Jasmonate biosynthesis in legume and actinorhizal nodules

• • Jasmonic acid (JA) is a plant signalling compound that has been implicated in theregulation of mutualistic symbioses. In order to understand the spatial distributionof JA biosynthetic capacity in nodules of two actinorhizal species, Casaurina glauca and Datisca glomerata, and one legume, Medicago truncatula, we determined thelocalization of allene oxide cyclase (AOC) which catalyses a committed step inJA biosynthesis. In all nodule types analysed, AOC was detected exclusively inuninfected cells. • The levels of JA were compared in the roots and nodules of the three plantspecies. The nodules and noninoculated roots of the two actinorhizal species, andthe root systems of M. truncatula, noninoculated or nodulated with wild-type Sinorhizobium meliloti or with mutants unable to fix nitrogen, did not showsignificant differences in JA levels. However, JA levels in all plant organs examined increased significantly on mechanical disturbance. • To study whether JA played a regulatory role in the nodules of M. truncatula, composite plants containing roots expressing an MtAOC1-sense or MtAOC1-RNAi construct were inoculated with S. meliloti. Neither an increase nor reductionin AOC levels resulted in altered nodule formation. • These data suggest that jasmonates are not involved in the development andfunction of root nodules.

Ämnesord

NATURVETENSKAP  -- Biologi -- Botanik (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Botany (hsv//eng)

Nyckelord

allene oxide cyclase

Frankia

jasmonic acid

nitrogen fixation

Sinorhizobium

Plant physiology

Växtfysiologi

Plant Physiology

växtfysiologi

Publikations- och innehållstyp

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