《Nature》：植物避免同系繁殖的分子机制

生物谷

自我不匹配性，是许多开花植物用来通过拒绝“自己的”（不匹配的）花粉而防止同系繁殖（自花授粉）的一种重要的由基因控制的过程。在植物中，程序化的细胞死亡（与动物程序化的细胞死亡有些相似）被用来以一种精确控制的方式消灭不想要的细胞。

现在，研究发现，自我不匹配性的识别和程序化的细胞死亡这两个体系在罂粟植物中是协同发挥作用的。当来自柱头的S-蛋白识别出不匹配的花粉并诱发自我不匹配排斥时，程序化的细胞死亡被诱发，使花粉管的生长受到抑制。

在另一项研究中，研究人员在矮牵牛植物中识别出了捉摸不定的花粉特性基因，即花粉S- 基因。在自我不匹配性的基因控制中的另一主要基因为雌蕊特性基因S-Rnase基因，它的性质以前就被明确弄清。由于两个S-基因现在都可以人为操纵，所以预计关于自我不匹配性过程的更多细节问题很快将会弄明白。

Nature 429, 302 - 305 (20 May 2004); doi:10.1038/nature02523

Identification of the pollen determinant of S-RNase-mediated self-incompatibility

PAJA SIJACIC¹, XI WANG^2,*, ANDREA L. SKIRPAN², YAN WANG³, PETER E. DOWD², ANDREW G. MCCUBBIN^2,*, SHIHSHIEH HUANG⁴ & TEH-HUI KAO^1,2,3

¹ Integrative Biosciences Graduate Degree Program, The Pennsylvania State University, 403 Althouse Laboratory, University Park, Pennsylvania 16802, USA
² Department of Biochemistry and Molecular Biology, The Pennsylvania State University, 403 Althouse Laboratory, University Park, Pennsylvania 16802, USA
³ Intercollege Graduate Program in Plant Physiology, The Pennsylvania State University, 403 Althouse Laboratory, University Park, Pennsylvania 16802, USA
⁴ Mystic Research, Monsanto Company, 62 Maritime Drive, Mystic, Connecticut 06355, USA
* Present addresses: Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan 48109, USA (X.W.); School of Biological Sciences and Center for Reproductive Biology, Washington State University, Pullman, Washington 99164, USA (A.G.M.)

Correspondence and requests for materials should be addressed to T.-h.K. (txk3@psu.edu).

Many flowering plants have adopted self-incompatibility mechanisms to prevent inbreeding and promote out-crosses. In the Solanaceae, Rosaceae and Scrophulariaceae, two separate genes at the highly polymorphic S-locus control self-incompatibility interactions: the S-RNase gene encodes the pistil determinant and the previously unidentified S-gene encodes the pollen determinant. S-RNases interact with pollen S-allele products to inhibit the growth of self-pollen tubes in the style. Pollen-expressed F-box genes showing allelic sequence polymorphism have recently been identified near to the S-RNase gene in members of the Rosaceae and Scrophulariaceae; but until now have not been directly shown to encode the pollen determinant. Here we report the identification and characterization of PiSLF, an S-locus F-box gene of Petunia inflata (Solanaceae). We show that transformation of S₁S₁, S₁S₂ and S₂S₃ plants with the S₂-allele of PiSLF causes breakdown of their pollen function in self-incompatibility. This breakdown of pollen function is consistent with 'competitive interaction', in which pollen carrying two different pollen S-alleles fails to function in self-incompatibility. We conclude that PiSLF encodes the pollen self-incompatibility determinant.