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CERBERUS, a novel U‐box protein containing WD‐40 repeats, is required for formation of the infection thread and nodule development in the legume– Rhizobium symbiosis
Author(s) -
Yano Koji,
Shibata Satoshi,
Chen WenLi,
Sato Shusei,
Kaneko Takakazu,
Jurkiewicz Anna,
Sandal Niels,
Banba Mari,
ImaizumiAnraku Haruko,
Kojima Tomoko,
Ohtomo Ryo,
Szczyglowski Krzysztof,
Stougaard Jens,
Tabata Satoshi,
Hayashi Makoto,
Kouchi Hiroshi,
Umehara Yosuke
Publication year - 2009
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2009.03943.x
Subject(s) - biology , lotus japonicus , rhizobium , organogenesis , primordium , nodule (geology) , root hair , symbiosis , root nodule , microbiology and biotechnology , mutant , lotus , botany , gene , genetics , bacteria , paleontology
Summary Endosymbiotic infection of legume plants by Rhizobium bacteria is initiated through infection threads (ITs) which are initiated within and penetrate from root hairs and deliver the endosymbionts into nodule cells. Despite recent progress in understanding the mutual recognition and early symbiotic signaling cascades in host legumes, the molecular mechanisms underlying bacterial infection processes and successive nodule organogenesis are still poorly understood. We isolated a novel symbiotic mutant of Lotus japonicus , cerberus , which shows defects in IT formation and nodule organogenesis. Map‐based cloning of the causal gene allowed us to identify the CERBERUS gene, which encodes a novel protein containing a U‐box domain and WD‐40 repeats. CERBERUS expression was detected in the roots and nodules, and was enhanced after inoculation of Mesorhizobium loti . Strong expression was detected in developing nodule primordia and the infected zone of mature nodules. In cerberus mutants, Rhizobium colonized curled root hair tips, but hardly penetrated into root hair cells. The occasional ITs that were formed inside the root hair cells were mostly arrested within the epidermal cell layer. Nodule organogenesis was aborted prematurely, resulting in the formation of a large number of small bumps which contained no endosymbiotic bacteria. These phenotypic and genetic analyses, together with comparisons with other legume mutants with defects in IT formation, indicate that CERBERUS plays a critical role in the very early steps of IT formation as well as in growth and differentiation of nodules.