Environmental programming of heritable epigenetic changes in paramutant r-gene expression using temperature and light at a specific stage of early development in maize seedlings.

Different heritable expression-states were programmed into R alleles from R/R-1st heterozygotes under different temperature conditions applied during a developmental period in which flowering is induced. At maturity, R-allele expressions in test crosses of male gametes derived from R/R-1st seedlings raised 15 days in 32 degrees and continuous light conditions differed significantly from those of sib seedlings raised for 15 days in 22 degrees and continuous light conditions and shifted to six 12-hr light-dark cycles, day 16-21. This experiment provides the first evidence in higher organisms that environmental conditions, applied at a specific stage of development cause a heritable change in a specific allele expression. My earlier evidence required a statistical analysis for demonstrating heritable change; I present photographic evidence of this environmental effect on four R alleles.