Figure 6

C-NHEJ versus HR associated atrad21 DNA dsb damage hypersensitivity. Comparison of the DNA dsb damage induced phenotypes of the C-NHEJ associated atku80 mutant versus the HR associated rad21 mutations. Imbibed seeds of mutants homozygous for the atku80 mutant allele (atku80 atrad21.1 and atku80) are extremely hypersensitive to DNA dsb; furthermore, they are more hypersensitive to DNA dsb than the atrad21.1 atrad21.3 double mutant and even more so than the atrad21.1 single mutant; this has been confirmed in different experimental replicas. The blown up (2× magnification) seedlings’ pictures show atku80 and atku80 atrad21.1 exhibiting a more severe hypersensitivity to DNA dsb damage than atrad21.1 atrad21.3. While some atrad21.1 atrad21.3 seedlings are still able to form some true leaves (a seedling with nine small true leaves is shown) after irradiation with 100 Gy of ionising radiation, atku80 and atku80 atrad21.1 development is arrested at an earlier stage (seedlings with no true leaves or with one incipient true leaf). The atrad21.1 seedlings exhibit the least hypersensitive phenotype of all four mutants. Imbibed seeds were exposed to 100 Gy of ionising radiation (3.25 Gy/minute; source: Cs137); 0 Gy were not exposed to ionising radiation. The seedlings germinated from the irradiated imbibed seeds were photographed 23 days after the exposure to ionising radiation. Col - wild-type Columbia-0 plant; Ws - wild type Wassilewskija-1 plant.