Apomixis via recombination of genome regions for apomeiosis (diplospory) and parthenogenesis in Erigeron (daisy fleabane, Asteraceae)
Apomixis via recombination of genome regions for apomeiosis (diplospory) and parthenogenesis in Erigeron (daisy fleabane, Asteraceae)
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DOI：
10.1007/s00497-005-0017-x
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发表时间：
2006-02
影响因子：
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通讯作者：
R. Noyes
中科院分区：
文献类型：
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作者：
R. Noyes
摘要雏菊（ErigeronannuusandE.strigosus）的无融合生殖受两个遗传上不连锁的基因座控制，这两个基因座独立地调节未减数雌配子体的形成（无融合生殖、倍数孢子体形成）和自主种子的形成（孤雌生殖）。在这项工作中，完全无融合生殖的F2再生杂交F1轴承，分别，这两个功能区。两个三倍体（3x= 2n = 27）高度二倍体孢子F1作为种子亲本的非整倍体（2x+ 1 = 2n = 19）减数分裂花粉供体轴承4 AFLP标记连锁孤雌生殖种子形成，但只产生败育胚和胚乳。在408个杂种中，有21个（5.1%）产生了种子。这些假定的无融合生殖体中有9个是四倍体（4x），可能结合了来自二倍体孢子种子亲本的未减数卵和来自花粉亲本的单倍体配子（3x+x）。其他12个杂种无融合生殖体为五倍体，解释为产生于未减数的二倍体孢子卵与未减数的精子细胞的融合（3x+ 2x）。分析表明，21个合成的无融合生殖体中除了3个外，其余都重组了与倍数孢子体形成和孤雌生殖相关的标记。此外，三个额外的杂交组合标记链接到两个功能区域，但只产生流产胚胎。无融合生殖体的二倍体孢子胚珠比例（4.7-95.3%）和发育成种子的胚珠比例（3.8-58.0%）各不相同。这些结果支持了这样的假设，即无融合生殖和自主种子形成在遗传上是不同的，并且这些性状可以被分离和重组以产生在接近野生型水平下表现出无融合生殖的杂种。
Apomixis in daisy fleabanes (ErigeronannuusandE.strigosus) is controlled by two genetically unlinked loci that regulate, independently, the formation of unreduced female gametophytes (apomeiosis, diplospory) and autonomous seed formation (parthenogenesis). In this work, fully apomictic F2s were regenerated by crossing F1s bearing, separately, these two functional regions. Two triploid (3x= 2n = 27) highly diplosporous F1s served as seed parents to an aneuploid (2x+ 1 = 2n = 19) meiotic pollen donor bearing four AFLP markers linked to parthenogenetic seed formation but producing only abortive embryos and endosperm. Of 408 hybrids, 21 (5.1%) produced seed. Nine of these putative apomicts were tetraploids (4x), likely combining an unreduced egg from the diplosporous seed parent and a haploid gamete from the pollen parent (3x+x). The other 12 hybrid apomicts were pentaploid, interpreted as arising from the fusion of an unreduced diplosporous egg with an unreduced sperm cell (3x+ 2x). Analysis indicated that all but three of the 21 synthetic apomicts recombined markers linked to diplospory and parthenogenesis. In addition, three additional hybrids combined markers linked to the two functional regions but produced only aborted embryos. The apomicts varied in percentage of diplosporous ovules (4.7–95.3% of all ovules produced) and in percentage of ovules that developed into seed (3.8–58.0%). These results support the hypothesis that apomeiosis and autonomous seed formation are genetically distinct, and that the traits can be separated and recombined to create hybrids exhibiting apomixis at near wildtype levels.