A novel insight into nitrogen and auxin signaling in lateral root formation in tea plant [Camellia sinensis (L.) O. Kuntze]

Tea plant [Camellia sinensis (L.) O. Kuntze] is one of the most popular non-alcoholic natural beverage worldwide. It is a nitrogen-preferring perennial woody plant having well-developed LRs. Nitrogen fertilizer is essential for tea leaf increasing and quality. LRs are the main organs used for tea plant to absorb soil nutrients and water. Therefore, the LRs development has a direct impact on yield and quality of tea plant. Developed LRs can increase the absorption capacity of tea plant for soil nitrogen utilization efficiency. However, the molecular mechanism of nutrient conditions for LRs formation in tea plants has not yet been explored. In addition, the metabolic relationship between nitrogen and auxin has not been well studied, and the effects of nitrogen and auxin relationship on LRs formation are still not clear. The objectives of this study are to compare differentially expressed genes involved in the formation of LRs and to determine the concentration of auxin in tea plant by using RNA sequencing and RP-UPLC, respectively, under the nitrogen-deficient, nitrogen-toxicity, IBA (Indole-3-butyric acid, promoting root development), NPA (N -1-naphthylphthalamic acid, preventing root development) treatments. The mechanisms underlying LRs phenotypic changes and their responses to different nitrogen concentrations in tea plants were investigated. The signaling pathways and regulatory networks of nitrogen and auxin in LRs formation were proposed.