Maize 4-coumarate coenzyme A ligase <i>Zm4CL-like9</i> gene positively regulates drought stress response in <i>Arabidopsis thaliana</i>

Maize is a major food crop in China, and drought is one of the major abiotic stresses that threaten the growth and development of the crop, seriously affecting the crop yield. 4-coumaric acid coenzyme A ligase (<i>4CL</i>) is a key enzyme in the phenylpropane metabolic pathway, which can regulate the lignin content of the plant and play an important role in the plant's resistance to drought stress, plays an important role in plant resistance to drought stress. In the present study, we screened the differentially expressed up-regulated gene <i>Zm4CL-like9</i> under drought stress by pre-transcriptome sequencing data (PRJNA793522) in the laboratory, and analyzed the significant up-regulation of <i>Zm4CL-like9</i> gene in roots under drought stress by qRT-PCR(Real-Time Quantitative Reverse Transcription PCR). The results of prokaryotic expression experiments showed that the protein encoded by the <i>Zm4CL-like9</i> gene was able to be expressed in prokaryotic cells and could effectively improve the drought tolerance of E. coli. Phenotypic analysis of transgenic <i>Arabidopsis</i> plants under drought stress revealed that seed germination rate, root length, and plant survival after drought rehydration were significantly higher in transgenic <i>Zm4CL-like9 Arabidopsis</i> compared with wild-type <i>Arabidopsis</i>; physiological and biochemical indexes revealed that peroxidase activity, proline (Pro) content, and chlorophyll content were significantly higher in transgenic <i>Arabidopsis</i> compared with wild-type <i>Arabidopsis</i>. Under drought stress, the expression of drought-related genes was significantly up-regulated in transgenic <i>Arabidopsis</i> compared with wild-type <i>Arabidopsis</i>. Taken together, the <i>Zm4CL-like9</i> gene enhances plant resistance to drought stress by reducing reactive oxygen species accumulation in plants.