Somatic embryogenesis receptor-like kinase 5 in the ecotype Landsberg erecta of Arabidopsis is a functional RD LRR-RLK in regulating brassinosteroid signaling and cell death control

Abstract

In plants, LRR-RLKs play central roles in regulating perception of extracellular signals and initiation of cellular responses under various environmental challenges. Arabidopsis SERK genes, including SERK1 to SERK5, constitute a LRR-RLK sub-family. SERK1, SERK2, SERK3/BAK1, and SERK4/BKK1 have been well characterized to function as crucial regulators in multiple physiological processes such as brassinosteroid signaling, cell death control, pathogenesis, and pollen development. Despite extremely high sequence identity with BKK1, SERK5 is reported to have no functional overlapping with BKK1, which is previously identified to regulate BR and cell death control pathways, probably due to a natural mutation in a highly conserved RD motif in the kinase domain of SERK5 in Col-0 ecotype. Through a gene sequencing analysis in several Arabidopsis accessions, we are able to identify SERK5 in Landsberg erecta (Ler) genome encoding a LRR-RLK with an intact RD motif. Overexpression of SERK5-Ler partially suppresses the BR defective phenotypes of bri1-5 and bak1-3 bkk1-1, indicating SERK5-Ler functions as a positive regulator in BR signaling. Furthermore, the interaction between SERK5-Ler and BRI1 is confirmed by yeast two-hybrid and BiFC assays, and the genetic result showing that elevated expression of a kinase-dead form of SERK5-Ler causes a dominant-negative phenotype in bri1-5. In addition, overexpression of SERK5-Ler is capable of delaying, not completely suppressing, the cell death phenotype of bak1-3 bkk1-1. In this study, we first reveal that SERK5-Ler is a biologically functional component in mediating multiple signaling pathways.

RNA-seq Transcriptome Response of Flax (Linum usitatissimum L.) to the Pathogenic Fungus Fusarium oxysporum f. sp. lini

“…This gene is an ortholog of Arabidopsis ATG05940, which encodes a RPMI-induced protein kinase (RIPK), that activates effector triggered immunity (ETI; Liu et al, 2011). Other RLKs that showed increased transcript abundance 18 DPI (Supplementary Figure S5A) could be related to recognition of pathogen proteins or sugars (e.g., chitobiose), or to cell death and immunity, as is common with some SERK1 family members (Gao et al, 2009; Wu et al, 2015). …”

Perception of double‐stranded RNA in plant antiviral immunity

“…Members of the SERK co-receptor kinase family are well characterized partners of plasma membrane-localized pattern-recognition receptors (PRRs) during antimicrobial PTI (Albrecht et al, 2008;Heese et al, 2007;Karlova et al, 2006;Li, 2010;Li et al, 2018b;Roux et al, 2011;Santiago et al, 2013;Wu et al, 2015). However, as viruses are obligate intracellular biotrophs, the question arises how intracellularly produced dsRNAs and proteins come together with these receptors during antiviral PTI.…”

Ectopic expression of the Coffea canephora SERK1 homolog‐induced differential transcription of genes involved in auxin metabolism and in the developmental control of embryogenesis

“…AtSERK1 is the closest homolog to DcSERK (74% nucleotides, 92% amino acids), and AtSERK5 encodes a kinase that is rendered non‐functional by a mutation in the RD motif (arginine and aspartic acid motif), which is conserved in protein kinases (He et al ). However, a functional AtSERK5 with an intact RD motif is found in the Arabidopsis Landsberg erecta ecotype, which displays a functional overlap with AtSERK3 and AtSERK4 in brassinosteroid (BR) signaling and cell death control (Wu et al ).…”