A MYB-related transcription factor affects nodule formation in <i>Lotus japonicus</i>

Abstract

The MYB family is one of the largest groups of transcription factors in plants. Our previous microarray data revealed that a MYB-related gene (Ljmybr) was induced upon nodule formation in Lotus japonicus. As shown using real-time PCR, the expression of the Ljmybr in L. japonicus was up-regulated after M. loti infection. To determine the role of Ljmybr in the nodulation process, we created transgenic hairy roots in L. japonicus and then performed Ljmybr overexpression (MYBOX) or RNAi-mediated suppression (MYBRNAi). The results of these experiments indicated that overexpressing Ljmybr accelerated L. japonicus nodulation and increased acetylene reduction activity (ARA) in the nodules. Suppressing Ljmybr (MYBRNAi) delayed nodulation and decreased ARA compared to control suppression (GUSRNAi). Seven days post infection, the expression levels of Nin, Enod40-1 and Enod40-2 were higher in MYBOX-treated nodules and lower in MYBRNAi-treated nodules. We propose that the Ljmybr transcription factor plays a role in regulating nitrogen fixation in L. japonicus.

Stress-regulated elements in Lotus spp., as a possible starting point to understand signalling networks and stress adaptation in legumes

“…A starting point to find an answer should be the study of the relatively few signalling elements reported intervening in flowering, and other circadian-controlled processes, which would be worthwhile being evaluated in relation to biotic and abiotic stresses, i.e. , the putative PHYTOCHROME INTERACTING FACTOR4 ( Lj PIF4, Ono et al, 2010 ) Ljmybr , an MYB-related gene ( Duangkhet et al, 2016 ), clock-associated F-box proteins ( Boycheva et al, 2015 ), NOOT-BOP-COCH-LIKE (NBCL) regulators ( Magne et al, 2018 ) and the flowering regulation gene ( Lj2g3v1989150 , Shah et al, 2020 ).…”