CsLBD37, a LBD/ASL transcription factor, affects nitrate response and flowering of tea plant

• CsLBD37 , a LBD/ASL transcription factor, was cloned and functionally characterized. • CsLBD37 alters nitrate content by decreasing the expression levels of nitrogen-responsive genes. • CsLBD37 alters the morphology of main roots and lateral roots in transgenic Arabidopsis . The tea plant is widely cultivated as an economic crop throughout the world. Nitrate is an essential nutrient, as well as a key signaling molecule that controls plant growth and development. LBD transcription factors play important roles in plant nitrate response. The study of the functions of LBD transcription factors in tea plant, on the other hand, is still limited. In this work, CsLBD37 , a nitrate-induced LBD family gene from tea plant was isolated and characterized. The CsLBD37 protein was located in the nucleus and showed transcriptional activity in yeast. Under 5 mM nitrate treatment, CsLBD37 overexpression in transgenic Arabidopsis resulted in shorter main roots (0.16-, 0.45-, and 0.65-fold of wild type plants), fewer lateral roots (0.1-, 0.18-, and 0.27-fold of wild type plants), and reduced plant weight (0.36-, 0.31-, and 0.34-fold of wild type plants). In addition, the transgenic Arabidopsis contained a reduced nitrate concentration (the nitrate content of OE-1 and OE-2 in leaves was 0.45 and 0.44 times of that in non-transgenic plants, respectively) and lower expression levels of nitrate-responsive genes. In transgenic Arabidopsis, CsLBD37 overexpression results in shorter plants, earlier blooming and fewer seeds. The results proved that CsLBD37 regulates nitrate signaling in tea plants, which lays the groundwork for future studies on the nitrate response mechanism.