Abstract: Tenuazonic acid is one of the most important toxins from Alternaria.In the appropriate concentration,which no harm to the Rose but have repellent effect to aphids.Two strains of Alternaria,named 0363 and 0645,were isolated from the leaves of Rosa chinensis.Comparison of cultured characters and the sequence analysis of 18s and ITS genes and microscopic features of these two strains,0363 was identified as Alternaria alternate.Keissler,and 0645 was identified as Alternaria tenuissima through the morphology and molecular identification.Toxins were extracted by organic solvent and determined by HPLC analysis.Results showed that TeA was detected in crude extracts of two strains.The results of this research provided the experimental materials and theoretical basis for diseases and pests prevention of Rosa chinensis,and for mechanism research of indirect insect and host plants mediated interactions.

Key words: Rosa chinensis, alternaria, identification, toxin, disease and pest interactions