The sensory quality of black tea is intrinsically linked to cultivar genetics, yet comprehensive characterization of flavor compounds in emerging northern Guangdong black tea (NGBT) remains limited. This study employed high-performance liquid chromatography-ultraviolet (HPLC-UV) and headspace solid-phase microextraction coupled with GC-MS (HS-SPME-GC-MS) to analyze non-volatile and volatile compounds in five NGBT cultivars—Jinshahong (JSH), Danxia No.1 (DXY), Danxia No.2 (DXE), Yingde Black Tea (QTZ), and Yinghong No.9 (YHJ)—alongside sensory evaluation. Orthogonal partial least squares-discriminant analysis (OPLS-DA) identified key non-volatile discriminants (VIP > 1) ranked by contribution: total catechins > simple catechins > CG > EGCG > ester catechins > EGC. HS-SPME-GC-MS detected 97 volatiles, with eight aroma-active compounds exhibiting OAV > 1 and VIP > 1: Geraniol > Methyl salicylate > Linalool > β-Myrcene > Benzyl alcohol > (Z)-Linalool Oxide > Phenethyl alcohol > (Z)-Jasmone. These compounds drive cultivar-specific aromas in NGBTs. Findings establish a theoretical framework for evaluating cultivar-driven flavor quality and provide novel insights for targeted breeding and processing optimization of NGBTs.

In the context of increasingly frequent extreme weather events, cold injury has become a major environmental constraint limiting the growth and productivity of tea plants, particularly large-leaf tea cultivars, which are more susceptible to low-temperature stress. Pruning is a widely used agronomic practice that can effectively alleviate cold-induced damage and improve plant stress tolerance. However, the effects of different pruning intensities on overwintering cold tolerance in large-leaf tea cultivars remain poorly understood. In the present study, physiological analyses and transcriptome sequencing were performed on the ‘Yinghong 9’ cultivar under different pruning intensities. The light-pruning treatment conferred the greatest improvement in cold tolerance by enhancing antioxidant enzyme activities and the accumulation of osmotic adjustment substances. Transcriptomic analysis revealed enrichment of genes related to the MAPK signaling pathway under pruning treatment. Further weighted gene co-expression network analysis (WGCNA) combined with differential expression and KEGG enrichment analyses identified a group of candidate genes significantly associated with cold-resistance-related physiological traits, including MAPK pathway-related genes and several canonical cold-responsive genes such as RbohD and CML45; these candidates require further functional validation. These findings provide new insight into the cold-tolerance responses of large-leaf tea cultivars to different pruning intensities and highlight potential regulatory mechanisms and key associated genes involved in pruning-regulated winter hardiness.