School of Biotechnology, Gautam Buddha University, Greater Noida, 201310, India.
Planta. 2021 Aug 30;254(3):62. doi: 10.1007/s00425-021-03711-3.
Majority of differentially expressed miRNAs with functional attributes have been recruited independently and parallelly during allopolyploidy followed by the millennia of human selection of both domesticated G. hirsutum and G. barbadense. The genus Gossypium is a marvelous evolutionary model for studying allopolyploidy and morpho-evolution of long-spinnable fibers from the ancestral wild-fuzz. Many genes, transcription factors, and notably, the regulatory miRNAs essentially govern such remarkable modern fiber phenotypes. To comprehend the impact of allopolyploidy on the evolutionary selection of transcriptional dynamicity of key miRNAs, comparative transcriptome profiling of vegetative and fiber tissues of domesticated diploid G. arboreum (A) and allopolyploid cotton species G. hirsutum (AD), and G. barbadense (AD) identified > 300 differentially expressed miRNAs (DEmiRs) within or between corresponding tissues of A, AD and AD species. Up to 49% and 32% DEmiRs were up- and down-regulated at fiber initiation stage of AD and AD species, respectively, whereas 50% and 18% DEmiRs were up- and down-regulated at fiber elongation stage of both the allopolyploid species. Interestingly, A-subgenome-specific DEmiRs exhibit expression dominance in the allopolyploid genetic backgrounds. Comparative spatio-temporal expression analyses of AD and AD species discovered that a majority of DEmiRs were recruited independently under millennia of human selection during domestication. Functional annotations of these DEmiRs revealed selection of associated molecular functions such as hormone-signaling, calcium-signaling and reactive oxygen species (ROS) signaling during fiber initiation and elongation. To validate the functional attributes of annotated DEmiRs, we demonstrated for the first time that the target-mimicry-based constitutive diminution of auxin-signaling associated miR167 directly affected the differentiation of floral and fiber tissues of transgenic cotton. These results strongly suggested that the evolutionarily favored DEmiRs including miR167 were involved in the transcriptional regulation of numerous genes during cotton evolution for enhanced fiber-associated agronomic traits.
大多数具有功能属性的差异表达 miRNA 已在异源多倍体形成后独立平行地被招募，并在随后的数千年中经历了人类对驯化的 G. hirsutum 和 G. barbadense 的选择。棉属是研究异源多倍体和从祖先野生棉到长纤维的形态进化的极好的进化模型。许多基因、转录因子，特别是调控 miRNA，对这些显著的现代纤维表型起着关键作用。为了理解异源多倍体对关键 miRNA 转录动态进化选择的影响，对二倍体野生棉 G. arboreum (A) 和异源多倍体棉花种 G. hirsutum (AD)和 G. barbadense (AD)的营养组织和纤维组织进行了比较转录组分析，鉴定了 A、AD 和 AD 种相应组织中超过 300 个差异表达 miRNA (DEmiR)。在 AD 和 AD 种纤维起始阶段，分别有高达 49%和 32%的 DEmiR 上调和下调，而在两个异源多倍体种的纤维伸长阶段，分别有 50%和 18%的 DEmiR 上调和下调。有趣的是，A 亚基因组特异性 DEmiR 在异源多倍体遗传背景中表现出表达优势。AD 和 AD 种的比较时空表达分析发现，在驯化过程中，经过数千年的人类选择，大多数 DEmiR 是独立招募的。对这些 DEmiR 的功能注释表明，在纤维起始和伸长过程中，与激素信号、钙信号和活性氧 (ROS) 信号相关的分子功能发生了选择。为了验证注释的 DEmiR 的功能属性，我们首次证明了基于靶模拟的生长素信号相关 miR167 的组成性减少直接影响了转基因棉花的花和纤维组织的分化。这些结果强烈表明，包括 miR167 在内的进化上有利的 DEmiR 参与了棉花进化过程中众多基因的转录调控，以增强与纤维相关的农艺性状。
