Table 1.

Cloned susceptibility genes from naturally occurring mutants

Role as a effector target	Gene	Plant species	Encoded protein	Pathogen	Reported pleiotropic phenotype	References
Negative regulator	MLO orthologues	Barley	Transmembrane protein	Blumeria graminis	Early senescence and axenic cell death	Büschges et al. (1997)
		Tomato		Oidium neolycopersici	Not reported	Bai et al. (2008)
Susceptibility factor	Genes encoding isoforms of eIF4E and eIF4G	Several species	Translation initiation factor	Potyviridae	Not reported	Diaz-Pendon et al. (2004) Robaglia and Caranta (2006)
	Xa5	Rice	Transcription factor IIA-γ	Xanthomonas oryzae	Not reported	Iyer-Pascuzzi and McCouch (2007)
	Xa13	Rice	Membrane-localized protein	X. oryzae	Pollen abortion	Chu et al. (2006); Yang et al. (2006); Sugio et al. (2007)