Transcriptomics analysis reveals Xanthoceras sorbifolia Bunge leaves' adaptation strategy to low nitrogen

Key messageThis study enriched the understanding of the mechanism of nitrogen tolerance and starvation of yellowhorn and provided a reference for the breeding of low-nitrogen tolerance germplasm in the future.Yellowhorn is a rare woody oil crop in China, which can survive in barren, drought, cold, and even saline-alkali environments. However, its growth and development can be seriously affected by low-nitrogen stress. A comprehensive understanding of its transcriptional regulation activities under low-nitrogen stress is expected to indicate the key molecular mechanisms of its tolerance to low nitrogen levels. In this study, yellowhorn was divided into control, low-nitrogen, and nitrogen-free groups for treatment. Samples were treated for 15 days before assessing physiological characteristics and transcriptome analysis. Under low-nitrogen and no-nitrogen condition, a total of 10,733 differentially expressed genes were identified, among which 3870 genes were up-regulated and 6,863 genes were down-regulated. Under low-nitrogen stress, the most up-regulated genes were enriched in the phenylpropane synthesis pathway, flavonoid synthesis pathway, and plant hormone signal transduction pathway. Our determination of total flavonoids and proanthocyanidins also verified the upregulation of these three pathways. Brassinosteroid, salicylic, and jasmonic acid (BR, SA and JA, respectively) pathway-related genes were significantly up-regulated in the signal transduction pathway of plant hormones. This study provided a comprehensive review of the transcriptomics changes of yellowhorn under low nitrogen stress and detailed its insights into the relevant mechanism of BR, SA, and JA signaling pathway in resisting low-nitrogen stress, laying a solid foundation to further identify the corresponding molecular mechanism of yellowhorn and other woody oil plants.