Effect of aneuploidy of a non‐essential chromosome on gene expression in maize. (1st March 2022)

• Record Type: Journal Article
• Authors: Shi, Xiaowen; Yang, Hua; Chen, Chen; Hou, Jie; Ji, Tieming; Cheng, Jianlin; Birchler, James A.
• Is Part Of: Plant journal. Volume 110:Number 1(2022)
• Page Start: 193
• Page End: 211
• Publication Date: 2022-03-01
• Subjects: B chromosome -- gene expression -- maize -- dosage‐sensitive modulation -- microRNA; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.15665
• Languages: English
• ISSNs: 0960-7412

Abstract

SUMMARY: The non‐essential supernumerary maize ( Zea mays ) B chromosome (B) has recently been shown to contain active genes and to be capable of impacting gene expression of the A chromosomes. However, the effect of the B chromosome on gene expression is still unclear. In addition, it is unknown whether the accumulation of the B chromosome has a cumulative effect on gene expression. To examine these questions, the global expression of genes, microRNAs (miRNAs), and transposable elements (TEs) of leaf tissue of maize W22 plants with 0–7 copies of the B chromosome was studied. All experimental genotypes with B chromosomes displayed a trend of upregulated gene expression for a subset of A‐located genes compared to the control. Over 3000 A‐located genes are significantly differentially expressed in all experimental genotypes with the B chromosome relative to the control. Modulations of these genes are largely determined by the presence rather than the copy number of the B chromosome. By contrast, the expression of most B‐located genes is positively correlated with B copy number, showing a proportional gene dosage effect. The B chromosome also causes increased expression of A‐located miRNAs. Differentially expressed miRNAs potentially regulate their targets in a cascade of effects. Furthermore, the varied copy number of the B chromosome leads to the differential expression of A‐located and B‐located TEs. The findings provide novel insights into the function and properties of the B chromosome. Significance Statement: The non‐essential maize (Zea mays) B chromosome has wide applications in various genetic studies and genetic engineering of minichromosomes, yet little is known about how it impacts global gene expression. In the transcriptome analysis of maize plants with 0–7 copies, the B chromosome was found to impact the expression of thousands of A‐chromosome‐located genes in a predominant dosage‐insensitive manner while the B‐located genes generally show a proportional gene dosage effect. This property is in contrast to A chromosome aneuploidy, which modulates genes in a dosage‐sensitive fashion.