Full establishment of arbuscular mycorrhizal symbiosis in rice occurs independently of enzymatic jasmonate biosynthesis.

Caroline Gutjahr,Heike Siegler,Ken Haga,Moritoshi Iino,Uta Paszkowski,Richard A Wilson

doi:10.1371/journal.pone.0123422

Abstract

Development of the mutualistic arbuscular mycorrhiza (AM) symbiosis between most land plants and fungi of the Glomeromycota is regulated by phytohormones. The role of jasmonate (JA) in AM colonization has been investigated in the dicotyledons Medicago truncatula, tomato and Nicotiana attenuata and contradicting results have been obtained with respect to a neutral, promotive or inhibitory effect of JA on AM colonization. Furthermore, it is currently unknown whether JA plays a role in AM colonization of monocotyledonous roots. Therefore we examined whether JA biosynthesis is required for AM colonization of the monocot rice. To this end we employed the rice mutant constitutive photomorphogenesis 2 (cpm2), which is deficient in JA biosynthesis. Through a time course experiment the amount and morphology of fungal colonization did not differ between wild-type and cpm2 roots. Furthermore, no significant difference in the expression of AM marker genes was detected between wild type and cpm2. However, treatment of wild-type roots with 50 μM JA lead to a decrease of AM colonization and this was correlated with induction of the defense gene PR4. These results indicate that JA is not required for AM colonization of rice but high levels of JA in the roots suppress AM development likely through the induction of defense.

Highlights

The phythormone jasmonic acid (JA) has long been known to be involved in defense against pests such as leaf chewing insects and pathogens such as necrotrophic microbes [1,2,3]
This deletion leads to a frameshift and a change in amino acid sequence making it highly unlikely that the resulting protein can still contribute to JA biosynthesis
Since JA-biosynthesis and—sensitivity are dependent on the light environment [31,32,33,34] we considered that under the light conditions applied in our phytochamber (12/12h day night cycle, 400μmoles m-2 s-1) JA-levels or—sensitivity in the wild type might be too low to reveal a significant difference in arbuscular mycorrhiza (AM) colonization by Rh. irregularis between wild-type and the JAdeficient mutant cpm2

Summary

Introduction

The phythormone jasmonic acid (JA) has long been known to be involved in defense against pests such as leaf chewing insects and pathogens such as necrotrophic microbes [1,2,3]. On the other hand JA and its mimick coronatine promote colonization of biotrophic pathogens by counteracting salicylic acid (SA) signaling which plays an important role in defense against. Rice Arbuscular Mycorrhiza Is Independent of Jasmonate Biosynthesis

Methods

Results

Conclusion