Fig. 1: Natural variation of the LR response to low N and GWA mapping of YUC8.

a Representative A- and T-allele accessions of A. thaliana that show weak (Co, Ty-0, Edi-0), intermediate (Col-0), and strong (Par-3, Uod-1, Ven-1) LR elongation response to low N availability. HN, high N (11.4 mM N); LN, low N (0.55 mM N). b Reaction norms and phenotypic variation of average LR length of 200 natural accessions of A. thaliana under different N supplies. Purple diamonds represent the means of lateral root lengths for 200 accessions under each N treatment. c Frequency distribution of LR response to N availability (i.e., the ratio between LN and HN) for 200 natural accessions. d Manhattan plot for SNP associations with LR response to low N performed with vGWAS package. Negative log₁₀-transformed P values from a genome-wide scan were plotted against positions on each of the five chromosomes of A. thaliana. Chromosomes are depicted in different colors (I to V, from left to right). The red dashed line corresponds to the Benjamini and Hochberg false-discovery rate level of q < 0.05 adjusted for multiple testing. e The 20-kb-long genomic region concentered on the lead GWA peak for LR response to low N, and genes located within this region. f–h Appearance of plants (f), primary root length (g), and average LR length (h) of wild-type (Col-0) and two yuc8 mutants. Bars represent means ± SEM. Number of individual roots analyzed in HN/LN: n = 20/19 (Col-0), 15/17 (yuc8-1), 20/20 (yuc8-2). i–k Appearance of plants (i), primary root length (j), and average LR length (k) of wild-type (Col-0) and yucQ mutant after 9 days on HN or LN. Bars represent means ± SEM. Number of individual roots analyzed in HN/LN: n = 20/21 (Col-0) and 22/17 (yucQ). Different letters in (g, h) and (j, k) indicate significant differences at P < 0.05 according to one-way ANOVA and post hoc Tukey test. Scale bars, 1 cm.