Transcriptome analysis of tea (Camellia sinensis) leaves in response to ammonium starvation and recovery

The tea plant is a kind of ammonium-preferring crop, but the mechanism whereby ammonium (NH(4)(+)) regulate its growth is not well understood. The current study focused on the effects of NH(4)(+) on tea plants. Transcriptomic analysis was performed to investigate the early- and late-stage NH(4)(+) deprivation and resupply in tea plants shoots. Through short- and long-term NH(4)(+) deficiency, the dynamic response to NH(4)(+) stress was investigated. The most significant effects of NH(4)(+) deficiency were found to be on photosynthesis and gene ontology (GO) enrichment varied with the length of NH(4)(+) deprivation. Enriched KEGG pathways were also different when NH(4)(+) was resupplied at different concentrations which may indicate reasons for tolerance of high NH(4)(+) concentration. Using weighted gene co-expression network analysis (WGCNA), modules related to significant tea components, tea polyphenols and free amino acids, were identified. Hence, NH(4)(+) could be regarded as a signaling molecule with the response of catechins shown to be higher than that of amino acids. The current work represents a comprehensive transcriptomic analysis of plant responses to NH(4)(+) and reveals many potential genes regulated by NH(4)(+) in tea plants. Such findings may lead to improvements in nitrogen efficiency of tea plants.