Abstract:Flavonoids play an important role in plant resistance to low temperature stress. To reveal the effects of low temperature on flavonoid synthesis in leaves of Phyllostachys edulis, the content of flavonoid in leaves of bamboo seedlings at different growth stages and under low temperature stress was determined by spectrophoto- metric method, the key enzyme genes of early biosynthesis of flavonoid in bamboo were identified by bioinfor- matics methods and their expression patterns were analyzed using qPCR. The results showed that the flavonoid content increased at first and then decreased, while that in the functional leaves increased under low temperature and reached significant level at 8 hours. There were a total of 29 members, belonging to three gene families, involved in early biosynthesis of flavonoid in P. edulis, including 20 chalcone synthase genes (PeCHSs), eight chalcone isomerase genes (PeCHIs) and one flavanone-3-hydroxylase gene (PeF3H1), the promoters of these genes all contained regulatory elements in response to low temperature and other abiotic stress responses. The PeCHSs tended to be expressed in roots and leaves, while PeCHIs expressed constitutively. Only the expression trend of PeCHS1 was consistent with the content of flavonoid in P. edulis leaves at different growth stages, while six key enzyme genes (3 PeCHSs, 2 PeCHIs and PeF3H1) were upregulated continuously in functional leaves under low temperature, which was consistent with the change trend of flavonoid content. Therefore, Phyllostachys edulis might respond to low temperature stress by increasing the expression of genes involved in early biosynthesis of flavonoid.