Abstract

背景回顾：Plants age by developmental phase changes. In Arabidopsis, the juvenile to adult vegetative phase change (VPC) is marked by clear heteroblastic changes in leaves. VPC and the subsequent vegetative to reproductive phase change (RPC) are promoted by SQUAMOSA PROMOTOR BINDING PROTEIN-LIKE (SPL) transcription factors and repressed by miR156/157 targeting SPL transcripts. 

主要研究：By genetic, phenotypic and gene expression analyses we studied the role of the longevity promoting AT-HOOK MOTIF NUCLEAR LOCALIZED 15 (AHL15) and family members in SPL-driven plant ageing. 

结果1-AHL15突变和过表达表型：Arabidopsis ahl loss-of-function mutants showed accelerated VPC and flowering, whereas AHL15 overexpression delayed these phase changes. 

结果2-AHL15抑制SPL：Expression analysis and tissue-specific AHL15 overexpression revealed that AHL15 affects VPC and flowering time directly through its expression in the shoot apical meristem and young leaves, and that AHL15 represses SPL2/9/13/15 gene expression in a miR156/157-independent manner. 

结果3-AHL15与SPL构成的相互调节的反馈回路：The juvenile traits of spl loss-of-function mutants appeared to depend on enhanced expression of the AHL15 gene, whereas SPL activity prevented vegetative growth from axillary meristem by repressing AHL15 expression. 

结论：Our results place AHL15 and close family members together with SPLs in a reciprocal regulatory feedback loop that modulates VPC, flowering time and axillary meristem development in response to both internal and external signals. 

 摘 要 

植物会随着发育阶段的改变而变得成熟。在拟南芥中，童期向成年营养期转变（VPC）以叶片中明显的变化为标志。VPC以及随后营养期向生殖期转变（RPC）受到SPL转录因子的促进，同时受到能够靶向SPL转录本的miR156/157所抑制。本文中，作者通过遗传学、表型和基因表达分析，研究了长寿促进蛋白AHL15及其家族成员在SPL驱动的植物成熟中的作用。拟南芥ahl突变体表现出VPC和开花的加速，而AHL15过表达会导致这些发育时期的延后。通过对AHL15基因的表达分析及AHL15组织特异性过表达发现，茎尖分生组织和幼嫩叶片中AHL15的表达水平直接影响了VPC和开花时间，并且AHL15通过一个独立于miR156/157的方式抑制SPL2/9/13/15基因的表达。spl突变体的童期性状似乎依赖于AHL15基因的增强表达，而腋生分生组织中SPL通过抑制AHL15基因的表达来阻止营养生长。本文的研究结果表明AHL15及其家族成员与SPLs一起形成了一个相互调节的反馈回路，响应于植物内部发育和外部环境线索，控制童期向成年营养期转变、开花时间以及腋生分生组织发育。