Figure 4

DNA dsb severely affects development in the atrad21.1 atrad21.3 double mutant. (A) atrad21.1 atrad21.3 displays the severest DNA dsb damage induced developmental arrest. The highest frequency of seedlings arrested at the early stages of development (0 and 1 true leaf) in the atrad21.1 atrad21.3 double mutant illustrates its high hypersensitivity to DNA dsb damage. At 100 Gy, this frequency is higher in the double mutant than in the single mutants and Col; only at 150 Gy does this frequency, in atrad21.1 and the double mutant, become similar. At 100 Gy, the frequency of seedlings with 0 and 1 true leaf, in Col and in atrad21.3, is similar; but at 150 Gy it becomes higher in atrad21.3. (B) atrad21.1 atrad21.3 and atrad21.1 are significantly different from Col (100 Gy). Medians and the Mann-Whitney non-parametric test (p value (p)<0.01, 2-tailed hypothesis) show that DNA dsb induces severe development arrest in atrad21.1 atrad21.3, and less so in atrad21.1. Both mutants are significantly different from Col (100 Gy and 150 Gy). Only at 150 Gy is atrad21.3 also significantly different from Col. Error bars: standard deviation of the data (to the median). Black asterisk: significant difference (0<p<0.01), (Col versus atrad21.1; 100 Gy; U=2026; p=0.00652). Grey asterisk: significant difference (p=0) at 100 Gy: (Col versus atrad21.1; U=726.5); and at 150 Gy: (Col versus atrad21.1; U=5278.5), (Col versus atrad21.3; U=4712), (Col versus atrad21.1 atrad21.3; U=2920.5). atrad21.3 is not significantly different from Col at 100 Gy (U=2635; p=0.06432). Figure 4(A and B): true leaves were counted in GM germinated seedlings, 15 days after the irradiation of imbibed seeds with 0 Gy (mock irradiation) or 100 Gy or 150 Gy (γ-rays; 3.25 Gy/minute; source: Cs137). Col - wild-type Columbia-0. Frequencies and medians were calculated with the data from the compiled data tables (Additional file 1: Table S4).