APETALA2‐like transcription factor in shoot architecture and perennial traits. APETALA2‐like transcription factor in shoot architecture and perennial traits

Polycarpic perennials maintain vegetative growth after flowering. PERPETUAL FLOWERING 1 (PEP1), the orthologue of FLOWERING LOCUS C (FLC) inArabis alpina regulates flowering and contributes to polycarpy in a vernalisation-dependent pathway. pep1 mutants do not require vernalisation to flower and have reduced return to vegetative growth as all of their axillary branches become reproductive. To identify additional genes that regulate flowering and contribute to perennial traits we performed an enhancer screen of pep1. Using mapping-by-sequencing, we cloned a mutant (enhancer of pep1-055, eop055), performed transcriptome analysis and physiologically characterised the role it plays on perennial traits in an introgression line carrying the eop055 mutation and a functional PEP1 wild-type allele. eop055 flowers earlier than pep1 and carries a lesion in the A. alpina orthologue of the APETALA2 (AP2)-like gene, TARGET OF EAT2 (AaTOE2). AaTOE2 is a floral repressor and acts upstream of SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE 5 (AaSPL5). In the wild-type background, which requires cold treatment to flower, AaTOE2 regulates the age-dependent response to vernalisation. In addition, AaTOE2 ensures the maintenance of vegetative growth by delaying axillary meristem initiation and repressing flowering of axillary buds before and during cold exposure. We conclude that AaTOE2 is instrumental in fine tuning different developmental traits in the perennial life cycle of A. alpina. Overall design: Refer to individual Series

多次结实多年生植物（Polycarpic perennials）在开花后仍可维持营养生长。持续开花1号（PERPETUAL FLOWERING 1, PEP1）是高山南芥（Arabis alpina）中开花位点C（FLOWERING LOCUS C, FLC）的同源基因，可通过依赖春化的通路调控开花过程，并参与多次结实性状的形成。pep1突变体无需春化即可开花，且由于所有腋生分枝均转为生殖生长，其恢复营养生长的能力下降。为鉴定更多调控开花并参与多年生性状形成的基因，我们对pep1突变体开展了增强子筛选实验。通过图位克隆结合测序技术，我们克隆得到一株突变体（pep1增强子055，enhancer of pep1-055, eop055），并在携带eop055突变与功能型PEP1野生型等位基因的渐渗系中，对该基因在多年生性状中的作用进行了转录组分析与生理学表征。eop055的开花时间早于pep1，其突变位点位于高山南芥中APETALA2（AP2）样基因TARGET OF EAT2的同源基因（AaTOE2）。AaTOE2是一种开花抑制因子，作用于SQUAMOSA启动子结合蛋白样5（SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE 5, AaSPL5）的上游。在需要低温处理才能开花的野生型背景中，AaTOE2调控植株对春化的年龄依赖性响应。此外，AaTOE2通过延迟腋生分生组织起始，并在低温处理前及处理过程中抑制腋芽开花，从而维持营养生长状态。综上，AaTOE2在高山南芥的多年生生活周期中，对多种发育性状起到精细调控的作用。实验整体设计：详见各系列数据集。