## 1 Introduction  
Tea is a globally popular beverage known for its distinctive flavor and health-promoting properties [1; 2; 3]. Tea products are primarily derived from the buds and young or mature leaves of the tea plant (_Camellia sinensis_) [4]. Consequently, the bioactive compounds responsible for tea's flavor and health qualities are predominantly found in these buds and leaves. Several factors, including tea plant cultivar [5; 6; 7], environmental growing conditions [8; 9; 10; 11; 12], and post-harvest processing methods [13; 14; 15; 16], significantly influence the production and accumulation of these active metabolites, thereby affecting the overall quality of the tea. The quality of fresh tea leaves is a fundamental factor in determining the final quality of the processed tea product. It is generally accepted that only high-quality fresh leaves can produce premium tea. The accumulation of bioactive compounds in fresh tea leaves is closely related to both the tea plant cultivar and its growing environment. Among environmental factors, drought is a common stressor that significantly affects tea plant growth and the accumulation of metabolites in young shoots [17; 18; 19]. Some studies have shown that moderate drought can enhance tea flavor by balancing specific metabolite levels in fresh leaves [19], while slight drought stress has been found to promote polyphenol synthesis, leading to improved tea flavor quality [20]. In addition, drought stress is also known to influence the formation of tea's unique aromatic compounds. For example, the characteristic aromas of Keemun black tea from China, high-aroma Ceylon tea from Sri Lanka, and Darjeeling tea from India have been associated with short-term drought conditions [21]. In China's Yunnan province, local tea plantation smallholders also observe that spring drought positively influences the aroma of tea [22]. In a previous study on _Lington Dancong_ tea plants under drought stress, it was found that different levels of drought can induce the synthesis of varying types of aromatic compounds, with the number of aroma compounds in fresh tea leaves increasing as drought stress intensifies [23]. Additionally, research indicates that slight drought stress can lead to the enrichment of metabolic pathways involved in linoleic acid and butyrate acid metabolism, further suggesting drought's role in modulating tea aroma [20]. Despite the existing research on the positive effects of moderate or slight drought on tea flavor and aroma, the mechanisms by which drought stress specifically influences the formation of key aroma compounds in tea remain insufficiently explored. Volatile compounds (VOCs) in tea, although comprising only 0.01% of the dry weight, are crucial for its aroma [24]. To date, over 700 VOCs have been identified in tea, predominantly alcohols, aldehydes, ketones, and terpenes [4]. However, only a limited number of these compounds, with odor activity values (OAVs) exceeding 1, are considered to make significant contributions to the overall aroma, thus being classified as key odor-active aroma compounds [25; 26]. Most previous research has focused on identifying key odor-active aroma compounds in processed tea [13; 27; 28; 29], with limited attention given to fresh tea leaves prior to processing, particularly concerning the effects of abiotic stresses like drought on the formation of key odor-active aroma compounds in fresh tea leaves. This study aims to address this gap by evaluating the effects of field drought stress on the key odor-active aroma compounds in fresh leaves from two widely cultivated tea cultivars in China, Fuding Dabai (FD) and Wunizuzo (WNZ). The primary objective is to assess the impact of drought on the volatile profile and aroma characteristics of fresh tea leaves and to elucidate the differential metabolic pathways involved in aroma formation under drought conditions between the two cultivars. Gas chromatography-mass spectrometry (GC-MS) is a widely used technique for the identification and quantification of VOCs in tea [4; 14; 30].