POSSIBLE MECHANISMS OF MICROGRAVTTY INFLUENCE ON PLANT SUSCEPTIBLE TO INVASION BY FUNGAL PATHOGEN

摘要

An interaction between soybean Glycine max. L. (cv. Williams 82) seedlings and the fungal root rot Phytophthora sojae in microgravity for 6 days during the Collaborative Ukrainian/US experiment on board the space shuttle Columbia (STS-87) have been studied. To quantitatively measure the effects of microgravity on susceptibility of soybean seedlings to P. sojae, we used a system for growing seedlings in autoclavable pouches in the BRIC hardware. Seedlings were fixed on orbit for the further analysis by light and electron microscopy. The comparative uitrastructural study of both differentiated epidermal and parenchyma cells of cortex and meristematic cells of root was carried out for the first time. Moreover, the cell ultrastructure of P. sojae pathogen, which developed into plant cell in microgravity, has described. The different phases of plant cell destruction were revealed in the investigated tissues. It is established that the invasion of pathogen into cells and the destruction of cell-host in the root tissues have been increased in microgravity. Strengthening of fungal pathogen invasion into plant in microgravity is supposed to be due to an increase of growth of pathogen cells and the change of composition of plant cell wall under the influence of microgravity.