Interspecific hybrid ancestry of a plant adaptive radiation: Allopolyploidy of the Hawaiian silversword alliance (Asteraceae) inferred from floral homeotic gene duplications
Interspecific hybrid ancestry of a plant adaptive radiation: Allopolyploidy of the Hawaiian silversword alliance (Asteraceae) inferred from floral homeotic gene duplications
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DOI：
10.1093/oxfordjournals.molbev.a026200
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发表时间：
1999-08-01
影响因子：
10.7
通讯作者：
Purugganan, MD
中科院分区：
文献类型：
--
作者：
Barrier, M;Baldwin, BG;Purugganan, MD
多倍体夏威夷银剑联盟（菊科）是植物中适应性辐射的一个引人注目的例子，之前已被证明是北美马迪亚/Raillardiopsis组的塔草的后代。主要是二倍体组合。银剑联盟中多倍体条件的起源在早期的生物系统、细胞遗传学和分子研究中并未得到解决，除了确定现代马迪亚/Raillardiopsis物种的多倍体独立于夏威夷群体的多倍体之外。我们确定，在夏威夷银剑联盟成员体内发现了两个花同源异型基因 ASAP3/TM6 和 ASAP1，它们似乎是由于两个北美塔草物种之间的种间杂交而产生的。我们对 4SAP3/TM6 位点的分子系统发育分析表明，夏威夷银剑联盟祖先中的种间杂交事件涉及包括 Raillardiopsis muirii（也许还有 Madia nutans）和 Raillardiopsis scabrida 在内的谱系成员。 ASAP1 分析还表明，这两种 Raillardiopsis 是夏威夷银剑联盟最接近的北美亲戚之一。先前的生物系统证据表明，两个北美油草谱系的成员之间有可能形成异源多倍体。 ii 之间的有力杂种。 muirii 和 R.scabrida 已经产生，形成有活力的、大部分是四孔（二倍体）花粉，与观察到的减数分裂失败一致。异源多倍体的各种遗传后果可能有助于解释银剑联盟惊人的进化多样化。
The polyploid Hawaiian silversword alliance (Asteraceae), a spectacular example of adaptive radiation in plants, was shown previously to have descended from North American tarweeds of the Madia/Raillardiopsis group; a primarily diploid assemblage. The origin of the polyploid condition in the silversword alliance was not resolved in earlier biosystematic, cytogenetic, and molecular studies, apart from the determination that polyploidy in modern species of Madia/Raillardiopsis arose independent of that of the Hawaiian group. We determined that two floral homeotic genes, ASAP3/TM6 and ASAP1, are found in duplicate copies within members of the Hawaiian silversword alliance and appear to have arisen as a result Of interspecific hybridization between two North American tarweed species. Our molecular phylogenetic analyses of the 4SAP3/TM6 loci suggest that the interspecific hybridization event in the ancestry of the Hawaiian silversword alliance involved members of lineages that include Raillardiopsis muirii (and perhaps Madia nutans) and Raillardiopsis scabrida. The ASAP1 analysis also indicates that the two species of Raillardiopsis are among the closest North American relatives of the Hawaiian silversword alliance. Previous biosystematic evidence demonstrates the potential for allopolyploid formation between members of the two North American tarweed lineages; a vigorous hybrid between ii. muirii and R. scabrida has been produced that formed viable, mostly tetraporate (diploid) pollen, in keeping with observed meiotic failure. Various genetic consequences of allopolyploidy may help to explain the phenomenal evolutionary diversification of the silversword alliance.