The metabolomics and transcriptomics of Atraphaxis bracteata reveal age‐related molecular alterations under naturally high temperature and drought conditions

Abstract High temperature and drought are common environmental stresses that desert plants must withstand to grow and reproduce. In order to understand the resistance mechanisms of the desert plant Atraphaxis bracteata (A. Los) responding to natural high temperature and drought conditions, we combined physiological characteristics, transcriptome, and metabolome analysis to explore its responses in three different plant ages and CK. The results showed that most physiological indicators of A. bracteata increased with the age, except for SOD activity. There were 4 698, 7 594, and 8 485 differentially expressed genes (DEGs) and 119, 124, 188 differential expressed metabolites (DAMs) in the 3‐age‐old (T1), 5‐age‐old (T2) and 15‐age‐old (T3) plants compared to the CK, respectively. These DEGs were mainly enriched in plant hormone signal transduction, phenylpropanoid biosynthesis, AMPK signalling pathway, flavonoid biosynthesis, circadian rhythm‐plant pathways, glycine, serine, and threonine metabolism pathways. At the same time, the enriched DAMs were mainly involved in the aminoacyl‐tRNA biosynthesis pathway, arginine and proline metabolism pathway, flavonoid biosynthesis, and others. In addition, most DEGs involved in flavonoid biosynthesis, photosynthesis and plant hormones closely associated with abiotic stress were down‐regulated, and which numbers increased with age. Moreover, a higher number of DEGs and DAMs accumulated with age, which may be the key factor for the age‐dependent resistance of A. bracteata to abiotic stress. Therefore, these results could provide a way to better understand the stress resistance mechanism and provide a reference for further exploitation and utilization of A. bracteata .