Fig 4. JA levels [nmol/g FW] measured in root and shoot systems of L. japonicus plants grown with a nitrogen source or with rhizobia.

Results show six independent plant series grown under three different growth conditions, i.e. two series per growth condition. T-0 marks the beginning of the experiments when 5-week-old plants were transferred from soil to the aeroponic tank. Subsequent samples were collected in weekly intervals: T-1 after one week, T-2 after two weeks, T-3 after three weeks, T-4 after four weeks. In the case of the series grown without nitrogen, infection with M. loti strain TONO took place at T-0. At least five plants were harvested per time point; three technical replicates were analysed based on their combined root- or shoot systems, respectively. The data were evaluated using R [46] and plotted using ggplot2 (version 2.2.1, [47]). The analytical error is too large to allow the detection of statistically significant differences (Mann Whitney U) between the series.