A Study on the Response Mechanism of <i>Davidia involucrata</i> Baill. to Drought Stress Based on Transcriptomic Analysis

<i>Davidia involucrata</i> Baill. is a species that thrives in warm, humid climates with consistently moist soil conditions. With rising global temperatures and an increasing frequency of droughts, the natural habitat of <i>Davidia involucrata</i> Baill. is facing severe threats. In-depth investigation of the molecular mechanisms underlying <i>Davidia involucrata</i> Baill.'s response to drought stress is crucial for the conservation of this rare species and the enhancement of its environmental adaptability. This study systematically analyzed the drought stress response of <i>Davidia involucrata</i> Baill. under varying light conditions through transcriptome data analysis. The results showed that under different light conditions, <i>Davidia involucrata</i> Baill. responded to drought stress by regulating its internal osmotic balance via the "response to mannitol" pathway. Notably, the molecular mechanisms by which <i>Davidia involucrata</i> Baill. responds to drought stress vary significantly under different light conditions. Compared with high light intensity, <i>Davidia involucrata</i> Baill. under shaded conditions responded to drought stress by upregulating glycosyltransferase-related pathways. In addition, three soil drought-related pathway genes (SDRPGs) (<i>Dinv08247</i>, <i>Dinv34952</i>, and <i>Dinv00865</i>) involved in the regulation of drought stress in <i>Davidia involucrata</i> Baill. were identified, and both ABA and SA were found to influence their expression. As a key environmental factor, air humidification may enhance the drought stress adaptability of <i>Davidia involucrata</i> Baill. by modulating ABA biosynthesis. The SDRPGs and signaling pathways identified in this study may serve as important candidate targets, providing theoretical guidance and scientific reference for the genetic improvement of drought resistance in <i>Davidia involucrata</i> Baill. and the long-term conservation of rare plant resources.