Molecular genetical analysis of the two locus self incompatibility in the grasses (Poaceae)

禾本科植物的自交不亲和性（self-incompatibility，SI）受两个非连锁位点Sand Z的配子体控制。本研究旨在建立野生大麦（Hordeum bulbosum，2x）自交不亲和性的遗传基础，并克隆SI基因。基本遗传分析包括植物系的杂交试验、SI基因型的确定、大作图群体的产生、与SI基因座紧密连锁的DNA标记的鉴定等。在S基因的克隆方面，采用基于AFLP的mRNA指纹（AMF）方法从雌蕊和花药中寻找S基因型特异转录本。通过AMF分析，从雌蕊和花药转录本中检测到几十个S特异片段。克隆片段并进行RFLP分析以检查与S位点的连锁。到目前为止，已经证实了几个克隆与S位点紧密连锁。利用S连锁克隆构建了S位点附近的详细遗传图谱。在S基因座和一些克隆之间没有发现重组，表明这些克隆是S基因的候选者。候选克隆的表达模式和序列多态性应进行详细分析，以检查它们是否是S基因。还需要进一步建立球孢菌的转化体系，以证明候选基因是S特异性的决定基因

The self-incompatibility (SI) in the grasses (Poaceae) is gametophytically controlled by two unlinked loci, Sand Z, The aim of this project is to establish the genetic basis of the SI in wild barley, Hordeum bulbosum (2x) and to clone the SI gene(s). The basic genetical analysis involves crossing experiments of plant lines, determination of SI genotypes, production of large mapping populations, identification of DNA markers closely linked to the SI loci, etc. Toward the,, cloning of the S gene, the AFLP-based mRNA fingerprinting (AMF) method was employed to search S genotype-specific transcripts from pistils and anthers at anthesis. By the AMF analysis, dozens of S specific fragments were detected from both the pistil and anther transcripts. The fragments were cloned and subjected to the RFLP analysis to examine linkage to the S locus. Several clones have so far been confirmed for the close linkage to the S locus. The S-linked clones were used to construct a detailed genetic map around the S locus. No recombination was found between the S locus and some of the clones, indicating that those clones are candidates of the S gene. The expression pattern and sequence polymorphism of the candidate clones should be analyzed in detail to examine whether they are the S gene or not. It is also necessary to develop the transformation system for H bulbosum to demonstrate that the candidate gene is the determinant of S specificity