisms governing these developmental stages remain poorly understood. In this study, we utilized tea buds, first leaves, second leaves, and third leaves from tea plants as experimental materials. By integrating transcriptomic sequencing with biochemical analysis, we systematically elucidated the transcriptional-metabolic co-regulatory network underlying leaf morphogenesis. The findings revealed significant differences in the leaf transcriptomes across developmental stages, with the most pronounced differentiation observed between buds and mature leaves. The comparison of bud vs. 3 ^rd leaf identified the highest number (6, 854) of differentially expressed genes, which were primarily concentrated in the KEGG metabolic pathways. Core metabolites, such as catechins, free amino acids, and alkaloids, were predominantly enriched in buds and young leaves, with most exhibiting a significant decline as the leaves matured. However, O -methylated catechins were significantly enriched in mature leaves. The expression of these core metabolites is regulated by differentially expressed genes in the phenylpropanoid and flavonoid pathways ( CHS , ANS , SCPL , OMTs , etc.), theanine biosynthesis genes ( ALaDC , ALaAT , TS , etc.), and purine alkaloid biosynthesis genes ( IMPDH , SAMS , TCS , etc.). Correlation analysis indicated that most free amino acids (L-The, Glu, Gln, Asp, Ala, and GABA) exhibited significant positive correlations with alkaloids and catechins (C, GC, CG, EC, and ECG), whereas correlations with O -methylated catechin components were weak. Real-time quantitative PCR analysis revealed that 108 genes were significantly differentially expressed, with functions primarily involving cell wall synthesis and remodeling ( CER3 , PRP4 , EXPA1 , etc.), photosynthesis ( ndhL ), plant hormone signaling regulation ( SAUR23 , CYP85A1 , IAA14 , etc.), cell cycle ( CYCD1-1 , CYCA2-4 ), signal transduction ( MKK6 , MLO6 ), defense and secondary metabolism ( STR1 ), and transcription factors (GRF1, MYB17, bHLH94, etc.). Furthermore, the promoter regions of functional genes related to leaf development showed significant enrichment of MYB and MYC transcription factors, as well as cis-regulatory elements for hormones (ABRE, ERE, TCA-element), light (GT1-motif, GATA-motif, TCT-motif), and stress signals (ARE, STRE, W box). This study identified the core genes and metabolic mechanisms underlying leaf morphogenesis in tea plants, providing a theoretical basis for high-quality cultivation of tea.

The Stress-Repressive Zinc Finger (SRZ) family is a class of zinc finger proteins in plants that has been closely associated with plant growth, development, and stress responses. In this study, we conducted a genome-wide identification of the SRZ family members and identified 14 and 10 members in rice and Arabidopsis, respectively. We further characterized their phylogenetic relationships, gene structures, conserved motifs, promoter cis-elements, synteny, and spatiotemporal expression patterns. To investigate the functional role of this family in rice, we generated targeted mutants of OsSRZ1 using the CRISPR/Cas9 system. Phenotypic analysis revealed that srz1 knockout mutants exhibited significantly reduced plant height. Notably, the homozygous mutant srz1 completely failed in panicle exsertion from the flag leaf sheath, resulting in complete enclosure, whereas the heterozygous mutant srz1(h) exhibited only partial panicle exsertion. Further cytological observations revealed abnormal floral organ development and premature anther senescence in srz1, accompanied by a significant reduction in seed setting rate—srz1(h) set significantly fewer seeds, whereas srz1 exhibited complete sterility with a seed setting rate of 0%. Collectively, these findings suggest that members of the SRZ family may play important roles in rice growth and development. Our results demonstrate that OsSRZ1 is a critical regulator of plant height and panicle exsertion by regulating internode elongation, and that its disruption leads to premature anther programmed cell death (PCD) and consequent seed setting failure.