Molecular characterization of the genomic region linked with apomixis in Pennisetum/Cenchrus
Molecular characterization of the genomic region linked with apomixis in Pennisetum/Cenchrus
复制标题
狼尾草/蛇尾草无融合生殖相关基因组区域的分子特征
DOI：
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发表时间：
2003
影响因子：
2.9
通讯作者：
W. Hanna
中科院分区：
文献类型：
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作者：
P. Ozias‐Akins;Y. Akiyama;W. Hanna
无融合生殖被定义为通过种子进行无性繁殖，尽管这一结果可以通过多种途径实现。由于对这些通路的分子控制知之甚少，它们可能如何相交也是一个谜。在禾本科植物中，有两条这样的途径，即复孢子和无孢子，正受到分子生物学家的关注。狼尾草和虎尾草属植物的无孢子形成四核胚囊，缺乏反足。有性生殖经常流产，因此产生的种子由(1)在遗传上与母亲相同的孤雌生殖胚胎和(2)通过假受精形成的胚乳组成。无融合生殖的传递与单个染色体上的连锁区块的转移有关。该连锁区块包含重复序列以及半合子、低拷贝的DNA序列。荧光原位杂交表明，在所研究的多倍体无融合生殖体内，这些DNA区域只出现在一条染色体上，而不是它的同源物上。无融合生殖相关区域的特征类似于从重组中分离出来的其他染色体片段，并充满了“自私”的DNA。
Apomixis is defined as asexual reproduction through seeds, although this outcome can be achieved by multiple pathways. Since little is known about the molecular control of these pathways, how they might intersect is also a mystery. Two of these pathways in the grass family, diplospory and apospory, are receiving attention from molecular biologists. Apospory in Pennisetum/Cenchrus, two genera of panicoid grasses, results in the formation of four-nucleate embryo sacs that lack antipodals. Sexual reproduction frequently aborts so that the resulting seed is composed of (1) a parthenogenetically derived embryo that is genetically identical to the mother and (2) endosperm formed through pseudogamy. The transmission of apomixis is associated with the transfer of a linkage block on a single chromosome. This linkage block contains repetitive sequences as well as hemizygous, low-copy DNA sequences. Fluorescence in situ hybridization has demonstrated that these DNA regions occur on only a single chromosome, but not its homologs, in the polyploid apomicts studied. Features of the apomixis-associated region resemble those of other chromosomal segments isolated from recombination and replete with "selfish" DNAs.