Too much love, a root regulator associated with the long-distance control of nodulation in Lotus japonicus.
Legume plants tightly control the development and number of symbiotic root nodules. In Lotus japonicus, this regulation requires HAR1 (a CLAVATA1-like receptor kinase) in the shoots, suggesting that a long-distance communication between the shoots and the roots may exist. To better understand its molecular basis, we isolated and characterized a novel hypernodulating mutant of L. japonicus named too much love (tml). Compared with the wild type, tml mutants produced much more nodules which densely covered a wider range of the roots. Reciprocal grafting showed that tml hypernodulation is determined by the root genotype. Moreover, grafting a har1 shoot onto a tml rootstock did not exhibit any obvious additive effects on the nodule number, which was further supported by double mutational analysis. These observations indicate that a shoot factor HAR1 and a root factor TML participate in the same genetic pathway which governs the long-distance signaling of nodule number control. We also showed that the inhibitory effect of TML on nodulation is likely to be local. Therefore, TML may function downstream of HAR1 and the gene product TML might serve as a receptor or mediator of unknown mobile signal molecules that are transported from the shoots to the roots.
Magori
Shimpei
S
Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Oka-Kira
Erika
E
Shibata
Satoshi
S
Umehara
Yosuke
Y
Kouchi
Hiroshi
H
Hase
Yoshihiro
Y
Tanaka
Atsushi
A
Sato
Shusei
S
Tabata
Satoshi
S
Kawaguchi
Masayoshi
M
D018506:Gene Expression Regulation, Plant / Q000502:physiology; D005838:Genotype; D000070116:Lotus / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D055170:Plant Root Nodulation / Q000502:physiology*; D018517:Plant Roots / Q000378:metabolism*
D010940:Plant Proteins