Variegated phenotype and developmental methylation changes of a maize allele originating from epimutation

Das, OP, Messing J.  1994.  

Journal:

Genetics

Volume Number:

136

Pages:

1121-41

Abstract:

Two instances of genetic transmission of spontaneous epimutation of the maize P-rr gene were identified. Transmission gave rise to two similar, moderately stable alleles, designated P-pr-1 and P-pr-2, that exhibited Mendelian behavior. Both isolates of P-pr conditioned a variable and variegated phenotype, unlike the uniform pigmentation conditioned by P-rr. Extensive genomic analysis failed to reveal insertions, deletions or restriction site polymorphisms between the new allele and its progenitor. However, methylation of the P gene was increased in P-pr relative to P-rr, and was greatly reduced (though not lost) in a revertant to uniform pigmentation. Variability in pigmentation conditioned by P-pr correlated with variability in transcript levels of the P gene, and both correlated inversely with variability in its methylation. Part of the variability in methylation could be accounted for by a developmental decrease in methylation in all tissues of plants carrying P-pr. We hypothesize that the variegated phenotype results from a general epigenetic pathway which causes a progressive decrease in methylation and increase in expression potential of the P gene as a function of cell divisions in each meristem of the plant. This renders all tissues chimeric for a functional gene; chimerism is visualized as variegation only in pericarp due to the tissue specificity of P gene expression. Therefore, this allele that originates from epimutation may exemplify an epigenetic mechanism for variegation in maize.

Notes:

0016-67318005419

Related External URL:

http://www.genetics.org/cgi/reprint/136/3/1121file://localhost/Users/messing/Documents/Lett.&Memos/New%20Text/Current%20Papers/Papers/1994/Das/DasGenetics%201994.pdfpapers://E07DE6F9-722A-4E29-ABD6-B44668802E4A/Paper/p219
Citation:
Das, OP, Messing J.  1994.  Variegated phenotype and developmental methylation changes of a maize allele originating from epimutation. Genetics. 136:1121-41.