Journal of Plant Research

, Volume 113, Issue 4, pp 443-448

Characterization of Mycorrhizas Formed by Glomus sp. on Roots of Hypernodulating Mutants of Lotus japonicus

  • M Zakaria SolaimanAffiliated withFaculty of Bioresources, Mie University, Tsu, Mie, 514–8507 Japan
  • , Keishi SenooAffiliated withFaculty of Bioresources, Mie University, Tsu, Mie, 514–8507 Japan
  • , Masayoshi KawaguchiAffiliated withGraduate School of Arts and Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo, 153–8902 Japan
  • , Haruko Imaizumi-AnrakuAffiliated withNational Institute of Agrobiological Resources, Kannondai, Tsukuba, Ibaraki, 305–8602 Japan
  • , Shoichiro AkaoAffiliated withNational Institute of Agrobiological Resources, Kannondai, Tsukuba, Ibaraki, 305–8602 Japan
  • , Akiyoshi TanakaAffiliated withFaculty of Bioresources, Mie University, Tsu, Mie, 514–8507 Japan
  • , Hitoshi ObataAffiliated withFaculty of Bioresources, Mie University, Tsu, Mie, 514–8507 Japan

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Lotus

japonicus hypernodulating mutants, Ljsym78-1 and Ljsym78-2, by the arbuscular mycorrhizal fungus Glomus sp. was characterized. The mutants are defective in systemic autoregulation of nodulation and nitrate inhibition, and form an excess of nodules and lateral roots. The percent root length colonized by the arbuscular mycorrhizal fungi was significantly higher for the mutant than wild-type roots. Detailed assessment of the colonization indicated that the percentage of colonization by arbuscules was increased, but that by external hyphae, internal hyphae and vesicles was decreased, in the mutant roots compared with the wild-type. The succinate dehydrogenase activity of arbuscules, external hyphae and internal hyphae showed similar trends. In addition, the majority of individual arbuscules that formed on the mutant roots had a well-developed and seemingly tough morphology. The results suggest that mutation at the Ljsym78 locus positively stimulates the growth and activity of arbuscules, but leads to reduced growth and activity of hyphae. We report the first identification of Lotus japonicus mutants that show significantly increased arbuscule formation and termed these mutants Arb++.

Keywords: Arbuscular mycorrhiza, Hypernodulating mutants, Lotus japonicus, Mycorrhizal mutants