CsGAT1 modulates GABA metabolism and positively regulates cold resistance in tea plants

Tea plants (Camellia sinensis) are perennial woody economic crops that are often exposed to a range of abiotic stresses, especially low temperatures, during development. γ-Aminobutyric acid (GABA) is a nonprotein amino acid widely distributed in plants that is involved in the low-temperature response of plants. Here, we found that CsGAT1 was upregulated in tea leaves subjected to low-temperature stress according to transcriptomic data. Heterologous expression of CsGAT1 in a yeast mutant revealed that it specifically transports GABA. Subcellular localization assays revealed that CsGAT1 was located on the plasma membrane. The organizational localization experiments revealed that the expression level of CsGAT1 was relatively high in the old leaves and roots and relatively low in the flowers. Testing of different cold-tolerant tea germplasm resources revealed that cultivars with relatively low cold resistance presented relatively low CsGAT1 expression and GABA levels. In addition, Arabidopsis plants overexpressing CsGAT1 presented high levels of GABA accumulation and significant low-temperature resistance. In summary, we believe that CsGAT1 regulates the ability of tea plants to resist low-temperature stress by changing the concentration of GABA inside and outside the cell. This study provides a theoretical basis for breeding new tea cultivars with strong resistance to low-temperature stress during production.