小背景：Chromosomal rearrangements and gene copy number variation (CNV) are two important tools for genome evolution and sources for the creation of new genes.

问题：However, their emergence takes many generations.

主要发现：In this study, we show that in Arabidopsis thaliana, a significant loss of ribosomal RNA (rRNA) genes with a past history of a mutation for the chromatin assembly factor 1 (CAF1) complex causes rapid changes in the genome structure.

结果1-大片段同向串联重复：Using long-read sequencing and microscopic approaches, we have identified up to 15 independent large tandem duplications in direct orientation (TDDOs) ranging from 60 kb to 1.44 Mb. Our data suggest that these TDDOs appeared within a few generations, leading to the duplication of hundreds of genes.

结果2-TDDOs的影响：By subsequently focusing on a line only containing 20% of rRNA gene copies (20rDNA line), we investigated the impact of TDDOson 3D genome organization, gene expression, and cytosine methylation. We found that duplicated genes often accumulate more transcripts. Among them, several are involved in plant–pathogen response, which could explain why the 20rDNA line is hyper-resistant to both bacterial and nematode infections. Finally, we show that the TDDOs create gene fusions and/or truncations and discuss their potential implications for the evolution of plant genomes.