稻瘟病菌激发子诱导非寄主植物的抗病效果

 Hyphal cell wall crude elicitor(CWE)of rice blast pathogen could induce hypersensitive response in tobacco and induce other nonhost plants to be resistant to other fungal pathogens.When corn was treated with CWE,they inhibited the infection of Exserohilum turcicum and Curvularia lunata,and when plants of capsicum and cucumber were treated with CWE,they inhibited the infection of Colletotrichum gloeospori-oides.CWE solution showed no bioactivity on spore germination and hyphal growth of the experiment fungi in vitro.Nonhost resistance induced by CWE to other fungal pathogens was not complete resistance.The induced resistant effect(IRE) increased as CWE concentration increased,however,IRE had somehow satura-ted concentration of CWE.Induced nonhost resistance by incompatible pathogen was quantitative to other compatible pathogens.The induced resistance was best at 2 or 3 d after CWE treatment,and then decreased.IRE was about 20 percent in 10 d after CWE treatment.     

Growth and physiological responses of Agriophyllum squarrosum to sand burial stress

Agriophyllum squarrosum is an annual desert plant widely distributed on mobile and semi-mobile dunes in all the sandy deserts of China. We studied the growth and physiological properties of A. squarrosum seedlings under different sand burial depths in 2010 and 2011 at Horqin Sandy Land, Inner Mongolia to understand the ability and mechanism that A. squarrosum withstands sand burial. The results showed that A. squarrosum had a strong ability to withstand sand burial. Its survival rate, plant height and biomass increased significantly at a burial depth 25% of seedling height and decreased significantly only when the burial depth exceeded the height of the seedlings; some plants still survived even if the burial depth reached 266% of a seedling height. The malondialdehyde(MDA) content and membrane permeability of the plant did not change significantly as long as the burial depth was not greater than the seedling height; lipid peroxidation increased and cell membranes were damaged if the burial depth was increased further. When subjected to sand burial stress, superoxide dismutase(SOD) and peroxidase(POD) activities and free proline content increased in the seedlings, while the catalase(CAT) activity and soluble sugar content decreased. Sand burial did not lead to water stress. Reductions in photosynthetic area and cell membrane damage caused by sand burial may be the major mechanisms increasing mortality and inhibiting growth of the seedling. But the increases in SOD and POD activities and proline content must play a certain role in reducing sand burial damage.     

稻曲病菌不同颜色厚垣孢子超微结构比较

 The surface and internal structure difference of yellow and black dormant chlamydospores of Ustilaginoidea virens on mid-and late-season rice were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM revealed that the spherical yellow and black chlamydospores had prominent spines, with the diameters from 3 to 6 μm and 4 to 6 μm, respectively. The spines were 200-700 nm and 400-1 100 nm long in yellow and black chlamydospores, respectively. Variance analysis showed that there was no difference in diameter of the yellow chlamydospores but significant difference among the black ones collected from both rice cropping types. Similarly, there was no difference in length of the spines on the same color chlamydospores but extremely different between the yellow and black chlamydospores collected from the two cropping types. TEM revealed that the cell wall of both color chlamydospores were composed of two layers, the thick endosporium and thin exosporium, and the thickness of the former layer of the black chlamydospores was nearly two times as that of the yellow ones. The organelles in yellow chlamydospores such as the nucleus were obviously visible, but invisible in black ones. The cytoplasm of black chlamydospores was occupied by a big lipid globule. This study suggests that the formation of dormant chlamydospores of U. virens is related with the structural changes in the cell.     

Evaluation of the efficiency of irrigation methods on the growth and survival of tree seedlings in an arid climate

Scarce and scattered precipitation in arid regions is detrimental for newly planted seedlings. It is essential to provide required water storage for seedlings in restoration projects in the first year of their establishment. The subsurface irrigation can be much more effective than the surface irrigation because of the regulation of water availability and reduction in water evaporation. We studied the effect of surface and subsurface irrigation methods on the growth and survival of four common tree species including heaven tree(Ailanthus altissima(Mill.) Swingle), China berry(Melia azedarach L.), white mulberry(Morus alba L.), and black locust(Robinia pseudoacacia L.) by installing underground clay reservoirs with different permeabilities in Isfahan City, Iran. Different amounts of animal manure and wheat straw were mixed with clay fraction and cooked in a pottery kiln at 900°C to produce reservoirs with different permeabilities. The experimental treatments consisting of irrigation and tree species were considered with a factorial arrangement in a completely randomized design with three replications in 2016 and 2017. Leaf water potential of seedlings, which is indirectly related to drought resistance, was measured by a portable pressure chamber. The results showed that saplings height, basal diameter, number of leaves, chlorophyll content and stomatal conductance were significantly(P0.05) higher in the subsurface irrigation with low permeability than in the surface irrigation, but the number of branches of the studied species were not significantly(P0.05) affected by the irrigation methods and different permeabilities of clay reservoirs. The clay reservoirs with low and medium permeabilities constantly provide better conditions for plant growth, and water with lower pressure and longer time intervals to the plant roots as compared with the reservoirs with high permeability. Analysis of variance of the data showed that year and interaction between year and permeability of reservoir had significant effects(P0.05) on all growth parameters, except for the chlorophyll content. In addition, the highest percentage of survival was 100% associated with the subsurface irrigation and the control treatment had the lowest survival percentages of 60%, 70%, 80% and 100% for M. alba, M. azedarach, A. altissima and R. pseudoacacia, respectively. Finally, the values of leaf water potential showed that R. pseudoacacia was the most drought resistant species.     

Effect of crude oil pollution on organic carbon and humus content in grey-brown soils in Mangyshlak, Pre-Caspian Sea Region

The organic carbon and humus content in oil polluted brown and grey-brown soils in Mangyshlak,Pre-Caspian Sea Region,was analyzed from 2000 to 2008.The results indicated that bitumen substances from crude oil pollution deteriorated the soil property,however,the organic carbon content increased significantly.The products of oil pollution changed the composition of car-bonaceous substances which formed soil humus,and changed the ratios of the humus components.Residual insoluble carbon increased with the rise of oil organic carbon.The mobility of humus components was significantly increased because of the high oxidation-reduction process in the topsoil,and the humus content and microorganism activity increased.The organic carbon content increased significantly,while it decreased with the distance away from the oil well.The rearrangement of physical,physical-chemical and chemical properties of the polluted soils was significant.     

西瓜感染黄瓜绿斑驳花叶病毒后糖的变化与倒瓤关系的研究

 By high performance liquid chromatography (HPLC), the contents of glucose, fructose and sucrose, and the sweetness were analyzed in watermelon inoculated with Cucumber green mottle mosaic virus (CGMMV).The relationship between sugar change and blood-flesh of watermelon was determined. The results indicated that the content of glucose was apparently increased compared to that of the control before maturity (within 28 days after pollination), but reduced to 24.8% of the control after maturity (at 35 days after pollination). The content of fructose was higher than that of the control within 14 days after pollination, and then decreased with a significant difference. In all cases, the content of sucrose increased with the growth of watermelon. However, compared with the control, the sucrose content of watermelon inoculated with CGMMV was lower. The ratios of glucose, fructose and sucrose in the total sugar were abnormal. Coincidence with the changes of the total sugar, the fruit sweetness before maturity was higher than that of the control, whereas decreased sharply after maturity (lower than that of the control). The inner pulp of the mature fruit appeared to be water-soaked and dirty red with no edibility. In a word, after inoculation with CGMMV, the changes of sugars and sweetness affected the watermelon quality.     

灰枣红点软腐病病原菌的鉴定

 The damage and symptoms of jujube fruit soft rot in Xinzheng, Henan Province, were investigated from 2006 to 2008, and the pathogen was identified based on the morphological characteristics and the ITS se-quence of ribosome DNA. The results showed that the aerial mycelium of colony was white in color in the first four days, then turned gray after incubation on PDA for 5-6 d at 25℃ and became black two weeks later. The mycelia grew luxuriantly with velvet character. The pycnidium was flask-shaped with a height of 196.9μm and a width of 213.3μm on the avereage. The conidium was colorless with single cell and had the shape of spindle, its size was (15.0-20.0)μm× (4.5-6.5)μm. The conidiophore was fastigiate. The homology of ITS sequence of ribosome DNA between the tested strain NXK and Botryosphaeria dothidea (GenBank ac-cession number:AJ938005) reached 99.87%, with a difference of only two base pairs. Based on the results of both morphological characters and molecular identification, the pathogen of jujube fruit soft rot in Xinzheng was identified as B. dothidea (Moug. ex Fr.) Ces. et de Not..     

Soil water and salt distribution under furrow irrigation of saline water with plastic mulch on ridge

Furrow irrigation when combined with plastic mulch on ridge is one of the current uppermost water-saving irrigation technologies for arid regions.The present paper studies the dynamics of soil water-salt transportation and its spatial distribution characteristics under irrigation with saline water in a maize field experiment.The mathematical relationships for soil salinity,irrigation amount and water salinity are also established to evaluate the contribution of the irrigation amount and the salinity of saline water to soil salt accumulation.The result showed that irrigation with water of high salinity could effectively increase soil water content,but the increment is limited comparing with the influence from irrigation amount.The soil water content in furrows was higher than that in ridges at the same soil layers,with increments of 12.87% and 13.70% for MMF9(the treatment with the highest water salinity and the largest amount of irrigation water) and MMF1(the treatment with the lowest water salinity and the least amount of irrigation water) on 27 June,respectively.The increment for MMF9 was gradually reduced while that for MMF1 increased along with growth stages,the values for 17 August being 2.40% and 19.92%,respectively.Soil water content in the ridge for MMF9 reduced gradually from the surface layer to deeper layers while the surface soil water content for MMF1 was smaller than the contents below 20 cm at the early growing stage.Soil salinities for the treatments with the same amount of irrigation water but different water salinity increased with the water salinity.When water salinity was 6.04 dS/m,the less water resulted in more salt accumulation in topsoil and less in deep layers.When water salinity was 2.89 dS/m,however,the less water resulted in less salt accumulation in topsoil and salinity remained basically stable in deep layers.The salt accumulation in the ridge surface was much smaller than that in the furrow bottom under this technology,which was quite different from traditional furrow irrigation.The soil salinities for MMF7,MMF8 and MMF9 in the ridge surface were 0.191,0.355 and 0.427 dS/m,respectively,whereas those in the furrow bottom were 0.316,0.521 and 0.631 dS/m,respectively.The result of correlation analysis indicated that compared with irrigation amount,the irrigation water salinity was still the main factor influencing soil salinity in furrow irrigation with plastic mulch on ridge.     

土壤处理对西洋参根际线虫数量动态的影响及对防治茎线虫根腐病的效果

 Root rot of American ginseng (Panax quinquefolium) caused by Ditylenchus destructor is a novel disease found recently in Beijing area. The effects of three soil treatments (fumigating with chloropicrin, chloropicrin + lvfeng organic manure and nematicide fosthiazate) on the number of rhizospheric nematodes, survived plants, root yield and root rot of 3-year ginseng plant were compared. The effects were also investigated at the second year after treatment. The results indicated that the number of parasitic nematodes in rhizosphere of treated soil reached the peak value in late June to early July as the soil temperature raised in the growing season. Compared with the regular treatment, the number of plant parasitic nematodes was reduced while non-plant parasitic nematodes increased. The number of non-plant parasitic nematodes in the soil treated with chloropicrin + lvfeng organic manure was 2 times than that treated with chloropicrin only. The ratio of non-parasitic to parasitic nematodes of three treatments was higher than the control. Percent of survived plants was 94.8%-96.4% and diseased root was decreased obviously. The control efficacy was more than 89% at the first year after treatment. The survived plants and plot yield of ginseng increased significantly and the control efficacy was around 40% at the second year. The best of the three treatments was by chloropicrin + organic manure.     

Variation in soil water content to rainfall under Caragana microphylla shrub in Horqin Sandy Land

In order to investigate the spatio-temporal variability of soil water content to rainfall under Caragana microphylla shrub in Horqin Sandy Land,a plot of 25 m × 25 m,where there were 6 shrub canopies of C. microphylla,was sited for measuring soil water content at two soil layers of 0-20 cm (top layer) and 20-40 cm (lower layer). Soil water content was measured on the 1st,5th,10th and 15th day after a 42 mm rainfall in Naiman of Inner Mongolia. The results showed that soil water contents at both layers under C. microphylla shrub were gradually decreased after the rain. Soil water content at the top layer outside the shrub canopy was higher than that inside the shrub canopy within 5 days,and became similar inside and outside the shrub canopy on the 10th day after the 42 mm rainfall,and it was lower outside than that inside the shrub canopy on the 15th day. The soil water content at lower layer in the area without shrubs was higher than that under shrub canopy all along. All the measured values of soil water content can be fitted to a variogram model. There was significant autocorrelation of the values of soil water content between top layer and lower layer,except for the fourth measured values of soil water content at top layer. The range and spatial dependence of soil water content at top layer were lower than that at lower layer.     

水稻基腐病菌毒素对烟草活性氧代谢及细胞超微结构的影响

 用水稻基腐病菌毒素注射烟草叶片后,烟草细胞中O₂^-_·和NO大量增加,H₂O₂含量明显降低,SOD、CAT和POD等酶的活性发生变化。毒素引起烟草细胞死亡,但没有细胞程序性死亡(PCD)的DNA梯特征。病菌毒素处理烟草叶片后,电导率增大,细胞膜透性增加。电镜观察烟草细胞的超微结构表明,毒素处理8h后,叶绿体变形,叶绿体基质片层大部分消解,基粒结构消失,叶绿体外膜和内膜剥离,质壁分离和细胞膜内陷,细胞器消解;处理48h后,细胞内含物完全消解,细胞膜消失,细胞壁皱缩变形。本研究表明,毒素引起烟草细胞死亡与植物抗病反应HR中细胞坏死的生理生化机制不同,但可能存在相似的信号传导途径。     

水杨酸对杂交稻抗白叶枯病的作用

杂交稻幼苗感染白叶枯病菌后,其叶片中苯丙氨酸解氨酶(PAL)活性明显提高,丙二醛(MDA)积累和膜透性显著增大,叶绿素含量与不饱和脂肪酸指数(IUFA)下降。经水杨酸(SA)预处理的植株PAL活性仍继续增加,而MDA含量和膜透性的增大趋势得到缓解,膜脂不饱和度增加。作者认为外源SA对杂交稻抗白叶枯病可能有多方面的作用。     

The effects of fluometuron on the ultrastructural development,chlorophyll accumulation and photosynthetic competence in developing velvetleaf seedlings

Velvetleaf (Abutilon theophrasti L.) seedlings were germinated in the presence of 0, 5, 10 or 80 μg/ml 1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea (fluometuron). The development of chloroplasts in the mesophyll tissue of the cotyledons was examined with the electron microscope and correlated with the accumulation of chlorophyll and the attainment of photosynthetic competence in 2- to 7-day-old seedlings. The formation of prolamellar bodies and their subsequent transformations into primary thylakoids were not prevented by fluometuron. However, membrane fusion into normal grana was altered by treatments containing this herbicide. Increasing the concentration of fluometuron reduced the number and length of stroma lamellae and promoted more elongate grana with fewer compartments. In addition to these structural changes, the seedlings treated with 5 μg/ml fluometuron accumulated only 50% of the chlorophyll that was present in the controls but remained green until necrosis developed. At 10 μg/ml, the seedlings exhibited a 75% reduction in chlorophyll content and became photobleached by the seventh day and treatment with 80 μg/ml resulted in only a trace of chlorophyll in the cotyledons and the albinistic appearance of seedlings. Net photosynthesis was completely inhibited by all treatments containing fluometuron. These observations indicate that in addition to being a Hill reaction inhibitor, fluometuron treatment directly alters the normal development of internal chloroplast membranes.     

光合细菌复配柠檬酸铜对移栽稻田水绵防效的研究

水绵是对水稻危害较重的低等藻类,本研究采用盆栽试验方法研究沼泽红假单胞菌复配柠檬酸铜对水绵的鲜重防效及施用后水绵中Mg²⁺、Fe²⁺、叶绿素含量和抗逆酶活性,同时测定了施用后水稻生长指标及抗逆酶活性。结果表明,施药后28 d,沼泽红假单胞菌复配柠檬酸铜对水绵的鲜重防效达92.17%,显著高于沼泽红假单胞菌或柠檬酸铜单独施用。与对照相比,水绵叶绿素、Mg²⁺和Fe²⁺含量分别显著降低60%,43%和39%,POD和SOD活性分别显著降低72%和71%,MDA含量显著升高50%。水稻叶片POD和SOD活性分别显著增加44%和104%,MDA含量显著降低51%,单株鲜重显著增加43%,分蘖数显著增加65%,株高增加5%。综上,沼泽红假单胞菌复配柠檬酸铜对水绵防效显著且对水稻安全,水绵叶绿素合成受到抑制和细胞膜过氧化作用是其对水绵防除的重要作用机理。     

木质部次生细胞壁增厚参与疣粒野生稻对黄单胞杆菌水稻变种的抗性

 黄单胞杆菌水稻变种（Xanthomonas oryzae pv.oryzae,Xoo）引起的水稻白叶枯病是一个世界性的严重病害。疣粒野生稻（Oryzae meyeriana）对Xoo具有高度抗性,但其抗性机制仍不清楚。本文以抗病的疣粒野生稻和感病的水稻品种大粒香为材料,研究了Xoo侵染对叶片病斑、叶绿体超微结构、光合系统活性和木质部超微结构的影响。结果表明,多种Xoo生理小种导致的疣粒野生稻叶片病斑长度都明显短于大粒香叶片的病斑长度。Xoo病菌侵染显著破坏了大粒香的叶绿体结构,明显抑制了其光合活性,而疣粒野生稻中的变化要轻得多。通过电镜切片,发现疣粒野生稻叶片导管内存在大量的Xoo病菌,这表明Xoo能够侵染疣粒野生稻且能够在叶片内增殖。病菌的侵染诱导了疣粒野生稻木质部次生细胞壁的增厚,抑制了病菌通过导管纹孔向邻近细胞的进一步侵染,这种反应可能参与了疣粒野生稻对Xoo的抗性。     

戊唑醇对小麦赤霉菌侵染影响的细胞学研究

采用电镜技术研究了三唑类杀菌剂戊唑醇(tebuconazole)对赤霉病菌Fusarium gramineaum侵染小麦穗部过程的影响.结果表明:人工接种前2天施药,可推迟外稃内表皮、内稃及子房上分生孢子的萌发,但不能完全抑制其萌发,可引起芽管和菌丝严重畸形,不能形成侵染菌丝侵入寄主.而人工接种后2天施药,戊唑醇则严重抑制了病菌菌丝的生长,使寄主体表和寄主组织内的菌丝形态、结构发生了一系列异常变化,并最终塌陷死亡,使菌丝不能扩展到穗轴部位.接种后4天施药,病菌虽已扩展到穗轴,但戊唑醇仍对穗轴中菌丝生长具有明显的抑制作用.对赤霉毒素的免疫细胞化学标记结果表明,药剂处理与未处理的寄主和菌丝细胞中都存在有毒素,但标记密度在药剂处理的寄主和菌丝细胞中明显低于未处理对照.     

马铃薯Y病毒侵染对叶绿体超微结构、光合和荧光参数的影响

 马铃薯Y病毒(PVY)侵染导致马铃薯叶片叶绿体个体变小,部分叶绿体的结构遭到破坏,淀粉粒的体积变小而粒数密度提高。随着病毒侵染,叶片中的叶绿素含量逐步减少,光合系统电子传递速率和净光合速率显著下降,而光系统Ⅱ的最大光化学效率则没有显著变化。PVY导致叶绿体结构破坏和碳同化酶活性下降,可能是造成光合作用下降的主要原因。     

Vuculic acid对空心莲子草叶片光合作用的影响

Vulculic acid(2-乙酰基-3,4-二羟基-5-甲氧苯基-乙酸)是从空心莲子草(Alternanthera philoxeroides)潜在生防真菌莲子草假隔链格孢(Nimbya alternantherae)培养滤液中分离获得的致病毒素.研究表明,该毒素为非寄主专化毒素,能够引致空心莲子草叶片细胞膜透性升高,导致电解质渗漏,同时降低叶片细胞内过氧化物酶(POD)和过氧化氢酶(CAT)的活性,使细胞防御酶系统发生紊乱,还能够造成空心莲子草叶片细胞质壁分离、质膜消解,叶绿体片层紊乱、膜消解[1,2].     

Effect of fluazifop-butyl on the chlorophyll content, fluorescence and chloroplast ultrastructure of Elymus repens (L.) Gould. leaves

Some aspects of the action of fluazifop-butyl on the chlorophyll content, chloroplast functioning and chloroplast ultrastructure of Elymus repens are reported. Over a period of 0–12 days after spraying with 0.25 or 1.0 kg ha^?1 of the herbicide, chlorophyll a and b contents of this susceptible plant decreased, progressing from the youngest to the more mature leaves. Newly formed tillers and the youngest expanding leaves exhibited a more severe type of chlorosis and were often found to be devoid of chlorophyll. A similar progressive decline of the chlorophyll content was observed in an experiment where leaf segments were floated in fluazifop-butyl. Evidence of a rapid and significant alteration of the normal chlorophyll fluorescence of E. repens leaves treated with fluazifopbutyl was obtained. The herbicide, at a concentration range of 0.25–1.0 μg μ1^?1, caused a significant loss of the fast fluorescence rise, fluorescence yield and, after 24 h, caused a total abolition of the fluorescence decay (PS decas). These results are discussed. Ultrastructural damage to chloroplasts was seen within 24 h after treatment with fluazifop-butyl. This damage ranged from a partial to total disruption of the outer chloroplast envelope and a disorganization of the internal thylakoid system. Such Ultrastructural effects on chloroplasts were found to intensify up to about 6–7 days after spraying, by which time nearly all chloroplasts in tissue sections were affected to some degree.     

土壤干旱下玉米幼苗解剖结构的伤害进程

石蜡切片和电镜观察发现,土壤中度干旱下,玉米叶片气孔密度增大,气孔的长、宽度明显减小;叶表皮细胞失水皱缩,"花环型结构"逐步被破坏;根皮层细胞体积变小,维管束杂乱分布;茎薄壁组织由排列整齐变为无序;叶肉细胞叶绿体在形状上膨胀麦圆,脂类小滴增多增大,叶绿体被膜逐渐膨散乃至断裂,叶绿体片层结构由排列整齐变为混乱,且间质片层对水分胁迫较敏感.