Rye supernumerary (B) chromosomes possess an accumulation mechanism involving the subtelomeric domain enriched by B chromosome specific DNA sequence families, D1100 and E3900. Pereira et al. show that presence of rye B chromosomes may protect pollen mother cells at meiosis against heat stress induced damage.
Heat resulted in equal up-regulation of heat shock protein Hsp101 transcripts in plants with zero or 2B chromosomes. A significant up-regulation of E3900 related transcripts occurred in 2B plants at meiotic prophase I, compared to in 0B plants that showed significantly greater heat induced nuclear anomalies. Bioinformatics revealed a high density of known heat responsive cis-regulatory elements within the E3900 sequence and a truncated variant, supporting stress induced response of transcription and a role for B chromosomes in the protection against heat stress induce damage.