摘要 : Successful cyst nematode parasitism depends on the formation and maintenance of feeding sites (syncytia) in host roots, and these processes are highly regulated by the interaction between the cyst nematode and the host. Using an i... 展开 Successful cyst nematode parasitism depends on the formation and maintenance of feeding sites (syncytia) in host roots, and these processes are highly regulated by the interaction between the cyst nematode and the host. Using an integrated research approach and the <i>Arabidopsis-Beta vulgaris</i> (sugar beet) cyst nematode (<i>Heterodera schachtii</i>) pathosystem, we have determined that the two <i>Arabidopsis</i> basic helix-loop-helix transcription factors bHLH25 and bHLH27 positively influence cyst nematode parasitism. Promoter studies indicated that as early as 1day post-inoculation, both transcription factor genes were upregulated in developing syncytia, whereas in non-infected plants, these two promoters were not found to be active in the same cells. By using yeast two-hybrid analyses and bimolecular fluorescence complementation assays, we documented that the two bHLH transcription factors can dimerize <i>in planta</i>. Transgenic <i>Arabidopsis</i> plants overexpressing either one or both of the <i>bHLH</i> genes exhibited altered morphology of roots and shoots, as well as an increased susceptibility to <i>H. schachtii</i>. <i>bhlh25</i> or <i>bhlh27</i> single mutants were without strong phenotypes, presumably because of functional redundancies in this gene family. However, the <i>bhlh25 bhlh27</i> double mutant was less susceptible to <i>H. schachtii</i>, confirming an important conducive role of the co-expression of both transcription factor genes for cyst nematode parasitism. Our results document an example of pathogen-induced ectopic co-expression of two regulatory genes to enhance pathogen success, although these transcription factors apparently do not function in concert in non-infected plants. This is an intriguing biological phenomenon that highlights the complexity of obligate biotrophic plant-pathogen interactions, like those of cyst nematodes. 收起