Flowering time is an important agronomic trait that contributes to fitness in plants. However, the genetic basis of flowering time has not been extensively studied in pepper. To understand the genetics underlying flowering time, we constructed an F2 population by crossing a spontaneous early flowering mutant and a late-flowering pepper line. Using bulked segregant RNA-seq, a major locus controlling flowering time in this population was mapped to the end of chromosome 2. An APETALA2 (AP2) homolog (CaFFN) cosegregated with flowering time in 297 individuals of the F2 population. A comparison between the parents revealed a naturally occurring rare SNP (SNP2T > C) that resulted in the loss of a start codon in CaFFN in the early flowering mutant. Transgenic Nicotiana benthamiana plants with high CaFFN expression exhibited a delay in flowering time and floral patterning defects. On the other hand, pepper plants with CaFFN silencing flowered early. Therefore, the CaFFN gene acts as a flowering repressor in pepper. CaFFN may function as a transcriptional activator to activate the expression of CaAGL15 and miR156e and as a transcriptional repressor to repress the expression of CaAG, CaAP1, CaSEP3, CaSOC1, and miR172b based on a qRT-PCR assay. Direct activation of CaAGL15 by CaFFN was detected using yeast one-hybrid and dual-luciferase reporter assays, consistent with the hypothesis that CaFFN regulates flowering time. Moreover, the CaFFN gene association analysis revealed a significant association with flowering time in a natural pepper population, indicating that the CaFFN gene has a broad effect on flowering time in pepper. Finally, the phylogeny, evolutionary expansion and expression patterns of CaFFN/AP2 homologs were analyzed to provide valuable insight into CaFFN. This study increases our understanding of the involvement of CaFFN in controlling flowering time in pepper, thus making CaFFN a target gene for breeding early maturing pepper.

中文翻译：

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APETALA2 同源物 CaFFN 调节辣椒的开花时间

开花时间是一个重要的农艺性状，有助于植物的适应性。然而，辣椒开花时间的遗传基础尚未得到广泛研究。为了了解开花时间背后的遗传学，我们构建了一个 F2通过杂交一个自发的早花突变体和晚花辣椒系来进行种群。使用批量分离 RNA-seq，该种群中控制开花时间的主要基因座被定位到 2 号染色体的末端。APETALA2(AP2) 同系物 (钙离子) 在 F 的 297 个个体中与开花时间共同分离2人口。父母之间的比较揭示了一个自然发生的稀有 SNP (SNP2T > C)，导致起始密码子丢失钙离子在早期开花突变体中。转基因本氏烟草高的植物钙离子表达表现出开花时间延迟和花型缺陷。另一方面，辣椒植物钙离子沉默开花早。因此，钙离子基因在辣椒中充当开花抑制因子。CaFFN 可作为转录激活因子激活CaAGL15和miR156e并作为转录抑制因子来抑制钙调,钙AP1,CaSEP3,CaSOC1， 和miR172b基于 qRT-PCR 分析。直接激活CaAGL15使用酵母单杂交和双荧光素酶报告基因测定法检测到 CaFFN，这与 CaFFN 调节开花时间的假设一致。此外，钙离子基因关联分析揭示了天然辣椒种群的开花时间与开花时间显着相关，表明钙离子基因对辣椒开花时间有广泛影响。最后，系统发育、进化扩展和表达模式CaFFN/AP2分析同源物以提供有价值的见解钙离子. 这项研究增加了我们对参与的理解钙离子控制辣椒的开花时间，从而使钙离子选育早熟辣椒的靶基因。