首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到10条相似文献,搜索用时 218 毫秒
1.
Treatment of wheat leaves with heptanoyl salicylic acid (HS) and trehalose at concentrations of 0.1 and 15 g l(-1), prior to fungal inoculation, resulted in 40% and 60% protection, respectively, against powdery mildew. The total lipid composition of Blumeria graminis f.sp. tritici (Bgt) conidia, the causal agent of wheat powdery mildew, was compared when produced on wheat leaves, respectively, untreated and treated with the two elicitors, HS and trehalose. An obvious effect was observed on lipid composition (sterol and fatty acid (FA)) of Bgt conidia produced on wheat leaves treated with HS. A total of 16 FA (C12-C24 saturated and unsaturated) as well as unusual methoxylated Fatty Acids (mFA) (3-methoxydocosanoic and 3-methoxytetracosanoic acids) were detected in the conidia. Medium chain FA were predominant in HS treated conidia (64.65%) while long chain fatty acids constituted the major compounds in untreated conidia (62%). The long chain/medium chain FA ratio decreased from 1.8 in the conidia produced on untreated leaves to 0.5 in the conidia obtained from HS treated leaves. When comparing the sterol composition of Bgt conidia produced on leaves treated with HS versus conidia obtained from untreated ones, very important changes within the two major classes can be seen. In particular, 24-methylsterols, e.g., 24-methylenecholesterol and 24-methylcholesta-7,24-dien were reduced by about 82% whereas 24-ethylsterols, e.g., 24-ethylcholesterol and 24-ethylcholesta-5,22-dienol were increased by about 85%. The 24-methylsterols/24-ethylsterols ratio was reduced by ninefold in the conidia produced from HS treated leaves.  相似文献   

2.
Blumeria (=Erysiphe) graminis f.sp. tritici (Bgt), the causal agent of wheat powdery mildew, is responsible for an important disease leading to considerable yield reductions in wheat worldwide. Conidia of the obligate plant pathogen Bgt were analysed for their total fatty acid (FA) composition as a function of their ontogeny. A total of 17 FAs were detected (C(12)-C(24) saturated and unsaturated ones), including the presence of unusual long-chain monoenoic FAs. In young conidia, the major FAs were C(18:2) (23%), C(16:0) (16%), C(18:0) (15.2%) and C(18:1) (14.3%). In old conidia, the main FAs were C(24:1) (20.7%), C(22:0) (15%), C(22:1) (13.5%) and C(24:0) (9.7%). The amount of total FA was about 39 microg.mg of dry weight(-1) in young conidia and decreased clearly to 18 microg.mg of dry weight(-1) in older conidia. For the first time, we have demonstrated that the FA composition of conidia changes greatly with age. Medium-chain FAs (C(12)-C(18)) are predominant in very young conidia (75%), whereas long-chain FAs (C(22)-C(24)) are the major compounds in old conidia (74%). This study showed a significant elongation of FAs and a drastic decrease in the total FA amount during the ontogeny of conidia.  相似文献   

3.
比较了荧光素钠和考马斯亮蓝应用于小麦白粉病菌染色的效果。荧光素钠法中样品处理只需20min.左右,具有直接、快速的特点;荧光指示剂对病菌分生孢子萌发及菌丝生长无抑制作用,主要沉集于活菌体的隔膜和细胞质部位,使病菌产生明显的亮绿荧光和清晰的细胞轮廓,亮绿荧光衰退期为7min.;借助荧光显微镜可以观察病菌在小麦叶表的发展过程,区别活菌体和失活菌体。考马斯亮蓝法包括传统的组织学染色步骤,经过改进后的样品处理过程需要40min.左右;染色后使寄主组织呈现淡蓝色,病菌菌体染成深蓝色;该方法可以观察病菌在小麦叶表和被侵染细胞内部发育形成的结构,包括孢子发育形成的初生芽管、附着胞芽管、成熟附着胞以及在寄主细胞内形成的初生吸器原体、成熟的指状体吸器和次生吸器。  相似文献   

4.
Prophylactic efficacies of Iodus 40 and salicylic acid (SA) against wheat powdery mildew caused by Blumeria graminis f. sp. tritici have been shown and compared with those of heptanoyl salicylic acid (HSA) and trehalose. Plantlets treated once exhibited 55%, 50%, 95%, and 38% protection levels, respectively. Two sprayings increased these levels up to 60%, 65%, 100%, and 60%, respectively. Biological effects of these resistance inducers on reactive oxygen species (ROS) metabolism and lipid peroxidation were also investigated. We found clear differences in the extent and the type of induced responses, with HSA exhibiting both the most numerous and the highest effects. HSA and SA induced a 5.5-fold increase of whole cell DAB staining due to hydrogen peroxide accumulation, whereas Iodus 40 and trehalose increased staining intensity at the penetration sites only. However, these effects were not correlated with any modification of catalase (CAT), oxalate oxidase (OXO) or lipoxygenase (LOX) activities, except for HSA which decreased CAT in non-inoculated conditions and increased LOX in infectious conditions. HSA also induced an increase in the rate of lipid peroxidation, whereas Iodus 40 induced a decrease. The effects of the inducers on germinating conidia and wheat epidermal cells responding to fungal penetration were also investigated. Papilla-linked autofluorescence was affected by SA and Iodus 40 whereas germination was slightly altered by Iodus 40. The newly described protective efficacies and the partial, distinct and non-overlapping activities of these inducers on the wheat/powdery mildew interaction are discussed.  相似文献   

5.
The stem rust fungus Puccinia graminis f.sp. tritici is an obligately biotrophic pathogen attacking wheat (Triticum aestivum). In compatible host/pathogen-interactions, the fungus participates in the host's metabolism by establishing functional haustoria in the susceptible plant cells. In highly resistant wheat cultivars, fungal attack is stopped by a hypersensitive response of penetrated host cells. This mechanism of programmed cell death of single plant cells is accompanied by the intracellular accumulation of material with UV-fluorescence typical of phenolic compounds. A similar reaction can be induced in healthy wheat leaves by the application of a rust-derived elicitor. We analysed the biochemical composition of this defense-induced phenolic material. Contents of total soluble and cell wall esterified and etherified phenolic acids were determined in rust-inoculated and elicitor-treated leaves of the fully susceptible wheat cultivar Prelude and its highly resistant, near-isogenic line Prelude-Sr5. While no resistance-related changes occured in any of these fractions, the lignin content as determined by the thioglycolic acid and the acetyl bromide methods increased after elicitor treatment. Nitrobenzene oxidation revealed that the entire increase can be explained by an increase in syringyl units only. These biochemical data were confirmed by fluorescence emission spectra analyses which indicated a defense-induced enrichment of syringyl lignin for cell wall samples both from elicitor-treated wheat leaves and single host cells undergoing a hypersensitive response upon fungal penetration.  相似文献   

6.
Tissue-specific or regulated expression of transgenes is desirable in order to prevent pleiotropic side effects of putatively harmful transgene products as well as loss of energy resources due to unnecessary accumulation of transgene products. Epidermis-specific expression would be useful for many defense-related genes directed against attack by fungal pathogens that enter the plant body by direct penetration through the epidermis. In an approach to enhance resistance of wheat to the powdery mildew fungus Blumeria graminis f.sp. tritici, a novel epidermis-specific promoter was developed and used for expression of two defense-related genes. A 2.3 kb fragment of the wheat GstA1 promoter in combination with an intron-containing part of the wheat WIR1a gene was found to drive strong and constitutive transient expression in wheat epidermis. This promoter-intron combination was used for overexpression of oxalate oxidase 9f-2.8 and TaPERO peroxidase, two defense-related wheat genes expressed in inner leaf tissues. Expression studies of several transgenic lines by in situ oxalate-oxidase staining, RNA and protein blot analyses, as well as real-time PCR, demonstrated strong and constitutive transgene expression in the shoot epidermis. Transient as well as stable over-expression of the TaPERO peroxidase gene in wheat epidermis under the control of the GstA1i promoter resulted in enhanced resistance against Blumeria graminis f.sp. tritici, whereas oxalate-oxidase overexpression had no effect in either system. The data suggest that the wheat GstA1 promoter in combination with the WIR1a intron is useful for transgenic approaches to fungal disease resistance in cereals.  相似文献   

7.
8.
利用电镜技术对不同抗病性小麦品种上白粉菌吸器发育及相应寄主细胞变化的超微结构进行了研究,并对吸器的Ca2+-ATP酶活性及几丁质的分布进行了细胞化学定位分析。结果表明,小麦白粉菌(Blumeriagraminisf.sp.tritici)成熟吸器在内部结构上类似一个代谢活跃的菌丝细胞,有大量的线粒体和多聚核糖体;Ca2+-ATP酶主要被定位在寄主质膜及病菌核膜上;随吸器的不断发育,吸器外膜厚度增加,同时Ca2+-ATP酶活性增强。几丁质均匀地分布在吸器壁上,其含量随吸器的成熟而增加。在不同抗病性小麦品种上,吸器细胞核最先退化,然后是线粒体的液泡化和多聚核糖体的解聚。中抗寄主细胞内的吸器普遍退化较早,相当一部分在吸器中心体阶段已解体。此外,高感寄主表皮细胞与叶肉细胞之间有发达的胞间连丝;而且在吸器形成后,能比中抗寄主细胞更快地增殖和聚积大量与能量代谢、物质合成及分泌活动有关的细胞器。  相似文献   

9.
A study has been carried out to investigate the influence of nitrogen deficiency on intracellular lipid composition, including total fatty acid composition of lipids, polar lipids, and triacylglycerols, of the alga Botryococcus braunii Kütz IPPAS H-252 in batch culture. Under nitrogen limitation, the alga accumulates lipids as triacylglycerols and the total fatty acid (FA) composition changes: trienoic acids decrease (from 52.8–57.2 to 19.5–24.7% of the total FAs) and the oleic acid increases (from 1.1–1.2 to 17.1–24.4%) as does the saturated acids (from 23.7–26 to 32.9–46.1%). A similar rearrangement in the FA spectrum occurs at later times in the control culture, but it is less pronounced. Under nitrogen limitation, considerable changes in the polar lipid FAs are registered at day 13: saturated acids increase (from 28.6–35.5 to 76.8%) and all polyenoic acids markedly decrease (from 56.9–64.1 to 6.8%). Changes in the triacylglycerol fatty acid spectrum are seen on day 7: the oleic acid increases (from 14.7 to 34.2%) and remains at a high level till the end of the culture. In the control, triacylglycerols with large contents of oleic acid are detected at day 13, the total lipids and triacylglycerols still remaining unchanged.  相似文献   

10.
The fatty acid (FA) composition of Demospongiae species from the Sea of Okhotsk was studied. Fifteen sponge species were investigated for the first time, and the previously studied species Desmacella rosea and Myxilla incrustans were reexamined for their FA composition. Gas chromatography-mass spectrometry revealed 150 different fatty acids, of which 15 have not been identified in sponge lipids previously. The relative content of saturated FAs varied from 7.6 in Melonachora kobjakovae to 29.6% in Amphilectus digitata, with an average of 14.6% of total FAs. The relative content of monoenic FAs ranged from 12.8 in T. dirhaphis to 27.0% in Polymastia sp., with an average of 20.6% of total FAs. Non-methylen-interrupted, primarily unsaturated Δ5,9-FAs contributed a significantly to the amount of polyunsaturated fatty acids of sponges; this being a distinguishing feature of the FA composition of the investigated group of organisms.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号