Table 1.

DNA double-strand break (DSB) repair machinery^a and its possible involvement in T-DNA Integration

Budding yeast	Arabidopsis	Proposed function	Requirement for T-DNA integration	References
Non-homologous end joining (NHEJ)
Ku70	AtKU70	The Ku70-Ku80 heterodimer detects and juxtaposes the DSB ends	Yes (yeast)	[33]
Ku80	AtKU80		Yes/No (plants)b	[36–38]
Mre11	AtMRE11	The Mre11-Rad50-Xrs2 (MRX) complex processes the DSB ends	Yes (yeast)	[33]
Rad50	AtRad50		Yes (yeast)	[33]
Xrs2	ND		Yes (yeast)	[33]
Lig4	AtLIG4	The Lig4-Lif1 complex ligates the DSB ends	Yes (yeast), Yes/No (plants)b	[33,36,39]
Lif1	AtXRCC4		ND
Homologous recombination (HR)
Rad51	AtRAD51	Facilitates strand invasion	Yes (yeast)	[34]
Rad52	AtRAD52	Helps to load Rad51 onto ssDNA	Yes (yeast)	[34]
Mre11	AtMRE11	The Mre11-Rad50-Xrs2 (MRX) complex processes the DSB ends.	No (yeast)	[34]
Rad50	AtRAD50		No (yeast)	[34]
Xrs2	ND		No (yeast)	[34]
Rad54	AtRAD54	Facilitates strand invasion	Enhances gene targeting in plantsc	[77]

ND, not determined; ss, single-stranded.

^aOnly major DSB repair factors involved in NHEJ and HR are listed.

^bNot conclusive due to conflicting results between different studies.

^cExpression of the yeast Rad54 in Arabidopsis enhances gene targeting (i.e., HR-mediated T-DNA integration) by one to two orders of magnitude [77].