Positively Allelopathic Effect And It's Molecular Mechanism Of Achyranthes Bidentata Blume. Mediated By Continuou Cropping Many Yeas Soils

Based on the investigation of a positive allelopathic effect of Achyranthes bidentata Blume. in a continuous cropping system in Henan province, an experiment was conducted to study the effect and influence of continuous cropping soils of Achyranthes bidentata Blume..First,the allelochemicals in the rhizospheric soil sampled from the field of continuously cropped A. bidentata Blume. plants were extracted by water and organic solvent. The results from the bioassay in Petri dishes showed that the promotion effect of the extracts on the growth of Lactuca sativa was significant, the effect rates (ERs) of the treatments were more than 25%. Soils of different continuous cropping years,especially the treatments of water extraction were more than 100%. This result implying that the allelochemicals especially from the water extracts might contain plant activators to promote the growth of L. sativa.To further understand the mechanism of the growth promotion by the extracts, subtractive hybridization suppression (SSH) was used to investigate gene expression profiles of A. bidentata Blumem treated with the extracts. Ten upregulated genes from SSH-cDNA library were sequenced and assigned. According to the function category, the identified genes were related to the elementary metabolism, flavonoids and phytosterol synthesis.Proteomics were employed to confirm the molecular mechanism of growth promotion by the extracts. The result showed that 25 proteins changed in the expression abundances in the treated plants compared with control, of which 15 were up-regulated and 10 down-regulated. Based on the functions of the identified proteins, these protains were mainly related to nutrition absorption and metabolism, Secondary metabolism and resistance, signal transduction, as well as nucleotides and protein synthesis.Based on analysis of differential gene expressionon and protein synthesis,by SSH and proteomics, The findings suggested that the former crop A.bidentata Blume. formed allelochemicals,this allelochemicals may be terpenes or flavonoids,and liberate those allelochemicals to its growth environment (by thansformation and amplication effect of microbia) , These may excitate some signal transduction system and induce gene'expressionon and protein synthesis, regulate the hormones level in the organism. All these changes may process the cell division and growth of A.bidentata Blume, and proceed the nutrition absorption and the synthetics allocation. Sequentially, the growth of A.bidentata Blume is regulated, its root underground grow thicker and longer, So the medicine components of A.bidentata Blume are improved.