Pre-exposure to a stress may alter the plant＇s cellular, biochemical, and/or transcriptional responses during future encounters as a ＂memory＇ from the previous stress. Genes increasing transcription in response to ...Pre-exposure to a stress may alter the plant＇s cellular, biochemical, and/or transcriptional responses during future encounters as a ＂memory＇ from the previous stress. Genes increasing transcription in response to a first dehydra- tion stress, but producing much higher transcript levels in a subsequent stress, represent the super-induced ＇transcription memory＇ genes in Arabidopsis thaliana. The chromatin environment （histone H3 tri-methylations of Lys 4 and Lys 27, H3K4me3, and H3K27me3） studied at five dehydration stress memory genes revealed existence of distinct memory- response subclasses that responded differently to CLF deficiency and displayed different transcriptional activities dur- ing the watered recovery periods. Among the most important findings is the novel aspect of the H3K27me3 function observed at specific dehydration stress memory genes. In contrast to its well-known role as a chromatin repressive mechanism at developmentally regulated genes, H3K27me3 did not prevent transcription from the dehydration stress- responding genes. The high H3K27me3 levels present during transcriptionally inactive states did not interfere with the transition to active transcription and with H3K4me3 accumulation. H3K4me3 and H3K27me3 marks function indepen- dently and are not mutually exclusive at the dehydration stress-responding memory genes.展开更多
文摘Pre-exposure to a stress may alter the plant＇s cellular, biochemical, and/or transcriptional responses during future encounters as a ＂memory＇ from the previous stress. Genes increasing transcription in response to a first dehydra- tion stress, but producing much higher transcript levels in a subsequent stress, represent the super-induced ＇transcription memory＇ genes in Arabidopsis thaliana. The chromatin environment （histone H3 tri-methylations of Lys 4 and Lys 27, H3K4me3, and H3K27me3） studied at five dehydration stress memory genes revealed existence of distinct memory- response subclasses that responded differently to CLF deficiency and displayed different transcriptional activities dur- ing the watered recovery periods. Among the most important findings is the novel aspect of the H3K27me3 function observed at specific dehydration stress memory genes. In contrast to its well-known role as a chromatin repressive mechanism at developmentally regulated genes, H3K27me3 did not prevent transcription from the dehydration stress- responding genes. The high H3K27me3 levels present during transcriptionally inactive states did not interfere with the transition to active transcription and with H3K4me3 accumulation. H3K4me3 and H3K27me3 marks function indepen- dently and are not mutually exclusive at the dehydration stress-responding memory genes.
