Phytoplasma [Stolbur-subgroup (Bois Noir-BN)] infection inhibits photosynthetic pigments, ribulose-1,5-bisphosphate carboxylase and photosynthetic activities in field grown grapevine (Vitis vinifera L. cv. Chardonnay) leaves

In this work we have studied the influence of phytoplasma-induced grapevine yellows (yellowing) on some features of the thylakoids from field grown grapevine (Vitis vinifera L. cv. Chardonnay) leaves. Changes in photosynthetic pigments, soluble proteins, ribulose-1,5-bisphosphate carboxylase, photosynthetic activities and thylakoid membrane proteins were investigated. The level of total chlorophyll and carotenoids, on a unit fresh weight basis, showed a progressive decrease in phytoplasma infected leaves. Similar results were also observed for total soluble proteins and ribulose-1,5-bisphosphate carboxylase activity. When various photosynthetic activities were followed in isolated thylakoids, phytoplasma infection caused marked inhibition of whole chain and photosystem (PS) II activity. Smaller inhibition of PSI activity was observed even in severely infected leaves. The artificial exogenous electron donors, DPC and NH₂OH significantly restored the PSII activity in both mild and severely infected leaves. The same results were obtained when F_v/ F_m was evaluated by Chl fluorescence measurements. The marked loss of PS II activity in infected leaves was evidently due to the loss of 33, 28–25, 23, 17 and 10 kDa polypeptides. This conclusion was confirmed by immunological studies showing that the content of the 33 kDa protein of the water-splitting complex was diminished significantly in infected leaves. Phytoplasma infection induced a fast degradation of LHCP II which became visible as yellowish colour in leaves.     

一种镰刀菌对空心莲子草的致病力与寄主专一性测定

从罹病的空心莲子草上分离到一种镰刀菌,人工接种条件下,3叶期的空心莲子草幼苗最易发病,叶部次之.在供试的4个菌株中,以YZ-03菌株的致病力最强,该菌株接种空心莲子草幼苗5d后,接种的植株病情指数已达100,8d后幼苗全部枯死;人工接种叶片和茎秆9d后,叶片的病情指数达90.95,接种茎秆的病情指数达85.19.采用27科61种植物对该镰刀菌进行寄主专一性测定,结果表明,该镰刀菌能使莲子草严重发病,也能侵染藜的幼苗,对包括主要农作物在内的其他59种植物均无致病性.     

Effects of Infection by Mycosphaerella graminicola on Translocation of Fluquinconazole in Wheat Seedlings

ABSTRACT Translocation of (14)C-labeled fluquinconazole was measured using combustion analysis and radio thin-layer-chromatographic analysis in seedling wheat leaves uninfected and infected with Mycosphaerella graminicola. Two isolates were used with differing sensitivity to demethylation inhibitor fungicides. Fluquinconazole was translocated acropetally, but not basipetally. Fluquinconazole accumulated around infection sites within 6 days after treatment. Accumulation occurred before M. graminicola hyphae had colonized the host mesophyll further than one host cell around the invasion site. This suggested that the accumulation was caused by a host response to infection. Infrared gas analysis showed that rates of transpiration and stomatal conductance in inoculated leaves were significantly increased very soon after inoculation but net photosynthesis was decreased. The actual mechanism of fungicide accumulation was not determined.     

Fusion of sensor data for the detection and differentiation of plant diseases in cucumber

The development of plant diseases is associated with biophysical and biochemical changes in host plants. Various sensor methods have been used and assessed as alternative diagnostic tools under greenhouse conditions. Changes in photosynthetic activity, spectral reflectance and transpiration rate of diseased leaves, inoculated with Cucumber mosaic virus (CMV), Cucumber green mottle mosaic virus (CGMMV), and the powdery mildew fungus Sphaerotheca fuliginea were assessed by the use of non‐invasive sensors during disease development. Spatiotemporal changes in leaf temperature related to transpiration were visualized by digital infrared thermography. The maximum temperature difference within a leaf was an appropriate parameter to differentiate between healthy and diseased plants. The photosynthetic activity of healthy and diseased cucumber plants varied as measured by chlorophyll fluorescence and compared to the actual chlorophyll content. Hyperspectral imaging data were analysed using spectral vegetation indices. The results from this study confirm that each pathogen has a characteristic influence on the physiology and vitality of cucumber plants, which can be measured by a combination of non‐invasive sensors. Whereas thermography and chlorophyll fluorescence are unspecific indicators for plant diseases, hyperspectral imaging offers the potential for an identification of plant diseases. In a sensor data fusion approach, an early detection of each pathogen was possible by discriminant analysis. Although it still needs to be validated under real conditions, the combination of information from different sensors seems to be a promising tool.     

根施外源甜菜碱对胡杨幼苗叶片积累甜菜碱与耐盐特性的影响

在不同盐分处理下(0、100、200、300、500 mmol·L~(-1)Na Cl)对土壤进行盆栽实验,研究根施甜菜碱(GB,5 mmol·L~(-1))对1 a生胡杨(Populus euphratica)幼苗叶片甘氨酸甜菜碱(GB)积累特性与不同时间(第7天、第14天)光合作用的影响。结果表明:(1)盐胁迫单独处理下,相比对照(0 mmol·L~(-1)Na Cl,CK)叶片甜菜碱随盐胁迫强度增大积累量显著增多。盐胁迫和外源GB双重处理下,叶片GB含量总体趋势随盐浓度升高表现为先升高后保持平稳。在低盐胁迫处理时(100~300 mmol·L~(-1)Na Cl)外源GB能诱导叶片产生更多GB,较未经GB处理组叶片GB积累量分别提高44.0%、32.5%和35.9%,而高盐胁迫(500 mmol·L~(-1)Na Cl)则转为抑制,叶片GB含量降低了5.1%。(2)随着盐浓度升高,外源GB虽不能持续促进叶片GB含量,但其对光合维持能力却没有丧失。随着胁迫强度增加,外源GB对叶绿素含量、水分利用效率(WUE)、叶片相对含水量(RWC)及相关光合参数的维持作用越明显。(3)不同时间下盐分和外源GB对胡杨光合作用的影响会改变,外源GB先维持胡杨水分传递过程,后维持CO_2同化能力,最终提高其光合作用。总之,根施GB能够促使胡杨叶片GB积累量发生变化并发挥作用,调节盐胁迫下胡杨光合相关生理过程从而提高其耐盐能力。     

Peroxidase activity in rice leaves infected withHelminthosporium oryzae in relation to lesion maturation

Two-week-old seedlings of two rice varieties, resistant CH13 and susceptible Benibhog, were inoculated with a conidial suspension ofHelminthosporium oryzae. The resistant host exhibited greater peroxidase activity than the susceptible one when infected with the pathogen. Enzyme activities were measured 0, 24, 48, 72, 96 and 120 h after infection. Peroxidase activity in diseased leaves bearing young lesions,i.e., 24 h after inoculation, was not appreciably different from that in non-infected leaves. At the intermediate and mature stages of lesion development,ri.e., 72 and 120 h after inoculation, a marked increase in peroxidase activity was observed. The pattern of increased enzyme activity was similar in both varieties but the whole event proceeded faster in the resistant variety. No marked change in peroxidase activity in healthy leaves of both the varieties was noticed with increase of seedling age.     

Effect of foliar diseases of wheat on the physiological processes affecting yield under semi-arid conditions

The effects of Septoria leaf blotch (caused by Mycosphaerella graminicola) and leaf rust (caused by Puccinia recondita ) on the physiological processes affecting yield were studied under semi-arid conditions in Israel. In the absence of water stress, photosynthetic activity decreased as the rate of disease development increased. Transpirational activity was reduced in leaves infected by Septoria leaf blotch, but intensified in leaves with slight leaf rust infections (0.5-5% severity). When leaf rust seventy exceeded 5%, the transpirational water loss declined. Both diseases were associated with a decrease in the maximum rate of grain-weight accumulation, but did not affect the duration of weight accumulation. An inverse linear relationship between disease and final grain weight was observed. Under conditions of water stress, photosynthetic activity of leaves slightly infected by Septoria leaf blotch (1-5"., severity) was greater than that of uninfected leaves. Severely infected leaves (" 25% severity) photosynthesized the least. Both diseases were associated with a decrease in the maximum rate of grain weight accumulation, but the duration of accumulation was longer in tillers with a slow rate of disease development than in uninfected tillers. The relationship between disease and final grain weight in these cases was parabolic; yield was increased at low levels of infection. Theoretical explanations and practical implications of these phenomena are presented and discussed.     

黄瓜内生放线菌的分离、筛选及其活性菌株鉴定

 从植物内生放线菌中筛选拮抗活性菌株和寻找新的农用活性代谢产物,可为植物病害防治提供新的资源。本研究结果发现黄瓜幼苗的根、茎、叶中均有内生放线菌的存在,根组织中的数量、种类明显多于叶片和茎,占总分离株的72.7%,以链霉菌的淡紫灰类群、灰褐类群为主。活性筛选试验结果表明,黄瓜内生放线菌中对12种靶标真菌和6种细菌具有拮抗作用的菌株分别占46.8%和39.0%,主要为分离自根组织的链霉菌淡紫灰类群。分离自黄瓜叶片的gCLA4菌株抑菌谱较广,其发酵滤液对供试12种靶标真菌均具有较好的抑菌效果,但对靶标细菌有选择性抑制作用。形态学、细胞化学和16S rDNA序列分析鉴定该菌株为淡紫灰链霉菌(Streptomyces lavendularectus)。     

稀植栽培对旱地冬小麦光合特性、产量及水分利用效率的影响

为了探明稀植栽培对旱地冬小麦光合特性、产量及水分利用效率的影响,在大田试验条件下,测定分析了不同稀植条件下4个主茎和分蘖成穗并重型冬小麦品种旗叶的光合速率、光合量子产量、相对电子传递速率及群体透光特性、小麦籽粒产量和水分利用效率.结果表明,在从扬花到蜡熟期,稀植栽培可使小麦旗叶光合速率、光合量子产量、相对电子传递速率和群体透光率提高,各品种之间变化较为一致.播量为450万株/hm~2(传统高产栽培播量)处理比150万株/hm2播量处理旗叶的光合衰减率提高25.2～43.5个百分点,光合量子产量和相对电子传递速率分别降低2.95%～20.68%和10.66%～18.32%,群体上层的光截获量增加,中下部受光条件较差.表明稀植栽培下小麦生育后期在光合能力、电子传递和光能转化方面均具有明显优势.适当降低播量(300～375万株/hm~2),建立合理的群体结构,冬小麦籽粒产量和水分利用效率较播量为450万株/hm~2处理分别平均提高12.55%和14.48%,表明适当稀植栽培能显著提高冬小麦的产量和水分利用效率.     

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。     

丙烷脒对番茄植株生长、叶片光合作用和前期产量的影响

较系统地测试了新型烷基脒类内吸性杀菌剂丙烷脒对番茄Lycopersicon esculentum Mill.植株生长、叶片光合作用和前期产量的影响。结果表明:丙烷脒对番茄植株生长有明显的调控作用,且与使用剂量有关。在100.00 g/hm2有效剂量下,与空白对照相比,丙烷脒处理可增加番茄植株粗壮度(株高相对生长速率降低35.00%,茎粗净增长量增加151.96%);使番茄叶片光合色素Chl a、Chl a+b、Car含量分别增加22.02%、15.17%和13.04%,光合能力增强 (Pn提高21.80%,Gs增大42.31%,Tr增大53.72%,Ci减小9.58%);使番茄叶片厚度增加21.88%,但单位面积叶片质量减少13.95%;番茄前期产量较对照增加25.70%。表明丙烷脒在推荐剂量下可明显促进番茄的生长,并可显著提高其前期产量。     

Herbicidal potential of pyrenophorol isolated from a Drechslera avenae pathotype

A pathotype of Drechslera avenae (Eidam) Scharif exhibited host‐specificity, being pathogenic to Avena sterilis L but not to a number of related or unrelated species tested. In culture, the fungus produces a metabolite which was identified as the macrodiolide pyrenophorol (5,13‐dihydroxy‐8,16‐dimethyl‐1,9‐dioxa‐cyclohexadeca‐3,11‐diene‐2,10‐dione). This compound at a concentration of 320 µM was phytotoxic to A sterilis and considerably less so to Avena fatua L. The phytotoxicity was expressed as leaf necrosis on seedling cuttings partially immersed in pyrenophorol solution and as ‘green islands’ on detached leaves on which droplets of the solution were placed. Seed germination and seedling growth of A sterilis were not affected. Pyrenophorol at concentrations up to 640 µM did not cause any symptoms of phytotoxicity to a number of other monocotyledons or dicotyledons tested, with the exception of Lycopersicon esculentum Miller on which leaf necrosis was observed after application of the substance through the vascular system to seedling cuttings. These findings are discussed in relation to the exploitation of such compounds of natural origin as wild oat herbicides. © 2000 Society of Chemical Industry     

冠菌素对玉米苗期植株形态建成的调控效应

以玉米品种金海5号为材料,采用不同浓度植物生长调节剂冠菌素(COR)拌种和三叶期(V3)叶面喷施的方法,研究了COR对玉米苗期植株地上部和根系形态建成的影响,分析了其对叶面积、叶绿素含量和可溶性蛋白的调控效应。结果表明:不同浓度冠菌素对玉米幼苗形态建成的调控呈单峰曲线,即低浓度下促进幼苗生长,高浓度下抑制生长。用0.1 mg/L的COR拌种或叶面喷施处理,可促进玉米苗期植株株高和茎粗生长,增加单株叶面积,提高叶片叶绿素和可溶性蛋白含量,促进植株干物质积累。同时,COR可促进玉米苗期根系生长,增加根长和根表面积,进而可有效增加根系吸收能力。研究结果表明,适宜浓度的COR处理可以提高玉米幼苗光合性能,增强根系吸收能力,促进植株地上部和地下部的生长,有利于培育壮苗。     

沙芦内含物PAAC对干旱胁迫下玉米幼苗叶片光合及蛋白氧化损伤的保护作用

采用沙培试验,培养期间用沙丘芦苇特有的多氨基芳香族化合物PAAC水溶液对培养的两种不同基因型玉米幼苗叶片进行喷施处理,研究幼苗叶片在正常供水和干旱胁迫下的相对含水量、光合作用、叶绿素荧光等参数的变化趋势。确定这些生理指标在评价作物抗旱性方面的作用,并与甜菜碱溶液喷施处理的作物参比,研究该内含物对植物蛋白氧化损伤的影响。结果表明:PAAC溶液能够明显地降低干旱下植物叶片蛋白质中羰基含量的上升,即该内含物能够有效地减弱干旱胁迫下植物蛋白氧化损伤程度,RWC相对较高,说明PAAC一定程度上降低水分的散失。当植物受到中度干旱胁迫时,PAAC显著地减缓玉米叶片光合速率的下降,同时Fv/Fm、qP、ETR等叶绿素荧光参数数值也明显高于同期的对照,表明PAAC具有保护类囊体膜上PSⅡ的光合学活性的作用,一定程度上增强了植物的抗旱能力。     

枯斑盘多毛孢Pf-毒素活性组分的分离纯化

 对枯斑盘多毛孢(Pestalotia funerea)培养滤液用70%乙醇沉淀,将其分为可溶性和不可溶(蛋白质等大分子)组分,浸渍法活性检测表明,蛋白质等大分子物质对马尾松、湿地松切根幼苗没有致病活力,非蛋白部分(Pf-毒素)则保留了病原菌培养滤液的致病活性,且与病原菌培养滤液相比活性有所增强。以最适流动相,正丁醇:甲醇:水(4:1:2)为洗脱液,采用硅胶H60型柱反复柱层析,从枯斑盘多毛孢的甲醇粗提物质中分离出9种组分,经致病活性测定出3种组分,Rf值分别为0.83、0.79、0.80,它们对马尾松切根幼苗、湿地松切根幼苗针叶都有致萎作用。     

东北地区番茄细菌性溃疡病的发生和病原鉴定研究

 1988~1989年从北京市、辽宁和黑龙江省等地调查采集的患溃疡病的病株和病果上分离到17个细菌菌株,接种番茄幼苗、果实及叶片,均能产生典型的溃疡病症状,各菌株致病力无明显差异。各菌株经细菌染色反应,形态特征,培养性状,生理生化反应,血清学反应(ELISA法)及蛋白质凝聚丙烯酰胺胶电泳等鉴定,认为番茄溃疡病的病原细菌是:密执安棒杆菌密执安亚种(Clavibacter michiganense subsp.michiganense (Smith) Davies et al.)。试验表明病原细菌可经种子带菌传染,病残体和病土壤可能是初侵染菌源。抗病性测定45个番茄品种均属感病品种。寄主范围除番茄外,尚能侵染茄子、龙葵和心叶烟。     

Effect of phytoplasmal infection on photosystem II efficiency and thylakoid membrane protein changes in field grown apple (Malus pumila) leaves

We have studied the effect of the apple proliferation phytoplasmal infection on some features of the thylakoids from field grown apple (Malus pumila) leaves. Changes in photosynthetic pigments, soluble proteins, ribulose-1,5-bisphosphate carboxylase, nitrate reductase, photosynthetic activities and thylakoid membrane proteins were investigated. The level of total chlorophyll and carotenoids were reduced in phytoplasma-infected leaves. Similar results were also observed for soluble proteins and ribulose- 1,5-bisphosphate carboxylase activity. The in vivo nitrate reductase activity was significantly reduced in infected leaves. When various photosynthetic activities were followed in isolated thylakoids, phytoplasmal infection caused marked inhibition of whole chain and photosystem II activity while the inhibition of photosystem I activity was only marginal. The artificial exogenous electron donors, diphenyl carbazide and hydroxylamine significantly restored the loss of photosystem II activity in infected leaves. The same results were obtained when F_v/F_m was evaluated by chlorophyll fluorescence measurements. The marked loss of photosystem II activity in infected leaves could be due to the loss of 47, 33, 28–25, 23 and 17 kDa polypeptides. It is concluded that phytoplasmal infection inactivates the donor side of photosystem II. This conclusion was confirmed by immunological studies showing that the content of the 33 kDa protein of the water-splitting complex was diminished significantly in infected leaves.     

感染“中四”小麦条锈菌T4新菌系的寄生适合度研究

 为预测T4新菌系在我国未来小麦条锈菌的流行趋势,本研究以高感品种铭贤169为试材,以我国条锈菌5个主要流行小种（菌系）CYR29、CYR31、CYR32、CYR33、Su11-4为对照,采用主成分分析法测定了T4新菌系的寄生适合度。结果表明：在供试菌系范围内,决定其寄生适合度属性的3个主成分依次为条锈菌的侵染能力、扩展能力和产孢能力(繁殖力);通过建立数学模型计算供试菌系的侵染能力、扩展能力和产孢能力,结果表明：CYR33和CYR32相对寄生适合度较高,Su11-4的寄生适合度居中,CYR31及CYR29其寄生适合度较低,而感染“中四”苗期的新菌系T4,相对寄生适合度最低。结合该菌系对我国目前推广品种和后备品种致病性和毒性结果分析,该菌系在今后一段时间内不会成为我国小麦条锈菌的优势菌系。     

生物刺激素协同对草莓炭疽病防治及其生长发育的影响

草莓炭疽病是草莓定植时期最易造成死苗的真菌病害。本文研究了生物刺激素（木霉菌、海藻酸、聚谷氨酸）协同灌根对草莓炭疽病的防治以及促生作用。结果表明,与对照相比,木霉菌、海藻酸、聚谷氨酸单剂灌根和木霉菌+海藻酸、木霉菌+聚谷氨酸的协同灌根处理均能显著降低炭疽病造成的死苗率,其中木霉菌+海藻酸的防效最高,可达78.26%。相比对照,所有处理均能显著提高净光合速率、1,5-二磷酸核酮糖羧化酶活性和加氧酶活性等光合指标,以及土壤脲酶活性。协同灌根处理显著提高草莓株高、根茎粗、叶柄长、叶面积等生长指标达15.62%～47.00%。其中木霉菌+海藻酸处理的净光合速率、土壤脲酶活性最高。综合而言,木霉菌与海藻酸协同灌根在促进生长、促进光合、提高土壤供氮水平以及防控草莓炭疽病方面均表现出显著的增效作用,可作为生物防治的一种有效手段。     

Physiological response of yellow vein mosaic virus-infected bhendi [Abelmoschus esculentus] leaves

The effect of okra yellow vein mosaic virus infection on PS II efficiency and thylakoid membrane protein changes in field-grown bhendi (Abelmoschus esculentus) leaves was studied. The degree of virus infection was determined by means of the ratio of variable to maximum chlorophyll fluorescence (F_v/F_m). Changes in photosynthetic pigments, soluble proteins, nitrate reductase, photosynthetic activities and thylakoid membrane proteins were investigated. Okra yellow vein mosaic virus infection resulted in the reduction of photosynthetic pigments, soluble proteins, ribulose-1, 5-bisphosphate carboxylase activity and nitrate reductase activity. Virus infection caused marked inhibition of PS II activity. The artificial electron donors, diphenyl carbazide and hydroxylamine significantly restored the loss of PS II activity in infected leaves. The marked loss of PS II activity in infected leaves may be due to the loss of 47, 33, 28–25, 17 and 15 kDa polypeptides. It is concluded that the yellow vein mosaic virus infection inactivates the donor side of PS II.