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Article|01 Nov 2021|OPEN
The APETALA2 homolog CaFFN regulates flowering time in pepper
Xinjie Yuan1,2, Rong Fang1, Kunhua Zhou1, Yueqin Huang1, Gang Lei1, Xiaowu Wang2, & Xuejun Chen1,
1Institute of Vegetables and Flowers, Jiangxi Academy of Agricultural Sciences, 330200 Nanchang, China
2Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, 100081 Beijing, China

Horticulture Research 8,
Article number: 208 (2021)
doi: 10.1038/hortres.2021.208
Views: 17

Received: 01 Dec 2020
Revised: 07 Jun 2021
Accepted: 13 Jun 2021
Published online: 01 Nov 2021

Abstract

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.