Recovery of a sexual and an apomictic hybrid from crosses between the facultative apomicts Hieracium caespitosum and H. praealtum
Recovery of a sexual and an apomictic hybrid from crosses between the facultative apomicts Hieracium caespitosum and H. praealtum
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从兼性无性生殖 Hieracium caespitosum 和 H. praealtum 之间的杂交中恢复有性和无性生殖杂种
DOI：
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
R. Bicknell
中科院分区：
文献类型：
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作者：
H. Chapman;R. Bicknell
在系性无融合生殖的物种中，杂交是一种罕见的现象。我们报道了两个杂种的恢复从互惠杂交的无融合生殖物种的Hieracium praealtum和H。丛生的双亲均为四倍体（2n=4x=36）。H. cespitosum x H. praealtum（CR6）为六倍体（2n=6x=54），无融合生殖。倍性数目的增加是BIII杂种起源的证据，其起源于减数配子和未减数配子的融合。相反，杂种从正反交H恢复。praealtum x H. caespitosum（RC 4）是一个四倍体，因此可能是由两个减数配子融合而成的BII杂种。进一步的证据是这种植物的性表达。由于山柳菊属的无融合生殖被认为是由一个单一的显性基因座决定的，有性植株符合一种遗传模型，其中这代表了假定的纯合隐性表型。无融合生殖体杂交形成有性植物具有潜在的重要进化意义。种间BIII杂种的形成以前没有记录。
Hybridisation is a rare event in facultatively apomictic species. We report the recovery of two hybrids from reciprocal crosses between the facultatively apomictic species Hieracium praealtum and H. caespitosum. Both parents were tetraploid (2n=4x=36). H. caespitosum x H. praealtum (CR6) was a hexaploid (2n=6x=54) and an apomict. The increased ploidy number is evidence of a BIII hybrid origin, having arisen from the fusion of a reduced and an unreduced gamete. In contrast, the hybrid recovered from the reciprocal cross H. praealtum x H. caespitosum (RC4) was a tetraploid and therefore probably arose as a BII hybrid from the fusion of two reduced gametes. Further evidence for this is the expression of sexuality in this plant. As apomixis in Hieracium is thought to be determined by a single dominant locus, a sexual plant is consistent with a model of inheritance where this represents the putative homozygous recessive phenotype. The formation of a sexual plant from the hybridisation of apomicts has potentially significant evolutionary implications. The formation of an interspecific BIII hybrid has not previously been recorded.