Bai Yanbo, Zhao Kanglu, Wang Bo, Wu Lei, Xiong Zhiyong
Key Laboratory of Herbage and Endemic Crop Biology, Ministry of Education, School of Life Sciences, Inner Mongolia University, Hohhot, 010070, China.
State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou, 311300, China.
BMC Plant Biol. 2025 Feb 19;25(1):226. doi: 10.1186/s12870-025-06236-z.
The genomes of allopolyploids newly formed through hybridization and polyploidization exhibit substantial changes including those at genetic and epigenetic levels. These alterations may affect their gene expression patterns, leading to nonadditive gene expression. Currently, only a few reports are available on the impact of nonadditive gene expressions on traits.
Using six isogenic resynthesized Brassica napus lines across the first 10 generations, we studied the impact of gene expression patterns on flowering time. The expression levels of a group of genes, located on chromosome A09, were significantly positively correlated with flowering time. According to the expression analysis, the expression levels of the homologous pairs of 139 genes on chromosome A09 were lower in allopolyploids than in their diploid parents, which indicated a phenomenon of transgressive expression. Additionally, independent subgenomic analysis of homoeologous gene pairs on chromosome A09 of the allopolyploids demonstrated that the gene expression levels of B. napus subgenome A (BnA) and subgenome C (BnC) were similar. However, in two aneuploids carrying monosomic or trisomic A09 chromosome, the gene expression levels of BnA were lower or higher than those of BnC, and the corresponding flowering times of these two aneuploids were earlier and later, respectively.
These findings indicate that changes in gene dosage introduce biases in the expression of homoeologous genes. Moreover, upregulation or downregulation of homoeologous gene expression on a single chromosome partially alters the flowering time of the newly formed allopolyploid B. napus, which is of great significance for horticultural applications and future research on genetic mechanisms.
通过杂交和多倍体化新形成的异源多倍体的基因组表现出大量变化，包括遗传和表观遗传水平的变化。这些改变可能影响其基因表达模式，导致非加性基因表达。目前，关于非加性基因表达对性状影响的报道较少。
利用六个在前10代重新合成的甘蓝型油菜同基因系，我们研究了基因表达模式对开花时间的影响。位于A09染色体上的一组基因的表达水平与开花时间显著正相关。根据表达分析，A09染色体上139个基因的同源对在异源多倍体中的表达水平低于其二倍体亲本，这表明存在超亲表达现象。此外，对异源多倍体A09染色体上同源基因对的独立亚基因组分析表明，甘蓝型油菜A亚基因组（BnA）和C亚基因组（BnC）的基因表达水平相似。然而，在两个携带A09染色体单体或三体的非整倍体中，BnA的基因表达水平低于或高于BnC，这两个非整倍体的相应开花时间分别较早和较晚。
这些发现表明基因剂量的变化会导致同源基因表达出现偏差。此外，单条染色体上同源基因表达的上调或下调部分改变了新形成的异源多倍体甘蓝型油菜的开花时间，这对园艺应用和未来遗传机制研究具有重要意义。
