Fig. 6. NSP1 and NSP2 promote the expression of LysM-type receptors allowing LCO recognition.

Heatmaps representing the expression of genes encoding the common symbiosis signaling pathway and LysM-type receptor-like kinases in wild-type plants under N- and/or P-starvation, as well as in nsp mutants under nutrient deficient conditions and in NSP overexpression lines under nutrient-replete conditions in M. truncatula (a) and barley (b). +P−N, −P + N and -P-N represent the expression of these genes in wild-type plants under −N or/and −P conditions in comparison to +P + N conditions. nsp mutant columns show the expression of these genes in nsp mutants compared to wild type under nutrient-deficient conditions, while NSPox columns show NSP overexpression roots compared to wild type under nutrient-replete conditions. c Expression of barley RLK10 in wild type and d14l mutant roots. Plants were grown in nutrient deficient or sufficient conditions for 3 weeks. n = 4 biologically independent samples, ±s.e.m.; **indicates p < 0.01, *indicates 0.01 < p < 0.05, measured using a Student’s t-test (one-tailed, two-sample equal variance). d Induction of barley RLK10 by 5DS and KARs. Wild type, d14l-1 and nsp2-2 mutant plants were grown under repressive P-conditions and pretreated for 2 days on solid media containing 1 μM 5-deoxystrigol (5DS) or a mixture of 1 μM karrikin 1 and karrikin 2 (KARs). n = 4 biologically independent samples, ±s.e.m. *indicates 0.01 < p < 0.05, measured using a Student’s t-test (one-tailed, two-sample equal variance). e Root-length colonization of barley rlk10, rlk2, and rlk2/rlk10 double mutants grown under P-limited conditions, measured at 7 weeks post inoculation. The RLK10 mutation in the rlk2/rlk10 double mutant is equivalent to rlk10-1. n = 5–8 biologically independent plants. Total: total colonization; A: arbuscules. p-values for colonization levels were determined by a one-sided Wilcoxon test. **p < 0.01; *0.01 < p < 0.05.