小麦叶锈菌在感病寄主上发育的组织病理学和超微结构研究

 应用荧光显微技术、微分干涉技术和生物电镜技术,系统地研究了小麦叶锈菌在感病寄主上的发育过程及其超微结构特征。小麦叶锈菌在感病品种上的发育过程可分为几个明显的阶段,即孢子的萌发、附着胞的形成、气孔下囊的分化、初生菌丝和次生菌丝的形成和生长、吸器母细胞和吸器的形成、夏孢子床和夏孢子堆的产生以及夏孢子的形成。小麦叶锈菌的胞间菌丝呈丝状,生长和分枝通常沿寄主细胞壁进行。胞间菌丝与寄主细胞的接触诱导了吸器母细胞的分化,吸器母细胞在与寄主细胞壁的接触部位发育形成入侵栓,穿透寄主细胞壁后于细胞内形成吸器。胞间菌丝和吸器母细胞均含有双核,而成熟吸器则含有单核。经常规染色后,胞间菌丝和吸器母细胞的壁与隔膜均可分辨出由多层构成。     

小麦与条锈病菌不亲和互作的超微结构

 采用条锈菌同一小种的野生型菌系和弱毒突变菌系,分别接种同一小麦品种的方法,研究了不亲和互作的超微结构特征。在不亲和互作中,条锈菌的胞间菌丝、吸器母细胞和吸器明显受抑。吸器可以在发育早期受抑坏死,也可迟滞至吸器体形成之后坏死。吸器外质膜严重皱褶,并出现孔洞,吸器外间质加宽,沉积大量电子致密物质。侵染位点的小麦叶肉细胞表现与过敏性坏死反应相关联的一系列变化。细胞壁内侧还出现乳突状或颗粒状沉积物等防御结构或物质。     

种衣剂17号包衣对小麦条锈菌影响的组织病理学研究

种衣剂１７号内含三唑醇等杀菌剂和其它化学成分，小麦种子用种衣剂包衣，出苗后一叶期接咱小麦条锈菌毒性小种，采用荧光染色技术和整叶透明技术，研究了种衣剂１７号对条锈菌在寄主内发育的影响。观察结果表明，该种衣剂对对叶表的夏孢子萌发和芽管入侵无明显影响，但可使菌丝扩展和菌丝分枝严重受抑，吸器母细胞和吸器形成的数目减少，每一侵染点的吸器一般不超过２个，并且对吸器具有致畸作用。在多数侵染点内可观察到寄主细胞坏     

内吸杀菌剂烯唑醇对小麦条锈菌和白粉菌发育影响的研究

 小麦幼苗分别用小麦条锈菌和白粉菌接种3天后,用内吸杀菌剂烯唑醇喷雾施药。电镜观察烯唑醇对条锈菌和白粉菌在寄主上发育的影响,结果表明,烯唑醇引起两种病菌和寄主细胞发生一系列变化。小麦条锈菌和白粉菌菌丝细胞壁的内层普遍不规则地加厚,菌丝细胞的隔膜发育受阻而成为畸形;两病菌的吸器外间质变宽,并沉积有电子致密度较高的物质。小麦条锈菌的部分吸器母细胞产生的畸形入侵栓,不能穿透寄主细胞壁,部分吸器不能正常发育,吸器体呈分枝状,不能完全扩张、膨大。此外,被侵小麦细胞所分泌的物质可将条锈菌吸器完全包围起来。小麦条锈菌和白粉菌以上的细胞学变化可能导致了它们进一步发育受阻。     

青杨叶锈病菌(Melampsora larici-populina Kleb.)侵染过程的超微结构研究

 采用电子显微镜技术对青杨叶锈病菌(Melampsora larici-populina Kleb.)的侵染过程进行了研究。发现该菌夏孢子萌发产生1~3个芽管,且具较多的树杈状分枝。芽管由气孔侵入,侵入前不形成明显的附着胞或仅个别芽管形成附着胞。芽管侵入气孔后在气孔腔内形成气孔下囊,再分化出圆形的膨大体而产生1~2支初生菌丝。初生菌丝在寄主细胞间扩展,与叶肉细胞壁接触后分化出吸器母细胞,吸器母细胞中的细胞器与胞间菌丝相同,双核。吸器母细胞产生侵入钉侵入叶肉细胞内部形成吸器,成熟吸器由细长具颈环的管状颈部和膨大的吸器体组成,此时胞间菌丝在吸器母细胞处分化出次生菌丝,在叶肉细胞间扩展形成次生菌落,产生孢子堆。病菌在寄主细胞间隙或沿寄主细胞壁延伸时,寄主细胞仍保持正常状态。     

多堆柄锈菌侵染不同抗性玉米的组织病理学研究

［目的］ 了解不同抗感玉米自交系对南方锈病的组织病理学反应,为今后筛选不同类型抗病自交系提供参考。［方法］ 采用曲利苯蓝透明染色法,以4个玉米自交系为材料,研究了玉米南方锈病致病菌—多堆柄锈菌在不同抗性材料上侵染过程的组织学特征。［结果］ 多堆柄锈菌侵入和定殖可以分为5个阶段：孢子萌发与芽管形成、附着胞形成、侵入细胞、胞内吸器产生、菌丝在细胞间扩展。在不同抗性的玉米材料上,病菌孢子萌发和芽管形成差别不明显,但侵入后病菌在不同抗性材料内的发育进程和发育程度具有显著差异。在抗病玉米材料上,病菌初生菌丝、吸器母细胞、次生菌丝的形成时间推迟,胞内吸器少,菌丝分枝少,菌丝生长缓慢。［结论］ 这些抗性特征与田间表现出的细胞过敏性坏死、叶片上夏孢子堆少的特征具有一致性。     

菜豆锈菌侵染过程的显微和超微观察

 本文报道了通过微分干涉衬显微镜、荧光显微镜及扫描电镜和透射电镜所观察到的菜豆锈菌的侵入和扩展过程。菜豆锈菌夏孢子萌发多产生1个芽管,偶尔也产生双芽管。芽管以气孔侵入为主,也可从表皮直接侵入。侵入前形成或不形成明显的附着胞。气孔侵入的芽管首先在气孔腔内形成气孔下囊,再进一步分化出圆形的膨大体,由膨大体产生1~2支初生菌丝。初生菌丝与叶肉细胞壁接触后分化出吸器母细胞,吸器母细胞进入叶肉细胞内部形成吸器。初生侵染菌丝在产生吸器母细胞的部位的后部产生分枝,形成次生侵染菌丝在叶肉细胞间蔓延。     

三唑酮拌种对小麦条锈病菌叶部侵染过程的影响

 供试小麦种子用干拌法施药,在一叶期接种小麦条锈菌(Puccinia striiformis West)毒性小种,用整叶透明染色方法研究三唑酮拌种对条锈菌叶部侵染过程的影响.结果表明,由初生吸器形成开始,三唑酮对吸器产生和菌落扩展表现出多方面的影响.拌种植株叶片中条锈菌侵染菌丝的生长和分枝严重受阻,吸器母细胞和吸器形成显著减少,菌落亦不再进一步分化,多数侵染点还出现寄主细胞坏死。这些组织病理学变化与抗病品种的过敏性坏死反应很相似.     

草莓品种对白粉病菌抗性的组织病理学研究

以4个生产上主栽草莓品种为试材,采用曲利苯兰透明染色法,系统研究了草莓白粉病菌在不同抗性草莓品种上侵染过程的组织学特征。结果表明,草莓白粉病菌的侵染过程可分为：分生孢子萌发、附着胞形成、侵入寄主产生吸器、菌丝扩展和分生孢子链产生。而草莓不同品种对白粉菌的抗性表现在附着胞产生后的各侵染阶段,随品种抗病性增强,病菌侵入率降低,吸器数目减少,菌丝扩展缓慢,分生孢子数目减少。     

小麦条锈菌夏孢子阶段核相状况的研究

 本文应用电镜和荧光染色技术对小麦条锈菌夏孢子阶段的细胞核相状况进行了系统研究。观察发现夏孢子通常为双核体,夏孢子萌发的芽管可为双核、三核或四核,但仍以双核芽管为主。尽管在胞间菌丝和吸器母细胞中可观察到典型的双核细胞,但胞间菌丝和吸器母细胞中的多核现象极为普遍。经连续切片观察证实,吸器的细胞核可为双核、三核、四核、五核和六核,一般以四核为主。夏孢子堆中的不同类型的细胞均为双核。上述研究结果表明,小麦条锈菌的细胞核相状况较为复杂,并且显然不向于其它锈菌。关于小麦条锈菌多核现象的生物学意义值得进一步研究。     

Histological investigation of stripe rust (Puccinia striiformis f.sp. tritici) development in resistant and susceptible wheat cultivars

The wheat cultivar Kariega expresses complete adult plant resistance against stripe rust, whereas cv. Avocet S is susceptible. Using confocal laser scanning microscopy, initial fungal penetration into flag leaves was identical in both cultivars, with directional germ-tube growth towards stomata that were penetrated without the formation of an appressorium, followed by differentiation of a substomatal vesicle, infection hyphae, haustorial mother cells and haustoria. During the following 4 days, further fungal development occurred more quickly in the resistant than in the susceptible cultivar. However, by 7 days postinoculation (dpi) the situation changed, with exponential growth of the pathogen occurring only in the susceptible line. Induced cellular lignification, a typical defence reaction of cereals, was observed at 4 dpi in the resistant cultivar, and 2 days later lignified tissue completely surrounded the fungal colonies. In the susceptible cultivar, isolated lignified host cells occurred at 6 dpi, and long, unbranched fungal hyphae outgrowing the resistance reaction were observed.     

Scanning electron microscopy study of infection structure formation of Puccinia graminis f.sp. tritici in host and non-host cereal species

The development of uredospore-derived infection structures of Puccinia graminis f.sp. tritici in wheat, barley, sorghum and maize was examined by scanning electron microscopy (SEM). Germ tubes grew over the leaf surface until a stoma was located. An appressorium formed over the stoma and the leaf was penetrated by an infection peg. Within the substomatal chamber of all species the infection peg developed a substomatal vesicle by 6 h post-inoculation (hpi). from which a primary infection hypha developed parallel to the long axis of the leaf. In wheat, barley and maize, when a primary infection hypha abutted onto a host cell, a septum was laid down between the tip of the hypha and the substomatal vesicle, delimiting a haustorial mother cell by 12 hpi; haustorial mother cells did not form in sorghum. Secondary infection hyphae arose on the substomatal vesicle side of the septum; infection did not progress further in maize, but in wheat and barley secondary infection hyphae branched, and proliferated intercellularly forming the fungal thallus. A haustorial mother cell was delimited when an intercellular hypha abutted onto a host cell. Infection sites with haustorial mother cells were observed at 12 hpi in barley and 24 hpi in wheat. In all four plant species, some atypical substomatal vesicle initials, substomatal vesicles and primary infection hyphae were observed.     

Histological studies of the expression of the Lr9, Lr20 and Lr28 alleles for resistance to leaf rust in wheat

The development of the leaf rust fungus ( Puccinia recondita f.sp. tritici ) in a susceptible cultivar and three other cultivars possessing the Lr9, Lr20 and Lr28 alleles for resistance was studied by light and fluorescence microscopy. Formation of the substomatal vesicle, intercellular hypha and the first haustorial mother cell was unaffected by resistance. Lr9 and Lr28 expression was rapid, first seen as early initiation of hyphal branching at 16 h after inoculation, then reduced haustorial diameters at 19 h. Limited host cell necrosis was seen immediately afterwards. Elongation of intercellular hyphae was reduced between 20 and 24 h, and virtually ceased by about 30 h. Numbers of infection sites with a second haustorial mother cell were briefly higher at 24 h. Reduced hyphal branching and haustorial mother cell numbers were seen at 20–24 h and 36 h respectively. Lr20 expression was not seen until 36 h when reduced hyphal branching was observed, accompanied by extensive host cell necrosis. Reduced haustorial mother cell numbers were detected at 48 h. Findings suggested a secondary role for host cell necrosis in the expression of the Lr9 and Lr28 alleles. Host necrosis may play a determinant role in Lr20- based expression.     

Resistance levels of cucumber to <Emphasis Type="Italic">Podosphaera xanthii</Emphasis> in a growth chamber are related to haustorial formation and hyphal branching frequency

To clarify relationships between powdery mildew resistance of cucumber and hyphal developmental state of the pathogen, haustorial formation and the hyphal branching frequency were compared among cucumber varieties that differ in resistance levels to powdery mildew pathogen Podosphaera xanthii. Cotyledons of four cultivars were inoculated with P. xanthii. By 2 days after inoculation, secondary haustoria had developed from the first hyphal cell that formed beside the conidium in susceptible cultivars. The fungus on susceptible cultivars also tended to have hyphal branches just after the hyphal cell producing haustoria.     

菜豆锈病菌侵染对寄主超微结构的作用及菜豆抗锈病的细胞学表现

 在电镜下观察发现,菜豆锈病菌侵染菜豆后,逐步对其超微结构产生影响:寄主细胞发生质壁分离;叶绿体变形;叶绿体的片层结构排列零乱;线粒体脊模糊不清,直至叶绿体解体;线粒体空泡化;少数细胞的细胞壁分解;不同细胞的细胞器堆积在一起。同时,病原菌的侵染激发了寄主抗病性的细胞学表现:供试的抗感菜豆品种都表现为在病原菌侵入位点的寄主细胞壁内侧有高电子致密物质沉积;与吸器母细胞接触的寄主细胞壁加厚以及在吸器颈周围有电子不透明物质形成。只是这3种反应在抗病品种中表现得更加强烈。此外,抗病品种中还有一些特有的抗性特征,如被侵染细胞及其相邻细胞的快速坏死,吸器母细胞侵入位点的寄主细胞壁外侧也有一种高电子致密物质沉积,抗病品种中真菌吸器周围聚集含大量线粒体的寄主细胞的细胞质,且吸器外基质比感病品种中的宽。     

The haustorial interface in a resistant interaction of Erysiphe pisi with Pisum sativum

The interface between Erysiphe pisi and pea cv. JI 1049 was studied at the ultrastructural and cytochemical levels and compared with those in two susceptible cultivars. Haustorial efficiencies, as indexed by the length of mycelium associated with each haustorium, and growth rates on the resistant and one susceptible cultivar were also compared.The interaction in the resistant cultivar differed from those in the susceptible cultivars in the following ways: (i) there was no contact between the host plasmalemma and the A neckband region; (ii) papillae were contiguous with the surface of the neck and thus were probably formed before haustoria and (iii) there appeared to be less polysaccharide in the extrahaustorial membrane. The extrahaustorial membrane in the resistant cultivar lacked ATPase activity, whereas the rest of the host plasmamembrane had normal activity.Each haustorium supported a significantly greater total hyphal length in the resistant than in the susceptible cultivars. Growth rates of superficial hyphae were very similar on the susceptible and resistant cultivars but there was a delay in the onset on hyphal growth on the resistant cultivar which correlated with the previously reported delay in formation of the first haustorium. In contrast to hyphal growth rates, the rate of haustorium production was significantly less in the resistant cultivar. It is proposed that resistance in cv. JI 1049 operates at the stages prior to haustorium formation, similarly to that in some non-host and partial resistance systems. Once formed, however, the function of the haustorium seems to be unimpaired, despite the observed interfacial differences.