A FERONIA-Like Receptor Kinase Regulates Strawberry (Fragaria × ananassa) Fruit Ripening and Quality Formation

Abstract

Ripening of fleshy fruits is controlled by a series of intricate signaling processes. Here, we report a FERONIA/FER-like receptor kinase, FaMRLK47, that regulates both strawberry (Fragaria × ananassa) fruit ripening and quality formation. Overexpression and RNAi-mediated downregulation of FaMRLK47 delayed and accelerated fruit ripening, respectively. We showed that FaMRLK47 physically interacts with FaABI1, a negative regulator of abscisic acid (ABA) signaling, and demonstrated that FaMRLK47 regulates fruit ripening by modulating ABA signaling, a major pathway governing strawberry fruit ripening. In accordance with these findings, overexpression and RNAi-mediated downregulation of FaMRLK47 caused a decrease and increase, respectively, in the ABA-induced expression of a series of ripening-related genes. Additionally, overexpression and RNAi-mediated downregulation of FaMRLK47 resulted in an increase and decrease in sucrose content, respectively, as compared with control fruits, and respectively promoted and inhibited the expression of genes in the sucrose biosynthesis pathway (FaSS and FaSPS). Collectively, this study demonstrates that FaMRLK47 is an important regulator of strawberry fruit ripening and quality formation, and sheds light on the signaling mechanisms underlying strawberry fruit development and ripening.

FaMYB44.2, a transcriptional repressor, negatively regulates sucrose accumulation in strawberry receptacles through interplay with FaMYB10

“…Studies investigating fruit ripening in strawberry have mainly focused on the mechanisms regulating anthocyanin accumulation ( Jiang and Joyce, 2003 ; Medina-Puche et al , 2014 ; Lin-Wang et al , 2014 ; Kadomura-Ishikawa et al , 2015 ). Several important regulatory proteins involved in anthocyanin accumulation have been identified, such as the protein kinases FaSnRK2.6 and FaMRLK47 and the transcription factors FaMYB1 and FaMYB10 ( Aharoni et al , 2001 ; Medina-Puche et al , 2014 ; Lin-Wang et al , 2014 ; Han et al , 2015 ; Kadomura-Ishikawa et al , 2015 ; Jia et al , 2017 ). We recently found that FaMRLK47, a negative regulator of anthocyanin accumulation, also functions as a positive regulator of sugar accumulation and that two important structural genes involved in sucrose accumulation, FaSPS3 (sucrose-6-phosphate synthase 3, gene31122 ) and FaSUS1 (sucrose synthase 1, gene12940 ), are key structural genes downstream of FaMRLK47 ( Jia et al , 2017 ).…”

Genomic structure and transcript analysis of the Rapid Alkalinization Factor (RALF) gene family during host-pathogen crosstalk in Fragaria vesca and Fragaria x ananassa strawberry

“…the MRLK mostly expressed in Fxa fruits [56] and with the Fxa LLG2 homolog (maker-Fvb3-4-snap-gene-34.65), show that the structural components necessary to bind MRLK47 and LLG2 are conserved in FanRALF3 (Fig 4B and 4C), suggesting a similar binding mechanism and complex formation. In Arabidopsis, AtRALF23 binding to FERONIA and LLG proteins leads to negative immunity response regulation, and this hypothesis can be tested by analysis of FanRALF3-1 binding to MRLK47 in fruits.…”

“…In a recent work, Jia et al [56] analyzed the expression of the woodland strawberry (F. vesca) Malectin Receptor Like Kinases (MRLK) also known as the Catharanthus roseus RLKlike proteins (RLK1Ls). F. vesca MRLKs are encoded by more than 60 genes, and more than 50% of these are expressed during fruit development.…”

Rapid Alkalinization Factor (RALF) gene family genomic structure and transcriptional regulation during host-pathogen crosstalk in Fragaria vesca and Fragaria x ananassa strawberry

“…Homology models of FaRALF3, in complex with FERONIA and LLG2 were generated using Modeller [49](v9.19) package using the complex of A. thaliana RALF23, LLG2 and FERONIA (PDB: 6a5e) as the template. ClustalX was used to create alignments of different components of the complex: FaRALF3 (GDR: snap_masked-Fvb2-2-processed-gene-47.50-mRNA-1), Fragaria x ananassa FERONIA MRLK47 (GDR: Uniprot: A0A1J0F5V4) and Fragaria x ananassa LLG2 (GDR: maker-Fvb3-4-snap-gene-34.65-mRNA-1) with the A. thaliana proteins in the A. thaliana complex.…”