Nod factor perception: an integrative view of molecular communication during legume symbiosis

MtMKK5 inhibits nitrogen-fixing nodule development by enhancing defense signaling

“…Numerous studies have been conducted to identify the receptor protein complex that recognizes the nod factor released by nitrogenfixing rhizobia bacteria. Furthermore, key signaling components and genes involved in the connection with symbiotic signaling pathways have been identified exclusively (Cao et al 2017;Ghantasala and Roy Choudhury 2022). Plant hormones such as cytokinin and ethylene, as well as Ca 2+ -mediated transcriptional networks, have been identified as key initial cues for root nodules in these studies (Hamel et al 2006;Oldroyd and Downie 2008;Ryu et al 2012; Tsikou et al 2018).…”

“…The study of nitrogen-fixing root nodules is one of the essential areas of research for comprehending not only the agricultural significance of nitrogen fixation, but also the cellular response that determines the new fate of cells for novel differentiation (Ghantasala and Roy Choudhury 2022;Oldroyd and Downie 2008;Wang et al 2018). Numerous studies have been conducted to identify the receptor protein complex that recognizes the nod factor released by nitrogenfixing rhizobia bacteria.…”

“…The establishment of the nitrogen fixing symbiosis is contingent upon the effective formation of a root nodule, which is a specialized organ of the host legume plants that are responsible for supplying an ideal environment for symbiotic rhizobia (Cao et al 2017). Recent advances in our understanding of the molecular mechanisms underlying the symbiotic interactions between legumes and rhizobia have led to the discovery of critical plant signaling components that are involved in the sensing of nod factors (NF) and its downstream signal transduction pathways (Ghantasala and Roy Choudhury 2022;Minguillon et al 2022). The characterization of nodulation mutants in model legume plants and the molecular cloning of the key genes encoding nodulation signaling components suggests that the signaling pathways for the nitrogen fixing symbiosis are evolutionary conserved in the legume family (Cao et al 2017;Ghantasala and Roy Choudhury 2022).…”

“…The nod factor accomplishes direct activation of its receptor complex, MtLYK3/NFP (LysM-receptor like kinase 3/Nod Factor Perception), and subsequent activation of downstream pathways (Geurts and Bisseling 2002;Limpens et al 2003;Moling et al 2014). These events rapidly induce nuclear Ca 2+ spiking and direct activation of MtDMI3 (Does-not-Make-Infections 3, a Ca 2+ -calmodulindependent kinase) to properly modulate the transcriptional network mediated by nodulation-related transcription factors including NSP1/2 (Nodulation Signaling Pathway 1/2), NIN and ERN1/2 (ERF Required for Nodulation 1/2, (Ane et al 2004;Ghantasala and Roy Choudhury 2022;Kalo et al 2005;Levy et al 2004;Minguillon et al 2022).…”

Friends in Arms: Flavonoids and the Auxin/Cytokinin Balance in Terrestrialization

“…While flavonoids’ role as bacterial chemoattractants has been recently questioned [ 140 , 141 , 142 ], it is well established that, under nitrogen-limiting conditions, legumes secrete flavonoids as root exudates to promote the activation of NodD transcription factors. The activation of NodDs induces the expression of Rhizobia Nod factors, subsequently signaling for the plant to engage in nodule development [ 139 , 140 , 143 ]. In turn, Rhizobial infection induces flavonoid synthesis, which is important for modulating auxin action in infected roots, further induction of bacterial Nod factor gene expression, and ensuring host-specific bacterial interactions [ 47 , 144 ].…”