Wuschel-related homeobox5 gene expression and interaction of CLE peptides with components of the systemic control add two pieces to the puzzle of autoregulation of nodulation.
In legumes, the symbiotic nodules are formed as a result of dedifferentiation and reactivation of cortical root cells. A shoot-acting receptor complex, similar to the Arabidopsis (Arabidopsis thaliana) CLAVATA1 (CLV1)/CLV2 receptor, regulating development of the shoot apical meristem, is involved in autoregulation of nodulation (AON), a mechanism that systemically controls nodule number. The targets of CLV1/CLV2 in the shoot apical meristem, the WUSCHEL (WUS)-RELATED HOMEOBOX (WOX) family transcription factors, have been proposed to be important regulators of apical meristem maintenance and to be expressed in apical meristem "organizers." Here, we focus on the role of the WOX5 transcription factor upon nodulation in Medicago truncatula and pea (Pisum sativum) that form indeterminate nodules. Analysis of temporal WOX5 expression during nodulation with quantitative reverse transcription-polymerase chain reaction and promoter-reporter fusion revealed that the WOX5 gene was expressed during nodule organogenesis, suggesting that WOX genes are common regulators of cell proliferation in different systems. Furthermore, in nodules of supernodulating mutants, defective in AON, WOX5 expression was higher than that in wild-type nodules. Hence, a conserved WUS/WOX-CLV regulatory system might control cell proliferation and differentiation not only in the root and shoot apical meristems but also in nodule meristems. In addition, the link between nodule-derived CLE peptides activating AON in different legumes and components of the AON system was investigated. We demonstrate that the identified AON component, NODULATION3 of pea, might act downstream from or beside the CLE peptides during AON.
All-Russia Research Institute for Agricultural Microbiology, 196608 St. Petersburg, Russia.
Maria A
MA
Osipova
Virginie
V
Mortier
Kirill N
KN
Demchenko
Victor E
VE
Tsyganov
Igor A
IA
Tikhonovich
Ludmila A
LA
Lutova
Elena A
EA
Dolgikh
Sofie
S
Goormachtig
D060054:Agrobacterium / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002454:Cell Differentiation; D049109:Cell Proliferation; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000494:pharmacology; D046913:Medicago truncatula / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000382:microbiology*; D018519:Meristem / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000235:genetics / Q000378:metabolism*; D018532:Pisum sativum / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D055170:Plant Root Nodulation; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016961:Rhizobium leguminosarum / Q000254:growth & development; D053204:Root Nodules, Plant / Q000235:genetics / Q000378:metabolism / Q000382:microbiology*; D020579:Sinorhizobium / Q000254:growth & development; D013559:Symbiosis; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D018398:Homeodomain Proteins; D007210:Indoleacetic Acids; D009842:Oligopeptides; D010940:Plant Proteins; D014157:Transcription Factors