Fruchtkoerperentwicklung von hoeheren Basidiomyceten unter dem Einfluss der Schwerelosigkeit (D-2-Mission) Abschlussbericht

Abstract

The project aimed at the gravitropism and gravimorphogenesis in basidiomycetous fungi. Fruiting body development of Flammulina velutipes was optimized and gravitropism was analyzed at 1xg, under the conditions of weightlessness, during clinorotation and during hyper-g on a centrifuge. When a fruiting body is shifted to the horizontal position, it performs a negative gravitropic reorientation within 12 h by differential elongation growth of the apical growth zone. In clinostat experiments the threshold g-stimulus could be determined to be approximately 1x10"-"4 xg. Fruiting bodies growing in weightlessness during the D-2-mission exhibited random orientation. The stipes showed gravimorphogenetical changes such as helical twisting and a flattened diameter. This could not be observed in clinostat experiments. When primordia were centrifuged in the orbit they showed normal negative gravitropic behaviour. The gravitropic stimulus is perceived in the upper 3-5 mm of the stipe. The cap is not required. The elongation growth is controlled by a growth hormone synthesized in the cap region, which is translocated to the upper stipe where it promotes elongation. This mycohormone is proposed to be differentially distributed in the gravisensitive transition zone between cap and stipe where it triggers differential growth during unilateral gravistimulation. On the ultrastructural level statoliths could not be demonstrated. (orig./AKF)SIGLEAvailable from TIB Hannover: F95B649 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany); Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA) GmbH, Bonn (Germany)DEGerman