Transposon-induced inversions activate gene expression in Maize pericarp

Abstract

Chromosomal inversions can have considerable biological and agronomic impacts including disrupted gene function, change in gene expression and inhibited recombination. Here we describe the molecular structure and functional impact of six inversions caused by Alternative Transpositions between p1 and p2 genes responsible for floral pigmentation in maize. In maize line p1-wwB54, the p2 gene is expressed in anther and silk but not in pericarp, making the kernels white. We identified inversions in this region caused by transposition of Ac and fractured Ac (fAc) transposable elements. These inversions change the position of a p1 enhancer and activate the expression of p2 in the kernel pericarp, resulting in red kernel color. We hypothesize that these inversions place the p2 gene promoter near a p1 gene enhancer, thereby activating p2 expression in kernel pericarp.

Complex chromosomal rearrangements induced by transposons in maize

“…The null allele p1-wwB54 has a white kernel pericarp phenotype, and the p2 gene is not expressed in the pericarp (Sharma et al . 2021).…”

“…Some of the rearrangements previously studied are deletions (Zhang et al . 2006), inversions (Sharma et al . 2021), and Composite Insertions (Su et al .…”

“…2011). Even a single rearrangement event can have a dramatic effect on gene expression (Sharma et al . 2021).…”