Laboratory of Plant Breeding, Wageningen University, Wageningen, 6700 AJ, The Netherlands.
Plant Cell. 2009 Oct;21(10):3368-78. doi: 10.1105/tpc.109.070334. Epub 2009 Oct 23.
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.
一些种间和种内杂交可能导致后代的活力或可育性降低，这通常是由于两个或多个基因座之间的相互作用导致的遗传不相容性。杂种坏死是一种合子后遗传不相容性，表型上表现为植物上的坏死病变。我们观察到生菜（Lactuca sativa 和 Lactuca saligna）种间杂种中的杂种坏死与对霜霉病的抗性有关。分离分析表明，两个相互作用的基因座上的特定等位基因组合是负责的。等位基因相互作用有两个后果：（1）一种与温度有关的定量自身免疫反应，导致坏死病变、致死性和对 otherwise virulent Bremia lactucae 菌株的定量抗性；（2）一种对 otherwise avirulent Bremia lactucae 菌株的定性温度独立的抗性。我们通过瞬时表达和沉默实验证明，两个相互作用的基因之一是 Rin4。在拟南芥中，RIN4 已知与多个 R 基因产物相互作用，它们的相互作用导致对 Pseudomonas syringae 的超敏抗性。在生菜中 Rin4 的坏死诱导等位基因上进行的定点突变研究表明，三个残基对杂种坏死至关重要。
