MtNRLK1, a CLAVATA1-like leucine-rich repeat receptor-like kinase upregulated during nodulation in Medicago truncatula

Abstract

Peptides are signaling molecules regulating various aspects of plant development, including the balance between cell division and differentiation in different meristems. Among those, CLAVATA3/Embryo Surrounding Region-related (CLE-ESR) peptide activity depends on leucine-rich-repeat receptor-like-kinases (LRR-RLK) belonging to the subclass XI. In legume plants, such as the Medicago truncatula model, specific CLE peptides were shown to regulate root symbiotic nodulation depending on the LRR-RLK SUNN (Super Numeric Nodules). Amongst the ten M. truncatula LRR-RLK most closely related to SUNN, only one showed a nodule-induced expression, and was so-called MtNRLK1 (Nodule-induced Receptor-Like Kinase 1). MtNRLK1 expression is associated to root and nodule vasculature as well as to the proximal meristem and rhizobial infection zone in the nodule apex. Except for the root vasculature, the MtNRLK1 symbiotic expression pattern is different than the one of MtSUNN. Functional analyses either based on RNA interference, insertional mutagenesis, and overexpression of MtNRLK1 however failed to identify a significant nodulation phenotype, either regarding the number, size, organization or nitrogen fixation capacity of the symbiotic organs formed.

Overexpression of the peanut CLAVATA1-like leucine-rich repeat receptor-like kinase AhRLK1 confers increased resistance to bacterial wilt in tobacco

“…S3). CLAVATA1 mainly plays an important role in shoot and root meristem and flower development in Arabidopsis (Clark et al , 1997), but participates in the signaling pathway during nodulation in Medicago truncatula (Laffont et al , 2018). Interestingly, a mutant of the CLAVATA1 ( CLV1 ) gene conferred enhanced disease resistance to bacterial wilt (Hanemian et al , 2016).…”

“…The full length coding sequence of this gene was isolated by RACE, and it contained 12 conserved LRRs and a kinase domain. Phylogenetic analysis showed that it was similar to CLAVATA1 , which is responsible for shoot and root meristem development and other functions (Clark et al , 1993, 1997; Williams and De Smet, 2013; Hanemian et al , 2016; Laffont et al , 2018). Microarray data showed that the three unigenes in the AhRLK1 family were expressed most strongly in stem and roots, and only traces were found in the embryo and pericarp (Fig.…”