Uniparental and transgressive expression of ?-zeins in maize endosperm of o2 hybrid lines.

ABSTRACT: The ?-zein gene family encodes the most abundant storage proteins of maize (Zea mays) endosperm. Members of this family are expressed in a parent-of-origin manner. To characterize this phenomenon further, we investigated the expression of a subset of ?-zein polypeptides in reciprocal crosses between o2 lines that were characterized by a simplified ?-zein pattern. Maize lines that suppressed the expression of ?-zeins when used as female parents were identified. The suppression was cross-specific, occurring only when specific genetic backgrounds were combined. Four ?-zein sequences that were sensitive to uniparental expression were isolated. Molecular characterization of these ?-zeins confirmed that their expression or suppression depended on the genetic proprieties of the endosperm tissue instead of their parental origin. DNA methylation analysis of both maternally and paternally expressed ?-zeins revealed no clear correlation between this epigenetic marker and parent-of-origin allelic expression, suggesting that an additional factor(s) is involved in this process. Genetic analyses revealed that the ability of certain lines to suppress ?-zein expression was unstable after one round of heterozygosity with non-suppressing lines. Interestingly, ?-zeins also showed a transgressive expression pattern because unexpressed isoforms were reactivated in both F2 and backcross plants. Collectively, our results suggest that parent-of-origin expression of specific ?-zein alleles depends on a complex interaction between genotypes in a manner that is reminiscent of paramutation-like phenomena.

SUBMITTER: Castelli S 

PROVIDER: S-EPMC6237297 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature