Rhizobial and Mycorrhizal Symbioses in Lotus japonicus Require Lectin Nucleotide Phosphohydrolase, Which Acts Upstream of Calcium Signaling      

Abstract

(J.S., P.M.G.)Nodulation in legumes requires the recognition of rhizobially made Nod factors. Genetic studies have revealed that the perception of Nod factors involves LysM domain receptor-like kinases, while biochemical approaches have identified LECTIN NUCLEOTIDE PHOSPHOHYDROLASE (LNP) as a Nod factor-binding protein. Here, we show that antisense inhibition of LNP blocks nodulation in Lotus japonicus. This absence of nodulation was due to a defect in Nod factor signaling based on the observations that the early nodulation gene NODULE INCEPTION was not induced and that both Nod factor-induced perinuclear calcium spiking and calcium influx at the root hair tip were blocked. However, Nod factor did induce root hair deformation in the LNP antisense lines. LNP is also required for infection by the mycorrhizal fungus Glomus intraradices, suggesting that LNP plays a role in the common signaling pathway shared by the rhizobial and mycorrhizal symbioses. Taken together, these observations indicate that LNP acts at a novel position in the early stages of symbiosis signaling. We propose that LNP functions at the earliest stage of the common nodulation and mycorrhization symbiosis signaling pathway downstream of the Nod factor receptors; it may act either by influencing signaling via changes in external nucleotides or in conjunction with the LysM receptor-like kinases for recognition of Nod factor.

Building the interaction interfaces: host responses upon infection with microorganisms

“…Besides, several legume apyrases have been shown to positively be involved in RNS [36][37][38][39][40][41]. On the basis of these findings, Tanaka and associates have proposed the potential mechanism by which ecto-apyrases control rhizobial infection; activated ecto-apyrase(s) by NFs downregulates eATP levels, which in turn prevents generation of excess amount of ROS at root hairs that contributes to the regulation of IT rigidity [41].…”

Network of GRAS Transcription Factors Involved in the Control of Arbuscule Development inLotus japonicus

“…Genetic evidence shows that both symbioses share a common symbiosis signaling pathway (CSSP), which is composed of Leu-rich repeat receptor-like kinase (SYMBIOSIS RECEPTOR-LIKE KINASE [SYMRK] in Lotus japonicus/DOES NOT MAKE INFECTIONS2 [DMI2] in Medicago truncatula), cation channels (CASTOR and POLLUX in L. japonicus/DMI1 in M. truncatula), lectin nucleotide phosphohydrolase, calcium/calmodulindependent protein kinase (CCAMK; DMI3), an interacting protein of DMI3 (CYCLOPS in L. japonicus/ INTERACTING PROTEIN OF DOES NOT MAKE INFECTIONS3 [IPD3] in M. truncatula), components of the nuclear pore complex (NUP85, NUP133, and NENA), and the GRAS (for GIBBERELLIC ACID-INSENSITIVE, REPRESSOR of GAI, and SCARECROW [SCR]) transcription factor NODULATION SIGNALING PATH-WAY2 (NSP2) (Catoira et al, 2000;Endre et al, 2002;Stracke et al, 2002;Ané et al, 2004;Lévy et al, 2004;Imaizumi-Anraku et al, 2005;Kistner et al, 2005;Kanamori et al, 2006;Messinese et al, 2007;Saito et al, 2007;Gutjahr et al, 2008;Groth et al, 2010;Maillet et al, 2011;Roberts et al, 2013). SYMRK, nucleoporins, and cation channels are genetically upstream of calcium spiking, which is subsequently decoded by CCaMK (Saito et al, 2007;Charpentier et al, 2008;Kosuta et al, 2008).…”

A role for the mevalonate pathway in early plant symbiotic signaling

“…Because a knockout mutant of HMGR1 was not available, we used the same RNAi-based silencing strategy to investigate the role of HMGR1 in early symbiotic signaling. We analyzed the induction of nuclear-associated Ca 2+ spiking and the expression of the M. truncatula early nodulin 11 (ENOD11) gene, two early symbiotic responses that have been used extensively to study symbiotic signaling (29)(30)(31).…”