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Updated: May 20, 2026

Lateral Root Inducible System in Arabidopsis and Maize
Published on: January 14, 2016
Additional cause for reduced JA-Ile in the root of a Lotus japonicus phyB mutant
Tamaki Shigeyama1, Akiyoshi Tominaga, Susumu Arima
1Department of Environmental Sciences, Faculty of Agriculture, Saga University, Honjyo-machi, Saga, Japan.
Abstract:
Light is critical for supplying carbon for use in the energetically expensive process of nitrogen-fixing symbiosis between legumes and rhizobia. We recently showed that root nodule formation in phyB mutants [which have a constitutive shade avoidance syndrome (SAS) phenotype] was suppressed in white light, and that nodulation in wild-type is controlled by sensing the R/FR ratio through jasmonic acid (JA) signaling. We concluded that the cause of reduced root nodule formation in phyB mutants was the inhibition of JA-Ile production in root. Here we show that the shoot JA-Ile level of phyB mutants is higher than that of the wild-type strain MG20, suggesting that translocation of JA-Ile from shoot to root is impeded in the mutant. These results indicate that root nodule formation in phyB mutants is suppressed both by decreased JA-Ile production, caused by reduced JAR1 activity in root, and by reduced JA-Ile translocation from shoot to root.
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