Histone Variant H3.3 Controls Arabidopsis Fertility by Regulating Male Gamete Development.

This article focuses on the role of the histone variant H3.3 in male gamete development in Arabidopsis thaliana. The study demonstrates that H3.3, encoded by three genes (HTR4, HTR5, and HTR8), is abundantly expressed in anthers and is essential for male fertility, as knockout mutants (h3.3–1) exhibit male sterility due to defects in pollen development and germination. Transcriptome and chromatin immunoprecipitation analyses reveal that H3.3 directly binds and activates a set of genes involved in reproductive processes, particularly those related to microgametogenesis. Furthermore, the deposition of H3.3 at target genes depends on the histone chaperone pathway mediated by Anti-Silencing Factor 1A/1B (ASF1A/1B) and Histone regulator A (HIRA), which is critical for proper transcriptional regulation during male gamete formation.