Goldraij Ariel, Kondo Katsuhiko, Lee Christopher B, Hancock C Nathan, Sivaguru Mayandi, Vazquez-Santana Sonia, Kim Sunran, Phillips Thomas E, Cruz-Garcia Felipe, McClure Bruce
CIQUIBIC, Departamento de Quimica Biologica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba, Argentina.
Nature. 2006 Feb 16;439(7078):805-10. doi: 10.1038/nature04491.
Pollen-pistil interactions are crucial for controlling plant mating. For example, S-RNase-based self-incompatibility prevents inbreeding in diverse angiosperm species. S-RNases are thought to function as specific cytotoxins that inhibit pollen that has an S-haplotype that matches one of those in the pistil. Thus, pollen and pistil factors interact to prevent mating between closely related individuals. Other pistil factors, such as HT-B, 4936-factor and the 120 kDa glycoprotein, are also required for pollen rejection but do not contribute to S-haplotype-specificity per se. Here we show that S-RNase is taken up and sorted to a vacuolar compartment in the pollen tubes. Antibodies to the 120 kDa glycoprotein label the compartment membrane. When the pistil does not express HT-B or 4936-factor, S-RNase remains sequestered, unable to cause rejection. Similarly, in wild-type pistils, compatible pollen tubes degrade HT-B and sequester S-RNase. We suggest that S-RNase trafficking and the stability of HT-B are central to S-specific pollen rejection.
花粉与雌蕊的相互作用对于控制植物交配至关重要。例如，基于S-核酸酶的自交不亲和性可防止多种被子植物物种的近亲繁殖。S-核酸酶被认为作为特异性细胞毒素发挥作用，抑制具有与雌蕊中某一S-单倍型相匹配的S-单倍型的花粉。因此，花粉和雌蕊因子相互作用以防止亲缘关系较近的个体之间交配。其他雌蕊因子，如HT-B、4936-因子和120 kDa糖蛋白，对于花粉排斥也是必需的，但本身并不赋予S-单倍型特异性。在此我们表明，S-核酸酶被摄取并分选到花粉管中的一个液泡区室。针对120 kDa糖蛋白的抗体标记该区室膜。当雌蕊不表达HT-B或4936-因子时，S-核酸酶被隔离，无法导致排斥反应。同样，在野生型雌蕊中，亲和花粉管会降解HT-B并隔离S-核酸酶。我们认为，S-核酸酶的运输和HT-B的稳定性对于S-特异性花粉排斥至关重要。
