Whole seedlings of wild type (4d) and atm mutants (4d) have been analyzed after a gamma ray irradiation of 0.75h, 1.5h, 3h & 5h (time course). Roots of wt (4d), atm (3d) and atr (4d) mutants have been analyzed after a 1h irradiation.

Ataxia Telangiectasia Mutated (ATM), encodes a large protein with a phosphatidylinositol 3-kinase (PI3K)-like domain at the C terminus (reviewed by Rotman and Shiloh, 1998). PI3K-related proteins make up a large family of Ser-Thr protein kinases, numerous members of which are involved in the regulation of cell cycle progression, responses to DNA damage, and the maintenance of genomic stability (Hoekstra, 1997). AtATM plays an essential role in meiosis and in the somatic response to DNA damage in plants, similar to the function of ATM in mammals and other eukaryotes.
Ataxia telangiectasia-mutated and Rad3-related (ATR) plays a central role in cell-cycle regulation, transmitting DNA damage signals to downstream effectors of cell-cycle progression.