McCarthy Elizabeth W, Berardi Andrea E, Smith Stacey D, Litt Amy
Department of Botany and Plant Sciences, University of California, Riverside, 2109 Batchelor Hall, Riverside, California 92521 USA.
University of Colorado, Boulder, C127 Ramaley Hall, Campus Box 334, Boulder, Colorado 80309 USA.
Am J Bot. 2017 Jan;104(1):92-101. doi: 10.3732/ajb.1600350. Epub 2017 Jan 5.
Both polyploidy and shifts in floral color have marked angiosperm evolution. Here, we investigate the biochemical basis of the novel and diverse floral phenotypes seen in allopolyploids in Nicotiana (Solanaceae) and examine the extent to which the merging of distinct genomes alters flavonoid pigment production.
We analyzed flavonol and anthocyanin pigments from Nicotiana allopolyploids of different ages (N. tabacum, 0.2 million years old; several species from Nicotiana section Repandae, 4.5 million years old; and five lines of first-generation synthetic N. tabacum) as well as their diploid progenitors.
Allopolyploid floral pigment profiles tend not to overlap with their progenitors or related allopolyploids, and allopolyploids produce transgressive pigments that are not present in either progenitor. Differences in floral color among N. tabacum accessions seems mainly to be due to variation in cyanidin concentration, but changes in flavonol concentrations among accessions are also present.
Competition for substrates within the flavonoid biosynthetic pathway to make either flavonols or anthocyanins may drive the differences seen among related allopolyploids. Some of the pigment differences observed in allopolyploids may be associated with making flowers more visible to nocturnal pollinators.
多倍体和花色变化在被子植物进化过程中都具有显著意义。在此，我们研究了烟草属（茄科）异源多倍体中出现的新奇多样的花表型的生化基础，并探讨了不同基因组融合在多大程度上改变了类黄酮色素的产生。
我们分析了不同年代的烟草属异源多倍体（烟草，20万年；烟草属Repandae组的几个物种，450万年；以及五代第一代人工合成烟草）及其二倍体祖先的黄酮醇和花青素色素。
异源多倍体的花色素谱往往与其祖先或相关异源多倍体不重叠，并且异源多倍体产生了其两个祖先中都不存在的超亲色素。烟草不同种间花色的差异似乎主要是由于花青素浓度的变化，但种间黄酮醇浓度也存在变化。
在类黄酮生物合成途径中，用于合成黄酮醇或花青素的底物竞争可能导致相关异源多倍体之间出现差异。在异源多倍体中观察到的一些色素差异可能与使花朵对夜间传粉者更具可见性有关。
