Regulation of flowering and protective enzyme gene expression in Mikania micrantha by exogenous hormone CPPU

  Objective  Mikania micrantha is a class I alien invasive harmful plant, which relies on seeds to spread rapidly, causing significant ecological and economic losses. By exploring the mechanism of N-(2-chloro-4-pyridyl)-N-phenylurea (CPPU) on the reproductive regulation of M. micrantha, a new strategy was provided to curb the trend of M. micrantha’s rapid spread.

  Method  The number of inflorescences and florets of M. micrantha treated with CPPU was counted anatomically. The mechanism of inhibition of flowering by CPPU was analyzed by RNA-seq, and determined the enzyme activities of protective enzymes in flowering stage of M. micrantha.

  Result  (1) CPPU could effectively inhibit the flower formation of M. micrantha, with the increase of CPPU concentration, the number of inflorescences and florets decreased. After being treated with 5 mg/L CPPU, the number of inflorescences and florets decreased by 34.50% and 36.70%, respectively. There was no flower after 75 mg/L of CPPU treatment. (2) Transcriptome analysis revealed differential regulation of protective enzyme genes, it was found that, after being treated with 75 mg/l CPPU, a large number of DEGs related to pod and PAL were up-regulated; (3) the results of the protective enzyme activity indicated that CPPU treatment decreased the enzyme activity of PAL (phenylalanine ammonia-lyase), POD (peroxidase) and CAT (catalase), but increased the protective enzyme activity of PPO (polyphen oloxidase tyrosinase phenlase).

  Conclusion  75 mg/L of CPPU can control the expression of protective enzyme gene of M. micrantha, which cause membrane lipid peroxidation damage and inhibit the flowering process, thus it can effectively control the reproduction and spread of M. micrantha.