Transcriptomic profiles of nodule senescence in <i>Lotus japonicus</i> and <i>Mesorhizobium loti</i> symbiosis

Abstract

Nodule senescence is a complex developmental process during which essential nutrients are recycled. In order to understand the regulatory mechanism, transcript-profiling analysis during nodule senescence was performed in the Lotus japonicus-Mesorhizobium loti symbiosis. Microarray data showed significantly up-regulated expressions in 641 genes out of a total of 20,165 genes during nodule senescence, and down-regulated expressions were observed in 416 genes. These up-regulated genes during senescence were related to cell wall/membrane/envelope biogenesis and extracellular structures. Down-regulated genes were mainly responsible for defense mechanisms. We classified senescence up-regulated genes in two clusters. Genes in cluster 1 were induced at senescence specific stage and those in cluster 2 were induced from nitrogen fixation stage and expressed until nodule senescence. The genes in cluster 1 included typical marker for senescence like gene for heat shock protein. Four hundred sixteen down-regulated genes during nodule senescence were also classified in two clusters, cluster 3 and cluster 4. These genes corresponded to metabolisms for amino acid and plant hormones which are necessary for growth and cell division during nodule development and nitrogen fixation. These results provide the comprehensive data source for investigation of molecular mechanisms underlying nodule senescence in Lotus japonicusMesorhizobium loti symbiosis.

Drought‐induced senescence of Medicago truncatula nodules involves serpin and ferritin to control proteolytic activity and iron levels

“…a–d). These results are in agreement with previous reports suggesting that elevation of proteolytic activity during nodule senescence results in nodule protein and lb degradation (Pladys & Vance, ; Chungopast et al ., ). It seems logical to propose that the nutrients obtained from the protein degradation are recycled and used as a nitrogen source to sustain plant growth.…”

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

“…Many researchers have performed transcriptome or RNA-seq analyses in L. japonicus and identified genes upregulated after M. loti infection (Chungopast et al 2014;Handa et al 2015;Kouchi et al 2004). From these data, we found that the Ljmybr transcription factor (chr4.CM0004.2240.r2.d) was up-regulated in roots after M. loti infection.…”

“…Previously, researchers performed transcriptome or RNA-seq analysis and identified many upregulated genes in Lotus japonicus nodules after Mesorhizobium loti infection (Chungopast et al 2014;Handa et al 2015;Kouchi et al 2004). From these data, we found one upregulated gene, MYB-related transcription factor (Ljmybr).…”

Ectopic or Over-Expression of Class 1 Phytoglobin Genes Confers Flooding Tolerance to the Root Nodules of Lotus japonicus by Scavenging Nitric Oxide

“…We have reported that nodule senescence in the Ox1 line is delayed [33]. Quantification by qRT-PCR showed that the expression of all three nodule senescence marker genes (coding a heat shock protein, an osmotin precursor, and cysteine protease Cyp2; [33,49,50]) was increased in flooded nodules relative to untreated nodules of WT and 96642; the increase was much lower or absent in the nodules of Ox1 and Afx1 (Figure 3).…”