Sequence divergence and loss-of-function phenotypes of S locus F-box brothers genes are consistent with non-self recognition by multiple pollen determinants in self-incompatibility of Japanese pear (Pyrus pyrifolia)
Sequence divergence and loss-of-function phenotypes of S locus F-box brothers genes are consistent with non-self recognition by multiple pollen determinants in self-incompatibility of Japanese pear (Pyrus pyrifolia)
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DOI：
10.1111/j.1365-313x.2011.04752.x
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发表时间：
2011-12-01
期刊：
影响因子：
7.2
通讯作者：
Sassa, Hidenori
中科院分区：
文献类型：
--
作者：
Kakui, Hiroyuki;Kato, Masaki;Sassa, Hidenori
蔷薇科、茄科和车前草科的配子体自交不亲和性（SI）是由位于S位点的至少两个紧密连锁的基因控制的；雌蕊特异性的高多态性S-RNase和花粉特异性的F-box基因（SFB/SLF）。李树（蔷薇科）的自不亲和性被认为是单因子系统的自我识别，因为SFB的功能丧失与自亲和性有关，并且SFB的等位基因分化程度高，与S-RNase相当。相比之下，牵牛花（茄科）表现出多种因素的非自我识别。然而，自识别和非自识别SI系统在不同分类群中的分布尚不清楚。此外，在非自我识别系统中，花粉S的功能丧失表型是未知的。本研究分析了蔷薇科植物梨（Pyrus pyrifolia）的SFBB基因（多个花粉S候选基因）的差异，结果表明，单倍型内差异很大，与S- rnase等位基因多样性相当，而单倍型间差异很低。接下来，我们分析了SFBB1型基因的功能缺失。遗传分析表明，缺乏SFBB1-S4的突变单倍型S4sm花粉被具有其他相容S1的雌蕊拒绝，而被其他非自性雌蕊接受。我们发现S5单倍型编码一个截断的SFBB1蛋白，尽管S5花粉通常被具有S1和其他非自身单倍型的雌蕊接受。这些结果表明，尽管日本梨与李属蔷薇科同属一种，但其在多因子SI系统中具有非自我识别能力。
The S-RNase-based gametophytic self-incompatibility (SI) of Rosaceae, Solanaceae, and Plantaginaceae is controlled by at least two tightly linked genes located at the complex S locus; the highly polymorphic S-RNase for pistil specificity and the F-box gene (SFB/SLF) for pollen. Self-incompatibility in Prunus (Rosaceae) is considered to represent a self recognition by a single factor system, because loss-of-function of SFB is associated with self-compatibility, and allelic divergence of SFB is high and comparable to that of S-RNase. In contrast, Petunia (Solanaceae) exhibits non-self recognition by multiple factors. However, the distribution of self recognition and non-self recognition SI systems in different taxa is not clear. In addition, in non-self recognition systems, a loss-of-function phenotype of pollen S is unknown. Here we analyze the divergence of SFBB genes, the multiple pollen S candidates, of a rosaceous plant Japanese pear (Pyrus pyrifolia) and show that intrahaplotypic divergence is high and comparable to the allelic diversity of S-RNase while interhaplotypic divergence is very low. Next, we analyzed loss-of-function of the SFBB1 type gene. Genetic analysis showed that pollen with the mutant haplotype S4sm lacking SFBB1-S4 is rejected by pistils with an otherwise compatible S1 while it is accepted by other non-self pistils. We found that the S5 haplotype encodes a truncated SFBB1 protein, even though S5 pollen is accepted normally by pistils with S1 and other non-self haplotypes. These findings suggest that Japanese pear has a non-self recognition by multiple factors SI system, although it is a species of Rosaceae to which Prunus also belongs.