Consistent with its biochemical role, TvQR1 gene expression is rapidly up regulated in T. versicolor root tips exposed to either maize selleck products or Arabidopsis root exudates containing active HIFs, DMBQ or the non HIF juglone. By contrast, up regulation of TvPirin in root tips only occurs in re sponse to DMBQ and Arabidopsis root exudates. Most identified HIFs are quinones like DMBQ, which are known to be abundant in Inhibitors,Modulators,Libraries plant exudates and have also been associated with allelopathic effects and defense against pathogens. At concentrations below 10 4 M, quinone HIFs induce haustorium development in parasitic plants. However, at concentrations between10 4 M and 10 3 M, they impart the negative effects of oxidative stress to parasitic plants that result in root necrosis and a reduction in the frequency of haustor ium formation.
Further underscoring this Inhibitors,Modulators,Libraries quinone toxicity is the enrichment of transcripts involved in oxidative stress and detoxification pathways in T. versicolor root tips following exposure to DMBQ or host root exudates. Like DMBQ, juglone is a well known allelopathic compound present copiously in root exudates of the black walnut tree, but unlike DMBQ, juglone lacks the haustorium inducing capability. The fact that juglone is a better substrate for TvQR1 than DMBQ correlates with the faster and stronger up regulation of TvQR1 expression in T. versicolor root tips upon juglone exposure. The only non quinone Inhibitors,Modulators,Libraries HIF known to date is the flavonoid peonidin. Peonidin belongs to the anthocyanin class of compounds present in red colored flowers and fruits that act as potent antioxidants by scavenging free radicals, and play various roles in plant development and stress protection.
Although peonidin is a HIF as potent as DMBQ for T. versicolor, its role in the regulation of TvQR1 and TvPirin gene expression during haustorium development has not yet been investigated. Furthermore, the availability of peonidin, a non toxic HIF, DMBQ, a toxic HIF, Inhibitors,Modulators,Libraries and juglone, a toxic non HIF, offers the opportunity to utilize these three Inhibitors,Modulators,Libraries chemicals to de couple the two seemingly intertwined pathways triggered by the quinone HIFs namely the oxidative stress response and haustorium organogenesis. To understand how TvPirin and TvQR1 contribute to the perception of various phytochemicals present in the rhizosphere and, thus, to the initiation of haustorium development, it is essential to survey their patterns of polymorphism in natural populations of T.
versicolor. Since so far only a single allele of each of these two genes has been reported, we examined the pattern of nucleotide polymorphism of TvQR1 and TvPirin by using 20 T. versicolor individual plants from natural populations of the Northern Californian grasslands. We found strikingly higher allelic diversity in TvQR1 compared Ivacaftor purchase to TvPirin, with the highest non synonymous substitution rate in the catalytic domain of the TvQR1 protein.