Effect of Soybean Coumestrol on Bradyrhizobium japonicum Nodulation Ability, Biofilm Formation, and Transcriptional Profile

We investigated the biofilmforming ability and transcriptome-level changes of B. japonicum

Hae-In Lee; Jin-Hwan Lee; Ki-Hun Park; Dipen Sangurdekar; Woo-Suk Chang

2012

Scholarcy highlights

  • Flavonoids, secondary plant metabolites which mainly have a polyphenolic structure, play an important role in plant-microbe communications for nitrogen-fixing symbiosis
  • We hypothesized that pretreatment of B. japonicum with coumestrol may enhance the soybean nodulation
  • The overall pattern of the nodule distribution on the primary root is similar among all samples, and the most nodules have been formed near the initial root tip position, suggesting that there is no difference in timing and duration of nodule development by pretreatment of B. japonicum with coumestrol, even at the high concentration
  • We showed that soybean coumestrol enhanced the nodulating ability of B. japonicum on soybean roots, and we attempted to find out the molecular mechanisms of the nodulation enhancement at the transcriptional level using an oligonucleotide microarray platform developed previously
  • Our initial transcriptomic data showed no induction of nod genes, we were able to confirm the low-level induction of nodD1 and nodABC by quantitative reverse transcription-PCR, which could be the most sensitive method for the detection of low levels of mRNA
  • When the bacterium was incubated in 20 μM coumestrol for 24 h, a total of 371 genes were differentially expressed at a 2-fold cutoff with a q value of less than 5%
  • Our studies examined the antimicrobial activities of coumestrol isolated from soybean roots and its effects on the nodulation, biofilm formation, and transcriptome of B. japonicum
  • Our transcriptomic and mutation studies indicate that NfeD-like protein is involved in coumestrol-mediated soybean nodulation

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