Legume pectate lyase required for root infection by rhizobia.
To allow rhizobial infection of legume roots, plant cell walls must be locally degraded for plant-made infection threads (ITs) to be formed. Here we identify a Lotus japonicus nodulation pectate lyase gene (LjNPL), which is induced in roots and root hairs by rhizobial nodulation (Nod) factors via activation of the nodulation signaling pathway and the NIN transcription factor. Two Ljnpl mutants produced uninfected nodules and most infections arrested as infection foci in root hairs or roots. The few partially infected nodules that did form contained large abnormal infections. The purified LjNPL protein had pectate lyase activity, demonstrating that this activity is required for rhizobia to penetrate the cell wall and initiate formation of plant-made infection threads. Therefore, we conclude that legume-determined degradation of plant cell walls is required for root infection during initiation of the symbiotic interaction between rhizobia and legumes.
John Innes Centre,  Norwich Research Park, Colney, Norwich NR4 7UH,  United Kingdom.
Fang
F
Xie
Jeremy D
JD
Murray
Jiyoung
J
Kim
Anne B
AB
Heckmann
Anne
A
Edwards
Giles E D
GE
Oldroyd
J Allan
JA
Downie
D000595:Amino Acid Sequence; D001483:Base Sequence; D004790:Enzyme Induction / Q000502:physiology; D016013:Likelihood Functions; D000070116:Lotus / Q000201:enzymology* / Q000254:growth & development / Q000382:microbiology*; D059128:Mesorhizobium / Q000235:genetics* / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D011133:Polysaccharide-Lyases / Q000096:biosynthesis* / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053204:Root Nodules, Plant / Q000382:microbiology*
D011133:Polysaccharide-Lyases; C023911:pectate lyase