Tea plant (Camellia sinensis) is an important horticultural crop. The quality and productivity of tea plants is always threatened by various adverse environmental factors. Numerous studies have shown that intercropping tea plants with other plants can greatly improve the quality of their products. The intercropping system of Chinese chestnut (Castanea mollissima) and tea plants is an agricultural planting model in which the two species are grown on the same piece of land following a specific spacing and cultivation method. Based on a comparative transcriptome analysis between Chinese chestnut tea intercropped plantations and a pure tea plantation, it was found that the expression levels of the WRKY genes were significantly upregulated under the intercropping pattern. In this study, we cloned a candidate gene, CsWRKY48, and verified its functions in tobacco (Nicotiana tabacum) via heterologous transformation. The contents of protective enzyme activities and osmoregulatory substances were significantly increased, and the trichomes length and density were improved in the transgenic tobacco lines. This phenotype offered an enhanced resistance to both low temperatures and aphids for transgenic lines overexpressing CsWRKY48. Further analysis indicated that the CsWRKY48 transcription factor might interact with other regulators, such as CBF, ERF, MYC, and MYB, to enhance the resistance of tea plants to biotic and abiotic stresses. These findings not only confirm the elevated resistance of tea plants under intercropping, but also indicate a potential regulatory network mediated by the WRKY transcription factor.
Keywords: CsWRKY48; cold resistance; insect resistance; tea plants intercropped with Chinese chestnut; trichomes.