“春化”是植物继寒冬之后在春天获得根据环境提示来开花的能力的过程，是植物的一个关键适应性特征，对农业生产有较大影响。拟南芥开花抑制因子FLC在由Polycomb调控蛋白调节的一个过程中被“春化”关闭。
现在，FLC的非编码反义RNA转录体被发现存在于冷处理的种子中，并对温度变化有响应，这说明它们在低温感应和FLC沉默中有可能扮演一个角儿。这种类型的反义转录事件（源自基因的3′端）也许是调控相应“正义”转录的一个普遍机制。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 462, 799-802 (10 December 2009) | doi:10.1038/nature08618
Cold-induced silencing by long antisense transcripts of an Arabidopsis Polycomb target
Szymon Swiezewski1, Fuquan Liu1, Andreas Magusin1 & Caroline Dean1
1 John Innes Centre, Colney, Norwich, NR4 7UH, UK
Correspondence to: Caroline Dean1 Correspondence and requests for materials should be addressed to C.D.
Transcription in eukaryotic genomes generates an extensive array of non-protein-coding RNA, the functional significance of which is mostly unknown1. We are investigating the link between non-coding RNA and chromatin regulation through analysis of FLC?—?a regulator of flowering time in Arabidopsis and a target of several chromatin pathways. Here we use an unbiased strategy to characterize non-coding transcripts of FLC and show that sense/antisense transcript levels correlate in a range of mutants and treatments, but change independently in cold-treated plants. Prolonged cold epigenetically silences FLC in a Polycomb-mediated process called vernalization2. Our data indicate that upregulation of long non-coding antisense transcripts covering the entire FLC locus may be part of the cold-sensing mechanism. Induction of these antisense transcripts occurs earlier than, and is independent of, other vernalization markers3 and coincides with a reduction in sense transcription. We show that addition of the FLC antisense promoter sequences to a reporter gene is sufficient to confer cold-induced silencing of the reporter. Our data indicate that cold-induced FLC antisense transcripts have an early role in the epigenetic silencing of FLC, acting to silence FLC transcription transiently. Recruitment of the Polycomb machinery then confers the epigenetic memory. Antisense transcription events originating from 3′ ends of genes might be a general mechanism to regulate the corresponding sense transcription in a condition/stage-dependent manner.
