The MFs Pattern In Mesophyll Protoplast Of Wheat And Its Response To Elicitor From Wheat Leaf Rust Fungus

Microfilaments (MF5) exit extensively in all eukaryotic cell as major components of cytoskeleton .They are involved in many essential cellular functions. Now it is still absent form the reports about MFs in the mesophyll of wheat. In this paper, the mesophyll protoplasts of wheat (MPW) were isolated using cellulase and pectolase digestion. By the chemcal and fluorescent (FITC-phalloidin) labelling, the MFs pattern in MPW a investigated under the confocal laser scanning microscope (CLSM) .The studies on the MFs showed that there exit dense actin filament bundles in MPW and they twine around the chloroplasts to form a network. On the basis of above experiment, the MFs pattern in MPW from cv.Lovrin 10 and from cv.5389 were investigated when the MPW were treated by intercellular washing fluid (IWF) or germ tube extract (GTE). And during the treatment, the hydrogen peroxide (H2O2) burst in MPW was monitored by the 27 dichlorodihydrofluorescein Diacetate(DCDHDA),a fluorescent indicator of H2O2 the vigor of MPW was monitored by the fluorescein diacetate(FDA),a fluorescent indicator of cell vigor ; the effects on the H202 burst and the vigor ae investigated after the MPW pretreated with Cytochalasin D(CD). The results are given as following: (1) During the treatment ,the MFs pattern in MPW from Lovrin 10(incompatible with leaf rust race 162) was maintained as the same as that before treatment; while the MFs pattern in MPW from 5389(compatible with leaf rust race 162) disassembled, and then disappeared, lastly reassembled in some MPW. These results seem to suggest that a proper form of MFs (the filamentous state of actin)is necessary to express the disease-resistant mechanisms. (2) The H202 burst in MPW from Lovrin 10 increased more markedly than that from 5389 after treatment by IWF . The H202 burst in MPW from Lovrin 10 was quenched after the MPW were pretreated by CD. These results seem to suggest that the proper form of MFs profits the H202 burst. (3) With the H202 burst, the vigor of MPW from Lovrin 10 decreased more quickly than that from 5389. The decrease of the vigor of MPW imply the hypersensitive reaction(HR) had been induced. The vigor of MPW from Lovrin 10 decreased less quickly when the MPW were pretreatment with CD, which suggest that the MFsadjust the HR by affecting the H202 burst. (4) As elicitor ,the GTE showed the same effects as the IWF did in many phases. However, there were some differences between them. GTE could quench the H202 burst at the early stage of trentment, suggesting that there is not only elicitor but also inhibitor in GTE. To sum up all above mentioned, it is concluded that the proper pattern of MFs is necessary to express disease resistance mechanisms.