title: Rhizobial infection does not require cortical expression of upstream common symbiosis genes responsible for the induction of Ca(2+) spiking.
abstract: For the establishment of an effective root nodule symbiosis, a coordinated regulation of the infection processes between the epidermis and cortex is required. However, it remains unclear whether the symbiotic genes identified so far are involved in epidermal and/or cortical infection, e.g. epidermal and cortical infection thread formation or cortical cell division. To analyze the symbiotic gene requirements of the infection process, we have developed an epidermis-specific expression system (pEpi expression system) and examined the symbiotic genes NFR1, NFR5, NUP85, NUP133, CASTOR, POLLUX, CCaMK, CYCLOPS, NSP1 and NSP2 for involvement in the infection process in the epidermis and cortex. Our study shows that expression of the upstream common symbiosis genes CASTOR, POLLUX, NUP85 and NUP133 in the epidermis is sufficient to induce formation of infection threads and cortical cell division, leading to the development of fully effective nodules. Our system also shows a requirement of CCaMK, CYCLOPS, NSP1 and NSP2 for the entire nodulation process, and the different contributions of NFR1 and NFR5 to cortical infection thread formation. Based on these analyses using the pEpi expression system, we propose a functional model of symbiotic genes for epidermal and cortical infection.
authors: Division of Plant Sciences, National Institute of Agrobiological Sciences, 2-1-2 Kannon-dai, Tsukuba, 305-8602, Japan.
authors: Teruyuki
authors: T
authors: Hayashi
authors: Yoshikazu
authors: Y
authors: Shimoda
authors: Shusei
authors: S
authors: Sato
authors: Satoshi
authors: S
authors: Tabata
authors: Haruko
authors: H
authors: Imaizumi-Anraku
authors: Makoto
authors: M
authors: Hayashi
mesh_terms: D002118:Calcium / Q000378:metabolism*; D002455:Cell Division; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D005822:Genetic Vectors; D000070116:Lotus / Q000166:cytology / Q000235:genetics* / Q000382:microbiology / Q000502:physiology; D008954:Models, Biological; D009154:Mutation; D059372:Nucleotide Motifs; D009928:Organ Specificity; D010641:Phenotype; D019441:Plant Epidermis; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D012231:Rhizobium / Q000235:genetics* / Q000502:physiology; D053204:Root Nodules, Plant / Q000235:genetics; D013559:Symbiosis / Q000235:genetics*
chemical_list: D010940:Plant Proteins; D002118:Calcium
keywords: Lotus japonicus; cortical cell division; epidermis-specific expression system (pEpi expression system); infection threads; root cortex; root epidermis; root nodule symbiosis