## 4 Discussion  
Nowadays, the increasing prevalence of extreme weather or the environment has had a negative impact on crop production [42; 43]. Drought damage is a critical element significantly influencing plant growth and yield formation. Understanding the molecular mechanism and mining stress resistance genes to carry on stress resistance breeding is an important way to deal with drought stress. Transcriptome sequencing makes it possible to obtain a large number of potential resistance genes. Here, 11,936 differentially expressed genes were generated in garlic plants exposed to simulated water stress. The findings from the present study would considerably increase the comprehension of dynamic changes in garlic under drought conditions. It is recognized that water deficit may lead to alterations at the physiological and molecular levels, thus adapting to osmotic stress induced by water deficit. This process may be accompanied by a series of changes, including purine and phenylpropanol metabolism [44], antioxidant defense system [45], flavonoid biosynthesis [46], and wax accumulation [47]. Here, we also found that phenylpropanol biosynthesis and isoflavuonoid biosynthesis were two of the most enriched KEGG pathways (Figure 4). Drought stress induced changes to the starch and sucrose metabolism, which is in accordance with the results observed in soybean [48]. Previous studies indicated that hormone biosynthesis and signaling were involved in plants exposed to water deficit. It is reported that OsMADS23 can promote ABA accumulation by activating biosynthesis genes to improve drought tolerance in rice [49]. Apple plants overexpressing _MdVQ37_ showed reduced drought tolerance with altered SA homeostasis [50]. In this study, plant hormone signal transduction took part in the process of garlic plants responding to water deficit, suggesting a potential role of plant hormones in drought tolerance. Calcium signaling initiates the MAPK cascades to activate the downstream genes to protect plant cells [51; 52]. Here, MAPK signaling pathway genes were also trapped in the response of garlic plants to water stress (Figure 4), further corroborating this view. The ABA metabolism and signaling pathway is essential for drought stress responses. Numerous studies have indicated that alterations in the transcript levels of the genes in ABA metabolism and signal transduction may make difference to plant drought tolerance. Grapevine plants overexpressing _9-cis-epoxy carotenoid dioxygenase_ exhibited improved tolerance to drought [23]. Similarly, _Arabidopsis_ plants harboring a gene encoding violaxanthin de-epoxidase from _Cerasus humilis_ showed enhanced drought tolerance [53]. Mutation in a beta-carotene hydroxylase reduced zeaxanthin and ABA levels in rice, accompanied by decreased drought resistance [54]. The overexpression of ABF3 from _Populus euphratica_, encoding an ABA responsive element binding factor, showed higher photosynthetic activity and water-use efficiency in plants subjected to drought stress [55]. In this work, genes related to ABA biosynthesis and signaling were differentially expressed, suggesting a potential role of ABA in garlic plants under drought conditions. Calcium is recognized as a second messenger to respond to external stimuli in plants. In trifoliate orange, PrtCDPK10 functioned in drought tolerance by decreasing ROS accumulation [56]. Similarly, the overexpression of wheat _TaCIPK23_ resulted in a developed root system and reduced water loss rate under drought conditions in _Arabidopsis_[57]. AKT1, KAT1, and AKT2 K\({}^{+}\) channels are important components in Ca\({}^{2+}\) mediated K\({}^{+}\) uptake in guard cells, thus exerting influence on the performance under drought stress [58]. Barleyplants with overexpressed _HuAKT2_ showed increased K\({}^{+}\) uptake, H\({}^{+}\) homoeostasis and improved tolerance to drought stress [59]. MAPK cascade genes were demonstrated to function in the drought stress response in three cotton species, and similar results were also observed in _Arabidopsis_[60; 61].