Question

Flowering Locus C (FLC) is a gene that is responsible for flowering in certain plants. FLC is expressed in new seedlings, which prevents flowering. Upon exposure to cold temperatures, FLC expression decreases and the plant flowers. FLC is regulated through epigenetic modifications. What type of epigenetic modifications are present in new seedlings and after cold exposure

Answer 1

- New seedlings: histone acetylation

- After cold exposure: histone methylation

Step-by-step explanation:

Vernalization is an adaptive mechanism whose objective is to ensure that flowering occurs only after winter (i.e., after cold conditions). In certain plants, this process (vernalization) suppresses the expression of genes that encode repressors of flowering. In Arabidopsis, vernalization is associated with histone modifications at FLC chromatin. The FLOWERING LOCUS C (FLC) is a MADS-box gene that acts as a repressor of flowering in Arabidopsis. Epigenetic modifications control the expression of the FLC gene. The FLC gene is expressed at low temperatures due to histone acetylation at FLC chromatin, and thereby the expression of FLC mRNA transcripts ensures that the Arabidopsis plant cannot flower. Subsequently, as the Arabidopsis plant is exposed to cold, FLC is repressed by the accumulation of trimethylation on lysine 27 of histone 3 (H3K27me3), thereby allowing it to flower when temperatures become warmer.