Most seeds are shed as dry, dormant organisms that will only germinate and grow into a new plant when favorable environmental conditions are encountered. The switch from a quiescent dormant embryo into an actively growing seedling requires the timely reactivation and reprogramming of gene expression (Hilhorst and Karssen, 1992). Previous studies on the regulation of gene expression during seed germination focused mainly on the level of messenger RNA transcription. However, how chromatin influences the timely control of seed germination is largely unknown. RNA-binding proteins and chromatin-associated proteins are emerging as important regulators of gene expression during seed development and germination (Sajeev et al., 2022). In a new study, Deyue Yang, Fengli Zhao, and colleagues (2022) identified the role of the RNA-binding protein RZ-1 in a novel chromatin silencing mechanism that influences seed germination.

The authors found that mutation of the genes encoding RZ-1B and RZ-1C proteins (rz-1b rz-1c) lead to delayed seed germination and increased accumulation of the hormone abscisic acid (ABA). ABA is produced during seed development to inhibit precocious germination and is a major regulator of seed dormancy (Hilhorst and Karssen, 1992). To investigate the causes of altered ABA accumulation, the authors quantified gene expression in rz-1b rz-1c mutants and in a complementation line (RZ-1Cpro: GFP-RZ-1C) and found that several ABA biosynthesis and signaling genes (eg NCED6 and ABI3) were upregulated in the mutants. The authors then crossed rz-1b rz-1c with several ABA-related mutants and observed full recovery of the delayed germination phenotype in the mutant (Figure). This indicated that