Department of Biology, University of Florida, Gainesville, FL 32611, USA.
New Phytol. 2010 Apr;186(1):175-83. doi: 10.1111/j.1469-8137.2010.03205.x.
Recent years have seen rapid advances in our knowledge of the transcriptomic consequences of allopolyploidy, primarily through the study of polyploid crops and model systems. However, few studies have distinguished between homoeologs and between tissues, and still fewer have examined young natural allopolyploid populations of independent origin, whose parental species are still present in the same location. Here, we examined the expression of 13 homoeolog pairs in seven tissues of 10 plants of allotetraploid Tragopogon mirus from two natural populations formed by independent polyploidizations between Tragopogon dubius and Tragopogon porrifolius c. 40 generations ago. We compare these with patterns of expression in the diploid parental species from the same locality. Of the 910 assays in T. mirus, 576 (63%) showed expression of both homoeologs, 63 (7%) showed no expression of either homoeolog, 186 (20%) showed nonexpression of one homoeolog across all tissues of a plant, and 72 (8%) showed non-expression of a homoeolog in a particular tissue within a plant. We found two cases of reciprocal tissue-specific expression between homoeologs, potentially indicative of subfunctionalization. Our study shows that tissue-specific silencing, and even apparent subfunctionalization, can arise rapidly in the early generations of natural allopolyploidy.
近年来，我们对异源多倍体转录组后果的认识取得了快速进展，这主要得益于多倍体作物和模式系统的研究。然而，很少有研究能够区分同源基因对和组织，更少研究考察具有独立起源的年轻自然异源多倍体群体，这些群体的双亲种仍存在于同一地点。在这里，我们研究了 10 株来自两个自然种群的异源四倍体 Tragopogon mirus 的 7 种组织中的 13 对同源基因对的表达情况，这两个种群是大约 40 代前 Tragopogon dubius 和 Tragopogon porrifolius 之间的独立多倍化形成的。我们将这些与来自同一地点的二倍体亲种的表达模式进行了比较。在 T. mirus 的 910 个检测中，有 576 个（63%）同时表达了两个同源基因对，有 63 个（7%）没有表达任何一个同源基因对，186 个（20%）在一个植物的所有组织中都没有表达一个同源基因对，有 72 个（8%）在一个植物的特定组织中没有表达一个同源基因对。我们发现了两个同源基因对之间组织特异性表达的情况，这可能表明了功能的次优化。我们的研究表明，组织特异性沉默，甚至明显的次功能化，都可以在自然异源多倍体的早期世代迅速产生。
