Yang Zhenzhen, Wafula Eric K, Honaas Loren A, Zhang Huiting, Das Malay, Fernandez-Aparicio Monica, Huang Kan, Bandaranayake Pradeepa C G, Wu Biao, Der Joshua P, Clarke Christopher R, Ralph Paula E, Landherr Lena, Altman Naomi S, Timko Michael P, Yoder John I, Westwood James H, dePamphilis Claude W
Intercollege Graduate Program in Plant Biology, Huck Institutes of the Life Sciences, The Pennsylvania State University Department of Biology, The Pennsylvania State University Institute of Molecular Evolutionary Genetics, Huck Institutes of the Life Sciences, The Pennsylvania State University.
Department of Biology, The Pennsylvania State University Institute of Molecular Evolutionary Genetics, Huck Institutes of the Life Sciences, The Pennsylvania State University.
Mol Biol Evol. 2015 Mar;32(3):767-90. doi: 10.1093/molbev/msu343. Epub 2014 Dec 21.
The origin of novel traits is recognized as an important process underlying many major evolutionary radiations. We studied the genetic basis for the evolution of haustoria, the novel feeding organs of parasitic flowering plants, using comparative transcriptome sequencing in three species of Orobanchaceae. Around 180 genes are upregulated during haustorial development following host attachment in at least two species, and these are enriched in proteases, cell wall modifying enzymes, and extracellular secretion proteins. Additionally, about 100 shared genes are upregulated in response to haustorium inducing factors prior to host attachment. Collectively, we refer to these newly identified genes as putative "parasitism genes." Most of these parasitism genes are derived from gene duplications in a common ancestor of Orobanchaceae and Mimulus guttatus, a related nonparasitic plant. Additionally, the signature of relaxed purifying selection and/or adaptive evolution at specific sites was detected in many haustorial genes, and may play an important role in parasite evolution. Comparative analysis of gene expression patterns in parasitic and nonparasitic angiosperms suggests that parasitism genes are derived primarily from root and floral tissues, but with some genes co-opted from other tissues. Gene duplication, often taking place in a nonparasitic ancestor of Orobanchaceae, followed by regulatory neofunctionalization, was an important process in the origin of parasitic haustoria.
新性状的起源被认为是许多主要进化辐射背后的一个重要过程。我们利用三种列当科植物的比较转录组测序，研究了寄生开花植物的新型取食器官吸器进化的遗传基础。在宿主附着后，至少有两个物种的吸器发育过程中约有180个基因上调，这些基因在蛋白酶、细胞壁修饰酶和细胞外分泌蛋白中富集。此外，在宿主附着之前，约有100个共享基因对吸器诱导因子有上调反应。我们将这些新发现的基因统称为假定的“寄生基因”。这些寄生基因大多来源于列当科植物和相关非寄生植物黄花沟酸浆共同祖先中的基因复制。此外，在许多吸器基因中检测到了特定位点上放松的纯化选择和/或适应性进化的特征，这可能在寄生虫进化中起重要作用。对寄生和非寄生被子植物基因表达模式的比较分析表明，寄生基因主要来源于根和花组织，但也有一些基因是从其他组织中借用的。基因复制通常发生在列当科植物的非寄生祖先中，随后通过调控新功能化，这是寄生吸器起源的一个重要过程。
