Behaviours of urediospore germtube in Melampsora larici-populina on the leaf surface of Populus purdomii were studied by light microscope, scanning electron microscope （SEM）, transmission electron microscope （TEM）...Behaviours of urediospore germtube in Melampsora larici-populina on the leaf surface of Populus purdomii were studied by light microscope, scanning electron microscope （SEM）, transmission electron microscope （TEM）, and fluorescence microscope. Crab-like fusion cells on leaf surface, intercellular hyphal cells in leaf tissues, as well as nucleus states, were observed and counted up in this study. Under unsaturated humidity, 32% of germinated tubes fused into a distinguishable swollen crab-shaped cell at the merging site, and 10.5% of observed crab-like cells had more than three nuclei. Wedge-shaped mycelia developed and then penetrated the leaf surface directly, or indirectly through stomata. Tips of germtube passed through the intercellular cells of poplar leaves directly were found in TEM. Aniline blue dyeing also showed that the infecting hyphae could invade into the cuticle and epidemic cell wall directly. For the case of infection through stomata, there were two different situations. Short branches and wedge hyphae usually penetrated the leaf surface via opened stomata, whereas, some germtube branches and wedge hyphae penetrated leaves through the guard cell walls or stoma lips. In the latter case, the stomata were always closed. The samples from wild forestlands had the same fused cells and wedge hyphae, but the occurrence rate was much higher than that in the chamber. Even under the saturated air humidity, germtubes could roll back and formed fusion structure, or merged together with their tips. The fusion cells might centralize the plasma of merged germtubes and have a strong survival capacity to protect germtubes from dying under arid circumstances, and provide a chance of genetic variation as well.展开更多
To compare the differences in intertranslation space of ribosomal DNA （ITS） of Melampsora larici-populina, between the isolates from China and isolates from other countries, this study investigated ITS sequences and...To compare the differences in intertranslation space of ribosomal DNA （ITS） of Melampsora larici-populina, between the isolates from China and isolates from other countries, this study investigated ITS sequences and ITS polygenetic tree based on 11 isolates that were collected from 5 races in different parts of China. The results indicated that there was no difference among the ITS sequences of 11 isolates from China. The ITS sequence of isolates from China was more homogeneous with that of isolates from Britain compared with France, Germany, and Canada. Intersimple sequence repeat （ISSR） markers were also used to study the genetic division of Melampsora larici-populina, and the results showed that the 11 tested isolates could be divided into Western population and Northern population. Genetic diversity index of race C2 was significantly different from that of races C4, C3, and C1, and no significant differences were observed among the other races. Pathogenicity division of races must not harmonize with their genetic division, except race C2. The ITS region is conservative, and ITS sequence is not fit for studying the differences that existed among the races. ISSR marker can be used for intraspecies population study, and Melampsora larici-populina in China can be divided into two populations.展开更多
基金supported by grants from the National Natural Science Foundation of China (30771734)the Provincial Natural Science Foundation, China (Shaan2008C109)the Northwest A&F University Research Foundation, China (Z109021005)
文摘Behaviours of urediospore germtube in Melampsora larici-populina on the leaf surface of Populus purdomii were studied by light microscope, scanning electron microscope （SEM）, transmission electron microscope （TEM）, and fluorescence microscope. Crab-like fusion cells on leaf surface, intercellular hyphal cells in leaf tissues, as well as nucleus states, were observed and counted up in this study. Under unsaturated humidity, 32% of germinated tubes fused into a distinguishable swollen crab-shaped cell at the merging site, and 10.5% of observed crab-like cells had more than three nuclei. Wedge-shaped mycelia developed and then penetrated the leaf surface directly, or indirectly through stomata. Tips of germtube passed through the intercellular cells of poplar leaves directly were found in TEM. Aniline blue dyeing also showed that the infecting hyphae could invade into the cuticle and epidemic cell wall directly. For the case of infection through stomata, there were two different situations. Short branches and wedge hyphae usually penetrated the leaf surface via opened stomata, whereas, some germtube branches and wedge hyphae penetrated leaves through the guard cell walls or stoma lips. In the latter case, the stomata were always closed. The samples from wild forestlands had the same fused cells and wedge hyphae, but the occurrence rate was much higher than that in the chamber. Even under the saturated air humidity, germtubes could roll back and formed fusion structure, or merged together with their tips. The fusion cells might centralize the plasma of merged germtubes and have a strong survival capacity to protect germtubes from dying under arid circumstances, and provide a chance of genetic variation as well.
基金This paper is translated from its Chinese version in Scientia Agricultura Sinica.This study is financially supported by National Natural Science Foundation of China(30471394)Natural Science Foundation of Shaanxi Province,China(ShaanC113).
文摘To compare the differences in intertranslation space of ribosomal DNA （ITS） of Melampsora larici-populina, between the isolates from China and isolates from other countries, this study investigated ITS sequences and ITS polygenetic tree based on 11 isolates that were collected from 5 races in different parts of China. The results indicated that there was no difference among the ITS sequences of 11 isolates from China. The ITS sequence of isolates from China was more homogeneous with that of isolates from Britain compared with France, Germany, and Canada. Intersimple sequence repeat （ISSR） markers were also used to study the genetic division of Melampsora larici-populina, and the results showed that the 11 tested isolates could be divided into Western population and Northern population. Genetic diversity index of race C2 was significantly different from that of races C4, C3, and C1, and no significant differences were observed among the other races. Pathogenicity division of races must not harmonize with their genetic division, except race C2. The ITS region is conservative, and ITS sequence is not fit for studying the differences that existed among the races. ISSR marker can be used for intraspecies population study, and Melampsora larici-populina in China can be divided into two populations.
