提出问题：However, the genetic basis of its CF behavior is unknown.

主要发现：We demonstrated that Purple branch is heterozygous for the TFL1 homolog KSN. 

结果1-KSN等位基因：One KSN allele with a 9 kb Copia insertion was found to be identical to that from continuously flowering Rosa chinensis Old blush. The other allele was found to be a functional wild-type allele. 

结果2-表达模式：The overall expression of KSN was closely linked to the floral transition, and it was significantly repressed in continuously flowering Purple branch compared with OF Plena.

结果3-表观修饰：The promoter region of the normal KSN allele was hypermethylated, and histone methylation at H3H4, H3K9, and H3K27 of the KSN gene locus was modified in continuously flowering Purple branch. 

结果4-验证：Silencing of the DNA methyltransferase genes MET1 and CMT3 and the histone methyltransferase gene SUVR5 in Purple branch led to enhanced KSN expression, but silencing of the histone demethylase gene JMJ12 suppressed KSN expression.

结论：Therefore, the CF habit of Purple branch may be due to reduced expression of KSN caused by the halved dose and may be associated with epigenetic modifications together with retrotransposon insertions along the chromosome. Our study revealed a novel mechanism underlying the CF behavior of rose plants.

 摘 要 

玫瑰植物开花有两种，一种是一次开花，一种是持续开花。紫枝玫瑰是一种十分罕见的持续开花品种，在中国广泛种植。但是，关于紫枝玫瑰的持续开花习性还不是很清楚。作者发现紫枝玫瑰TFL1基因的同源基因KSN是一个杂合子。KSN的一个等位基因包含一个9 kb的Copia转座子插入，而这与另外一个持续开花的中国月季“Old blush”品种中的情况是一致的。而另外一个KSN等位基因是一个具有功能的野生型等位基因。KSN的整体表达与成花转变密切相关，并且与一次开花的品种Plena相比，在连续开花的紫色玫瑰中，KSN的表达明显受到抑制。正常KSN等位基因的启动子区域是被超甲基化的，而在持续开花的紫枝玫瑰中，KSN基因座的H3H4、H3K9和H3K27上组蛋白甲基化被修饰。紫枝玫瑰中DNA甲基转移酶基因MET1和CMT3以及组蛋白甲基转移酶基因SUVR5的沉默导致KSN基因的表达增强，而组蛋白去甲基酶基因JMJ12的沉默则抑制了KSN的表达。因此，紫枝玫瑰的持续开花习性可能是由于剂量减半引起的KSN基因表达降低所导致的，并可能与表观遗传修饰以及沿染色体的逆转录转座子插入有关。本文的研究揭示了一种新的机制，作用于紫枝玫瑰的持续开花习性。