Functional study of the <italic>BnGCL1 </italic>gene in ramie (<italic>Boehmeria nivea </italic>L.) in response to drought stress

Drought is one of the major environmental stresses that affects plant growth and development. In this study, the functional role of the BnGCL1 gene in the drought stress response of ramie (Boehmeria nivea L.) was investigated. The results showed that the gene contains a maximum open reading frame (ORF) of 1581 bp, encoding a protein of 526 amino acids. The predicted protein has an isoelectric point of 5.79, a molecular weight of 59,123.98 Da, a fat index of 78.78, and an instability index of 37.42, indicating that it is a stable protein. BnGCL1 is expressed in the roots, stems, and leaves of ramie, and its expression is induced by drought stress. Under drought conditions, transgenic plants overexpressing BnGCL1 exhibited significantly greater root length, fresh weight, chlorophyll a, and chlorophyll b contents compared to wild-type plants. In addition, the activities of antioxidant enzymes such as APX and γ-GCL, as well as the levels of osmotic regulators including GSSG and Pro, were significantly altered. Overexpression of BnGCL1 also markedly upregulated the expression of drought-responsive genes, including AtGST1, AtGST11, AtNCED3, and AtWRKY40, suggesting that BnGCL1 enhances drought tolerance by modulating the antioxidant defense system and drought-responsive signaling pathways. Gene silencing experiments using VIGS technology further confirmed that suppression of BnGCL1 reduces drought tolerance in ramie, highlighting its critical role in drought response. This study reveals the important function of BnGCL1 under drought stress and provides a theoretical foundation for elucidating the molecular mechanisms of drought tolerance and for breeding drought-resistant ramie varieties.