CsABF8 mediates drought-induced ABA signaling in the regulation of raffinose biosynthesis in Camellia sinensis leaves.

Drought has become an important environmental stress limiting the growth and development of Camellia sinensis due to its moisture-loving and temperature-tolerant nature. ABA-response element binding factor (ABFs) is a key transcriptional regulator in the ABA signaling pathway that regulates plant responses to hormones and adversity. However, their roles and regulatory mechanisms in tea tree remain unknown. To investigate the drought response in Camellia sinensis, drought-sensitive (Fuyun No.6, FY) and drought-tolerant (Taicha No.12, TC) tea cultivars were treated with exogenous PEG and ABA and subjected to non-targeted metabolomics by Ultra Performance Liquid Chromatography-Electrospray Ionization-Triple Quadrupole tandem Mass Spectrometry (UPLC/ESI-Q TRAP-MS/MS). The bioactive carbohydrates galactinol and raffinose were identified as potential drought regulators. Analysis of transcriptomics data identified potential drought tolerant target genes, namely CsGolS1/2, encoding galactinol synthases, CsRaf6, a raffinose synthase, and CsABF8, a transcriptional regulator in the ABA-response element binding factor family. The tea CsSnRK2.8-CsABF8-CsGolS1/CsGolS2/CsRaf6 regulatory module induced in response to drought stress was constructed using multiple molecular validation tools. This preliminary analysis of the molecular mechanism by which CsABF8, a regulator on the ABA signaling pathway, mediates the differences in drought tolerance in different tea cultivars provides a theoretical basis for the selection and breeding of drought-resistant varieties.