Characterization of Two AGL6-Like Genes from a Chinese Endemic Woody Tree, Manglietia patungensis (Magnoliaceae) Provides Insight into Perianth Development and Evolution in Basal Angiosperms
Characterization of Two AGL6-Like Genes from a Chinese Endemic Woody Tree, Manglietia patungensis (Magnoliaceae) Provides Insight into Perianth Development and Evolution in Basal Angiosperms
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中国特有木本木莲（木兰科）的两个 AGL6 样基因的表征为基部被子植物的花被发育和进化提供了见解
DOI：
10.3390/f10080669
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发表时间：
2019-08-01
期刊：
影响因子：
2.9
通讯作者：
Chen, Faju
中科院分区：
文献类型：
--
作者：
Liu, Zhixiong;Zhang, Kebin;Chen, Faju
巴东木莲（Magnolietia patungensis，木兰科）花朵呈放射状对称，其花被由第一轮的三个独立的萼片状花被片和内部的两个轮层的六个花瓣状花被片组成，这与大多数木兰科物种的花朵具有明显的差异，其包含三个均匀的花瓣状花被片轮，使其成为了解早期花演化过程中花被形态分化的良好模型。在此，从 M. patungensis 中分离出两个 AGL6 直系同源物 MapaAGL6-1 和 MapaAGL6-2。序列比对和系统发育分析将这两个基因归入 AGL6 谱系。 MapaAGL6-1仅在花被轮中表达，而MapaAGL6-2在花被轮中强表达，但在雌蕊中低表达。此外，MapaAGL6-1的异位表达在拟南芥ap1-10花中导致强烈的互补表型，并且在4个花轮中产生正常花器官，仅在第2轮中花瓣数量减少，而MapaAGL6-2的异位表达仅导致拟南芥ap1-10突变体中花瓣部分被拯救，但未能终止心盘体发育。此外，由显示强表型的35S::MapaAGL6-1转基因植物和显示表型变化的35S::MapaAGL6-2转基因植物杂交产生的子系产生正常的花。我们的结果表明，MapaAGL6-1是木兰科植物中控制花被特性的合理A功能基因，这从其在拟南芥ap1突变体中的表达区域和互补表型推断出来，而MapaAGL6-2主要参与花瓣状花被片的发育。我们的数据还为揭示基部被子植物的花被发育和早期进化提供了新线索。
Manglietia patungensis (Magnoliaceae) exhibits radially symmetric flowers with perianth consisting of three separate sepaloid tepals in whorl 1 and six petaloid tepals in the inner two whorls, which shows an obvious difference from flowers of most Magnoliaceae species that contain three uniform petaloid tepals whorls, and make it an excellent model for understanding perianth morphology differentiation during early flower evolution. Here, two AGL6 orthologs, MapaAGL6-1 and MapaAGL6-2, were isolated from M. patungensis. Sequence alignment and phylogenetic analyses grouped both genes into the AGL6 lineage. MapaAGL6-1 is expressed only in the perianth whorls, while MapaAGL6-2 is strongly expressed in the perianth whorls but is lowly expressed in gynoecium. Furthermore, ectopic expression of MapaAGL6-1 results in strong complementation phenotypes in the Arabidopsis ap1-10 flower and production of normal floral organs in four floral whorls only with the petal number reduced in whorl 2, while ectopic expression of MapaAGL6-2 only results in petals partly rescued but failing to terminate carpelloid development in Arabidopsis ap1-10 mutant. In addition, the daughter lines generated from a cross between 35S::MapaAGL6-1 transgenic plants showing strong phenotypes and 35S::MapaAGL6-2 transgenic plants showing phenotypic changes produce normal flowers. Our results suggest that MapaAGL6-1 is a reasonable A-function gene controlling perianth identity in Magnoliaceae, which infers from its expression region and complementation phenotypes in Arabidopsis ap1 mutant, while MapaAGL6-2 is mainly involved in petaloid tepal development. Our data also provide a new clue to uncover the perianth development and early evolution in basal angiosperms.