Post-pollination hybridization barriers in Nicotiana section Alatae
Post-pollination hybridization barriers in Nicotiana section Alatae
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DOI：
10.1007/s00497-008-0077-9
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发表时间：
2008-09-01
影响因子：
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通讯作者：
Holtsford, Timothy P.
中科院分区：
文献类型：
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作者：
Lee, Christopher B.;Page, Lawrence E.;Holtsford, Timothy P.
Nicotiana Section Alcohol包含8种不同的花大小和形态。组成员很容易杂交在温室中，但没有杂交种已观察到在自然同域和parapatric人口。为了研究种间杂交关系的机制，防止杂交，所有成员的部分Alcohol在一个完整的杂交。在同种杂交中，花粉供体雌蕊长度与种间结实率呈正相关。花粉管生长速率与花粉供体雌蕊长度呈显著正相关。此外，短雌蕊成员的部分Alberta的花粉只能增长的最大距离成正比，但大于，自己的雌蕊长度。我们的研究结果表明，花粉管生长能力（即，速率和距离），在长雌蕊物种x短雌蕊物种杂交中提供了杂交障碍。我们还发现了另一个杂交障碍，而不是具体相关的花粉管生长能力在短雌蕊物种×沿雌蕊物种。两者合计，这些障碍通常可以描述为一个“雌蕊长度不匹配”的规则，在部分Alcohol，花粉具有最成功的胚珠与雌蕊长度相似的物种自己。这一规则可能有助于杂交障碍，因为该物种显示显着不同的雌蕊长度在组Alcohol。
Nicotiana section Alatae contains eight species with variable flower sizes and morphologies. Section members readily hybridize in the glasshouse, but no hybrids have been observed in natural sympatric and parapatric populations. To investigate interspecific crossing relationships with respect to mechanisms preventing hybridization, all members of section Alatae were intercrossed in a complete diallel. We found positive correlation between the pistil length of the pollen donor and interspecific seed set relative to the conspecific cross. Pollen tube growth rate and pollen donor pistil length were positively correlated as well. Furthermore, pollen from short-pistil members of section Alatae could only grow a maximum distance proportional to, but greater than, their own pistil lengths. Our results show that pollen tube growth capacity (i.e., rate and distance), provides a hybridization barrier in long-pistil species x short-pistil species crosses. We also found another hybridization barrier not specifically related to pollen tube growth capacity in short-pistil species x along-pistil species. Taken together, these barriers can generally be described by a 'pistil-length mismatch' rule; in section Alatae, pollen has the most success fertilizing ovules from species with pistil lengths similar to their own. This rule could contribute to hybridization barriers in Section Alatae because the species display dramatically different pistil lengths.