Polyploidy or whole genome duplication (WGD) is an evolutionary phenomenon that happened in all angiosperms multiple times over millions of years. Extensive studies on the model plant Arabidopsis thaliana genome have revealed that it has undergone five rounds of WGDs followed, in the Brassicaceae tribe, by a characteristic whole genome triplication (WGT). In addition, small-scale events such as tandem or segmental duplications and retrotransposition also enable plants to reshape their genomes. Over the decades, extensive research efforts have been undertaken to understand the evolutionary significance of polyploidy. On the other hand, much less attention has been paid to understanding the impact of gene duplication on the diversification of important stress response genes. The main objective of this review is to discuss key aspects of gene and genome duplications with a focus on genes primarily regulated by osmotic stresses. The focal family is the Brassicaceae, since it (i) underwent multiple rounds of WGDs plus WGTs, (ii) hosts many economically important crops and wild relatives that are tolerant to a range of stresses, and (iii) comprises many species that have already been sequenced. Diverse molecular mechanisms that lead to structural and regulatory alterations of duplicated genes are discussed. Examples are drawn from recent literature to elucidate expanded, stress responsive gene families identified from different Brassica crops. A combined bioinformatic and transcriptomic method has been proposed and tested on a known stress-responsive gene pair to prove that stress-responsive duplicated allelic variants can be identified by this method. Finally, future prospects for engineering these genes into crops to enhance stress tolerance are discussed, and important resources for Brassica genome research are provided.

中文翻译：

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芸苔属植物中的基因重复和胁迫基因组学：目前的理解和未来前景

多倍体或全基因组重复 (WGD) 是一种进化现象，在所有被子植物中发生了数百万年多次。对模式植物拟南芥基因组的广泛研究表明，它经历了五轮 WGD，随后在十字花科部落中进行了特征性的全基因组三倍体 (WGT)。此外，串联或节段复制和逆转录转座等小规模事件也使植物能够重塑其基因组。几十年来，已经进行了广泛的研究工作以了解多倍体的进化意义。另一方面，对了解基因重复对重要应激反应基因多样化的影响的关注要少得多。本综述的主要目的是讨论基因和基因组重复的关键方面，重点是主要受渗透胁迫调节的基因。焦点科是十字花科，因为它 (i) 经历了多轮 WGDs 和 WGTs，(ii) 拥有许多经济上重要的作物和能够耐受一系列压力的野生近缘种，以及 (iii) 包括许多已经被排序。讨论了导致重复基因结构和调控改变的多种分子机制。从最近的文献中抽取了一些例子来阐明从不同芸苔属作物中鉴定的扩展的、胁迫响应基因家族。已经提出了一种组合的生物信息学和转录组学方法，并在已知的应激反应基因对上进行了测试，以证明可以通过这种方法识别应激反应性重复等位基因变体。最后，讨论了将这些基因工程化到作物中以增强抗逆性的未来前景，并为芸苔属基因组研究提供了重要资源。