Fig. 4.

Responses to N availability of RGM and 1103P grown as cuttings in hydroponic culture. (A) Transcript levels of SL-related and NIR genes in roots of 1103P (red) and RGM (blue) cuttings during weeks 1 and 2 of N treatment. Dashed lines represent samples from 0N plants and solid lines correspond to HN resupplied plants. Relative normalized expression values are represented as log₂ fold change (LFC) relative to the beginning of the treatment (0 hpt, week 1). Data are presented as means ±SE, n=3 individual plants. Asterisks represent significant differences between 0N and HN conditions for each genotype using Student’s t-test: *P<0.05, **P<0.01, ***P<0.001. (B–G) Fresh weights of different plant organs measured after 35 d of N treatments. Lateral branches (LB) fresh weight per shoot fresh weight (G) were calculated. Data are presented as means ±SE, n=15 individual plants. Letters above the bars indicate significant differences between treatments (i.e. condition × genotype) using a multiple comparison test after Kruskal-Wallis (P<0.05). (H) Germination-stimulant activities of root exudates diluted 1:2. Exudates were collected during the second week of culture from group 1 and group 2 plants. Activities are presented as a percentage relative to the positive control GR24. Data are presented as means ±SE, n=20 (exudates from five individual plants repeated four times). (I) The same root exudates samples were diluted 1:10 and re-plated. Letters indicate significant differences between treatments (i.e. condition × genotype) using a Tukey’s test (P<0.05).