Whole genome duplication (WGD) provides new genetic material for genome evolution. After a WGD event, some duplicates are lost, while other duplicates still persist and evolve diverse functions. A particular challenge is to understand how this diversity arises. This study identified two WGD-derived duplicates, MYB158 and MYB189, from Populus tomentosa. Populus MYB158 and MYB189 had expression divergence. Populus tomentosa overexpressing MYB158 or MYB189 had similar phenotypes: creep growth, decreased width of xylem and secondary cell wall thickness. Compared to wild-type, neither myb158 mutant nor myb158 myb189 double mutant showed obvious phenotypic variation in P. tomentosa. Although MYB158 and MYB189 proteins could repress the same structural genes involved in lignin, cellulose, and xylan biosynthesis, the two proteins had their own specific regulatory targets. Populus MYB158 could act as the upstream regulator of secondary cell wall NAC master switch and directly represses the expression of the SND1-B2 gene. Taken together, Populus MYB158 and MYB189 have retained similar functions in negatively regulating secondary cell wall biosynthesis, but have evolved partially distinct functions in direct regulation of NAC master switch, with MYB158 playing a more crucial role. Our findings provide new insights into the evolutionary and functional divergence of WGD-derived duplicate genes.

中文翻译：

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全基因组复制产生的杨树MYB158和MYB189基因对的功能差异

全基因组复制 (WGD) 为基因组进化提供了新的遗传物质。在 WGD 事件之后，一些重复项丢失了，而其他重复项仍然存在并演变出不同的功能。一个特殊的挑战是了解这种多样性是如何产生的。本研究确定了来自毛白杨的两个 WGD 衍生的重复序列 MYB158和MYB189。杨属MYB158和MYB189有表达差异。过表达MYB158或MYB189的毛白杨具有相似的表型：蠕变生长、木质部宽度减小和次生细胞壁厚度。与野生型相比，myb158突变体和myb158 myb189双突变体在毛白杨中表现出明显的表型变异。尽管 MYB158 和 MYB189 蛋白可以抑制参与木质素、纤维素和木聚糖生物合成的相同结构基因，但这两种蛋白有自己特定的调控目标。杨树MYB158可作为次生细胞壁NAC总开关的上游调节因子，直接抑制SND1-B2基因的表达。综上所述，杨树 MYB158和MYB189在负调节次生细胞壁生物合成方面保留了相似的功能，但在直接调节 NAC 总开关方面具有部分不同的功能，与MYB158发挥更关键的作用。我们的研究结果为 WGD 衍生的重复基因的进化和功能差异提供了新的见解。