Mycelium development and architecture, and spore production of Scutellospora reticulata in monoxenic culture with Ri T-DNA transformed carrot roots

Abstract

Mycelium development and architecture and spore production were studied in Scutellospora reticulata from single-spore isolates grown with Ri T-DNA transformed carrot root-organ culture in monoxenic system. Culture establishment, anastomosis occurrence and auxiliary cell development also were examined. Seventy percent of the pregerminated disinfected spores colonized the transformed carrot roots. After 8 mo, the average spore production was 56 (24–130) per 30 cm³ of medium. Of the spores produced, 75% germinated and produced new generations in monoxenic culture. The mycelium network was formed by thick light-brown hyphae, which exhibit two major architecture patterns related to either root colonization or resource exploitation, and lower-order hyphae, bearing auxiliary cells, branched absorbing structures (BAS), hyphal swellings (HS) and forming anastomoses. BAS were formed abundantly in extramatrical mycelium and frequently had HS resembling vesicles, a feature not previously reported in the Gigasporaceae, to the best of our knowledge. Few anastomosis were observed within the mycelium and most often corresponded to a healing mechanism that form hypha bridges to reconnect broken hyphae or overcoming obstructed areas within a hypha. Numerous auxiliary cells were produced during culture development and their role was inferred.

• anastomosis
• arbuscular mycorrhizal fungi
• auxiliary cell
• branched absorbing structures
• Gigasporaceae
• Glomeromycota
• hyphal swelling
• monoxenic culture

FAdeS was supported by the Brazilian Council for Scientific and Technological Development (CNPq) (grant No. 200850/98–9). SD was supported by the Belgian Federal Office for Scientific, Technical and Cultural affairs (OSTC, contract BCCM C2/10/007) and thanks the director of the MUCL for the facilities provided and continual encouragement. We also thank J. A. van Veen, G. A. Kowalchuk and two anonymous reviewers for their useful comments on the manuscript.PUBLICation 3152 of the NIOO-KNAW Netherlands Institute of Ecology.

Notes

2 Part of the Belgian Coordinated Collections of Micro-organisms (BCCM)