Underground communication of root hormones by common mycorrhizal network between trifoliate orange and white clover

ABSTRACT

Common mycorrhizal network (CMN) links up several coexisting plant individuals via underground root communication for resource sharing, while it is not known whether phytohormones participate in such communication. A two-chambered rootbox separated through 37-μm mesh was used to establish the CMN by Diversispora spurca between trifoliate orange (TO) and white clover (WC). After 20 weeks of inoculation, the CMN was established, as evident from high mycorrhizal buildup under supplier (mycorrhizal inoculation) TO–target (non-mycorrhizal inoculation) WC association. This CMN was eventually responsible for the significant increase in plant biomass of these associated plants. CMN decreased root abscisic acid (ABA) level in supplier and target plants, but increased root indole-3-acetic acid (IAA) level in supplier plant alone. CMN mediated significantly higher gibberellins (GAs) and zeatin riboside (ZR) concentration in roots of target plant, leaving supplier plant unaffected. Root ZR was bidirectionally transferred through the CMN. A higher root methyl jasmonate (MeJA) concentration was observed in supplier WC–target TO or supplier TO–supplier WC association, indicating an unidirectional communication from WC to TO. It suggested that except IAA, GAs, brassinosteroid (BR), and ABA, root MeJA and ZR were apparently involved in the underground communication by CMN.

KEYWORDS:

• Arbuscular mycorrhizal fungi
• methyl jasmonate
• mycorrhizal hyphae
• zeatin riboside

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was supported by the Plan in Scientific and Technological Innovation Team of Outstanding Young, Hubei Provincial Department of Education (T201604).