Effect of arbuscular mycorrhizal fungi inoculation on root traits and root volatile organic compound emissions of Sorghum bicolor

Abstract

Volatile organic compounds (VOCs) emitted by plant roots have important functions that can influence the rhizospheric environment. The aim of this study was to examine the effects of arbuscular mycorrhizal (AM) fungi on the profile of root VOCs. Sorghum (Sorghum bicolor) plants were grown in pots inoculated with either Glomus mosseae or Glomus intraradices, which formed mycorrhiza with the roots. Control plants were grown in pots inoculated with sterile inoculum and did not form mycorrhiza. Forty-four VOCs were determined using headspace solid-phase microextraction (HS-SPME) and gas chromatography–mass spectrometry (GC-MS). Alkanes were the most abundant type of VOCs emitted by both mycorrhizal and non-mycorrhizal plants. Both the quantity and type of volatiles were dramatically altered by the presence of AM fungi, and these changes had species specificity. Compared with non-mycorrhizal plants, mycorrhizal plants emitted more alcohols, alkenes, ethers and acids but fewer linear-alkanes. The AM fungi also influenced the morphological traits of the host roots. The total root length and specific root length of mycorrhizal plants were significantly greater than those of non-mycorrhizal plants; however, both the incidence and length of root-hair were dramatically decreased. Our findings confirm that AM fungi can alter the profile of VOCs emitted by roots as well as the root morphology of sorghum plants, indicating that AM fungi have the potential to help plants adapt to and alter soil environments.