Rin4 causes hybrid necrosis and race-specific resistance in an interspecific lettuce hybrid.
Some inter- and intraspecific crosses may result in reduced viability or sterility in the offspring, often due to genetic incompatibilities resulting from interactions between two or more loci. Hybrid necrosis is a postzygotic genetic incompatibility that is phenotypically manifested as necrotic lesions on the plant. We observed hybrid necrosis in interspecific lettuce (Lactuca sativa and Lactuca saligna) hybrids that correlated with resistance to downy mildew. Segregation analysis revealed a specific allelic combination at two interacting loci to be responsible. The allelic interaction had two consequences: (1) a quantitative temperature-dependent autoimmunity reaction leading to necrotic lesions, lethality, and quantitative resistance to an otherwise virulent race of Bremia lactucae; and (2) a qualitative temperature-independent race-specific resistance to an avirulent race of B. lactucae. We demonstrated by transient expression and silencing experiments that one of the two interacting genes was Rin4. In Arabidopsis thaliana, RIN4 is known to interact with multiple R gene products, and their interactions result in hypersensitive resistance to Pseudomonas syringae. Site-directed mutation studies on the necrosis-eliciting allele of Rin4 in lettuce showed that three residues were critical for hybrid necrosis.
Laboratory of Plant Breeding, Wageningen University, Wageningen, 6700 AJ, The Netherlands. marieke.jeuken@wur.nl
Marieke J W
MJ
Jeuken
Ningwen W
NW
Zhang
Leah K
LK
McHale
Koen
K
Pelgrom
Erik
E
den Boer
Pim
P
Lindhout
Richard W
RW
Michelmore
Richard G F
RG
Visser
Rients E
RE
Niks
D002678:Chimera / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D007113:Immunity, Innate / Q000235:genetics / Q000502:physiology; D018545:Lactuca / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009336:Necrosis / Q000235:genetics*; D009868:Oomycetes / Q000472:pathogenicity*; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000502:physiology*; D013696:Temperature
D010940:Plant Proteins