Multiple trans-sensing interactions affect meiotically heritable epigenetic states at the maize pl1 locus.

Area of Science:

• Plant genetics
• Epigenetics
• Gene regulation

Background:

• Specific maize purple plant1 (pl1) alleles interact to cause heritable changes in gene regulation.
• These changes are observed as differences in anthocyanin pigmentation.
• Transcriptionally repressed states (Pl') of Pl1-Rhoades alleles are stable and can heritably alter highly expressed states (Pl-Rh).

Purpose of the Study:

• To identify cis-linked features of Pl1-Rhoades responsible for trans-sensing behaviors.
• To investigate the role of PL1 protein in maintaining these epigenetic states.
• To understand the mechanisms underlying Pl1-Rhoades epigenetic regulation.

Main Methods:

• Genetic testing of a pl1 allelic series.
• Analysis of ethyl-methanesulfonate-induced and spontaneous Pl1-Rhoades derivatives.
• Assessment of small RNA species associated with the pl1 gene.

Main Results:

• Two potentially separate cis-linked features were identified: one for repression of Pl-Rh and another for stabilizing Pl' in trans.
• Truncated PL1 peptides did not affect these functions, suggesting PL1 is not a trans-acting factor.
• Both functions were impaired in a derivative lacking detectable pl1 RNA, and Pl'-like states could repress other alleles non-heritably.

Conclusions:

• Cis-linked features, not the PL1 peptide itself, mediate the trans-sensing behaviors of Pl1-Rhoades alleles.
• The stability of the Pl' state is linked to the presence of detectable pl1 RNA.
• Interactions between transcriptional elements likely underlie the epigenetic behaviors of Pl1-Rhoades.