玉米大斑病菌孢子萌发和附着胞形成的影响因素研究

 Factors of influence on conidium germination and appressorium formation of Setosphaeria turcica,such as light condition,conidial concentration,nutrient resources and pH value of conidial suspension were studied.There was no significant difference among light treatments.The optimal pH for conidium germination and appressorium formation was 5.0 to 7.0.The exogenous nutrient sources were not the indispensable factors for conidium germination,but 5% sugar solution were more favorable for appressorium formation than the others.Low conidial concentration in suspension (conidia ≤ 10⁴/mL) was propitious to conidium germination and appressorium formation,which were inhibited significantly in higher concentration.It was suggested that the phenomenon was due to the self-inhibitor,a kind of lipophilic substance,existing in the site of conidium germination.     

蝴蝶兰软腐病中一种新致病菌的分离与鉴定

 Soft rot disease often affects Phalaenopsis amabilis during the growing season. However, the pathogen of the disease is remaining poorly studied. In this study, bacterial strain R1 was isolated from soft rot tissues in Wuhan. The pathogenic, morphological, physiological, biochemical tests and 16S rDNA sequence analysis were carried out. The homology of 16S rDNA sequence between strain R1 and Pseudomonas grimontii was 99.72%, and its physiological and biochemical properties were also similar to those of Pseudomonas grimontiis. All these evidences indicated that strain R1 could be identified as a novel strain of Pseudomonas grimontii. The pathogenicity of the novel isolate was proved according to the Koch's postulates. This is the first report that Pseudomonas grimontii can cause soft rot disease of Phalaenopsis amabilis.     

Tolerance to Zn deficiency and P-Zn interaction in wheat seedlings cultured in chelator-buffered solutions

Zinc deficiency is a common constraint for wheat production in the regions with limited precipitation,particularly in the regions with high levels of available phosphate (P) in soil.Two experiments were conducted using chelator-buffered nutrient solutions to characterize differences in tolerance to Zn deficiency among three winter wheat (Triticum aestivum L).genotypes and to investigate the relationship between P and Zn nutrition in wheat species.Four indices,Zn efficiency,relative shoot-to-root ratio,total Zn uptake in shoot,and shoot dry weight were used to compare the tolerance to Zn deficiency among three wheat genotypes.The results indicated that the four indices could be used in breeding selection for Zn uptake-efficient genotypes.The genotype H6712 was the most tolerant to Zn deficient,followed by M19,and then X13.Specifically,H6712 had the highest Zn uptake efficiency among the three genotypes.The addition of P to the growth medium increased Zn uptake and translocation from roots to shoots.Total Zn content of the wheat plant was 43% higher with 0.6 mmol/L P treatment than that of control with 0 mmol /L P treatment.The Zn translocation ratios from roots to shoots were increased by 16% and 26% with 0.6 mmol/L P treatment and 3 mmol/L P treatment,respectively,compared with 0 mmol/L P treatment.In contrast,high Zn concentrations in the growth medium inhibited P translocation from roots to shoots,but the inhibitive effects were not strong.Sixty-six percent of P taken up by wheat plants was translocated to the wheat shoots at 0 μmol/L Zn treatment,while the percent was 60% at 3 μmol/L Zn treatment.The result may be due to the fact that the wheat plants need more P than Zn.     

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.     

Dynamics of arbuscular mycorrhizal fungi associated with desert ephemeral plants in Gurbantunggut Desert

Previous studies documented that most desert plants can be colonized by arbuscular mycorrhizal (AM) fungi,however,little is known about how the dynamics of AM fungi are related to ephemerals in desert ecosystems.The dynamics of AM fungi with desert ephemerals were examined to determine the effects of host plant life stages on the development of AM fungi.Mean colonization of ephemeral annual plants was 45% lower than that of ephemeral perennial plants.The colonizations were much higher in the early part of the growing season than in later parts,peaking at flowering times.The phenology of AM fungi in root systems varied among different ephemerals.The density of AM fungal spores increased with the development of ephemeral annual plants,reached its maximum at flowering times,and then plateaued about 20 days after the aboveground senescence.A significant positive correlation was found between AM fungi spore density and biomass of ephemeral annual plants.The life cycles of AM fungi associated with desert ephemerals were very short,being about 60-70 days.Soil temperature and water content had no direct influence on the development of AM fungal spores.We concluded that the development of AM fungi was in response to desert ephemeral phenology and life history strategy.     

安徽桑黄花型萎缩病植原体16S rDNA序列分析及分子检测

 Mulberry yellow dwarf(MYD)disease is an quarantine disease and the causal agent is a phytoplasma.Two pairs of published universal primer, P1/P7 and Rm16F2/Rm16R1, based on the 16S-23S rDNA sequence of phytoplasma and total DNA extracted from infected mulberry tissues were employed for PCR and nested-PCR detection.The results revealed that a phytoplasma-specific 1 830 bp fragment with a G+C content of 46.01% was sequenced(GenBank accession No.GQ249410).The sequence shared 99.7% and 99.8% identity with aster yellows, the representatiive phytoplasma in 16SrI group, and mulberry dwarf phytoplasma classified into subgroup B in 16SrI group and named as the MYD phytoplasma strain Anhui(MYD-Anh).A phylogenetic tree based on 16S rDNA sequences was constructed and showed that MYD-Anh was clustered into 16SrI group.Identity of 16S rDNA sequence between MYD-Anh and mulberry yellow dwarf phytoplasma strain Zhenjiang(MD-zj) was nearly 100%, and they might belong to the same strain.Nested-PCR was used to detect the pathogenic phytoplasma from the differential tissues of mulberry infected with MYD-Anh.The results showed that a phytoplasma-specific 1.4 kb fragment was amplified with total DNA extracted from bark and vein.Nested-PCR was more sensitive than PCR for detecting MYD phytoplasma.     

苏云金芽孢杆菌晶体蛋白对北方根结线虫生物测定方法的建立和杀虫效果评价

 A bioassay procedure was developed to assess the toxicity of Bacillus thuringiensis crystal protein against Meloidogyne hapla,a root-knot nematode,under laboratory conditions.Reproducibility and precision of the bioassay results were optimal when forty 2nd stage juveniles were incubated in the dissolved crystal protein solution at 25℃,pH9.0 for 7 days.The juveniles were stained with 1% KMnO₄ for 2 hours or methylene blue solution for 1 hour to distinguish living and dead ones.By the bioassay procedure,the LC₅₀ value of strain YBT-1532 crystal protein against M.hapla was determined as 0.304±0.086 mg/mL(LC₅₀±1.96SE).Moreover,the strain YBT-1532 showed toxicity to Caenorhabditis elegans,a free-living nematode.All results indicated that YBT-1532 is a toxic strain to plant-parasitic nematode,and has the potential to control plant-parasitic nematode.     

The impact of land use change on soil organic carbon and labile organic carbon stocks in the Longzhong region of Loess Plateau

Land use change (LUC) is widely recognized as one of the most important driving forces of global carbon cycles. The soil organic carbon (SOC) and labile organic carbon (LOC) stores were investigated at arable land (AL), artificial grassland (AG), artificial woodland (AW), abandoned arable land (AAL) and desert steppe (DS) in the Longzhong region of the Loess Plateau in Northwest China. The results showed that conversions from DS to AL, AL to AG and AL to AAL led to an increase in SOC content, while the conversion from DS to AW led to a decline. The differences in SOC content were significant between DS and AW at the 20-40 cm depth and between AL and AG at the 0-10 cm depth. The SOC stock in DS at the 0-100 cm depth was 39.4 t/hm 2 , increased by 28.48% after cultivation and decreased by 19.12% after conversion to AW. The SOC stocks increased by 2.11% from AL to AG and 5.10% from AL to AAL. The LOC stocks changed by a larger magnitude than the SOC stocks, which suggests that it is a more sensitive index of carbon dynamics under a short-term LUC. The LOC stocks increased at 0-20 cm and 0-100 cm depths from DS to AW, which is opposite to that observed for SOC. The proportion of LOC to SOC ranged from 0.14 to 0.20 at the 0-20 cm depth for all the five land use types, indicating low SOC dynamics. The allocation proportion of LOC increased for four types of LUC conversion, and the change in magnitude was largest for DS to AW (40.91%). The afforestation, abandonment and forage planting on arable land led to sequestration of SOC; the carbon was lost initially after afforestation. However, the carbon sink effect after abandonment may not be sustainable in the study area.     

Quantifying the impacts of soil water stress on the winter wheat growth in an arid region, Xinjiang

Wheat growth in response to soil water deficit play an important role in yield stability. A field experiment was conducted for winter wheat (Triticum aestivum L.) during the period of 2002-2005 to evaluate the effects of limited irrigation on winter wheat growth. 80%, 70%, 60%, 50% and 40% of field capacity was applied at different stages of crop growth. Photosynthetic characteristics of winter wheat, such as photosynthesis rate, transpiration rate, stomatal conductance, photosynthetically active radiation, and soil water content, root and shoot dry mass accumulation were measured, and the root water uptake and water balance in different layer were calculated. Based on the theory of unsaturated dynamic, a one-dimensional numerical model was developed to simulate the effect of soil water movement on winter wheat growth using Hydrus-1 D. The soil water content of stratified soil in the experimental plot was calculated under deficit irrigation. The results showed that, in different growing periods, evapotranspiration, grain yield, biomass, root water up- take, water use efficiency, and photosynthetic characteristics depended on the controlled ranges of soil water content. Grain yield response to irrigation varied considerably due to differences in soil moisture contents and irrigation scheduling between seasons. Evapotranspiration was largest in the high soil moisture treatment, and so was the biomass, but this treatment did not produce the highest grain yield and root water uptake was relatively low. Maximum depth of root water uptake is from the upper 80 cm in soil profile in jointing stage and dropped rapidly upper 40 cm after heading stage, and the velocity of root water uptake in latter stage was less than that in middle stage. The effect of limited irrigation treatment on photosynthesis was complex owing to microclimate. But root water uptake increased linearly with harvest yield and improvement in the latter gave better root water uptake under limited irrigation conditions. Appropriately controlled soil wate     

麦麸中小麦矮腥黑穗病菌孢子的提取方法

 对麦麸中小麦矮腥黑穗病菌孢子的提取方法进行了研究。通过建立的"过筛-α-淀粉酶降解"、"过筛-密度梯度离心"和"过筛-α-淀粉酶降解-密度梯度离心"等方法能从麦麸中提取TCK孢子。提取的TCK孢子数量与网筛、α-淀粉酶和密度梯度离心的应用情况有关,而提取的TCK孢子纯度则主要与密度梯度离心有关。选用双层纱布和5种不同规格的网筛或网筛组合进行过筛能弃除83.88%~94.09%的麦麸,应用"过筛-α-淀粉酶降解"方法能弃除95.01%~99.00%的麦麸,并能提取19.2%~51.7%的TCK孢子。在"过筛-密度梯度离心"实验中,只有60目+200目+300目+30μm+11μm该网筛组合处理能获取7.2%的纯孢子,密度梯度离心对孢子的网嵴高度、自发荧光和萌发没有影响;在"过筛-α-淀粉酶降解-密度梯度离心"实验中,60目+200目+300目和60目+200目+300目+30μm+11μm这2组网筛处理可分别得到18.8%和12.2%的纯孢子,该处理对孢子网嵴高度没有影响。     

紫外线诱变莱氏绿僵菌对敌敌畏的耐药性

为筛选出对常用有机磷杀虫剂敌敌畏具有较强耐药性的莱氏绿僵菌Metarhizium rileyi突变菌株,本文通过紫外线照射诱变莱氏绿僵菌,并利用敌敌畏对紫外突变菌株进行4次药剂理化诱变,并对突变株进行了抗性水平、遗传稳定性测定,得出敌敌畏对莱氏绿僵菌孢子的致死浓度为1 291 mg/L,适合莱氏绿僵菌紫外线诱变的最佳照射时间为2 min和2.5 min,得到6株能耐1 291 mg/L敌敌畏的突变菌株,其中突变株Nr-UVY6的抗性水平是出发菌株的2.57倍,抗药性遗传稳定性也最佳。     

球孢白僵菌不同分离株的生物学特性的研究

为了明确不同白僵菌菌株的生物学特征,对15株白僵菌菌株的ITS片段进行测序分析,并对这些菌株的菌落生长速率、产孢量、孢子萌发率、单芽管孢子萌发比例、单芽管平均长度和长芽管平均长度等多项生物学指标进行测定。结果表明,单芽管孢子萌发比例变化范围在11．91％～96．03％;单芽管平均长度和双芽管平均长度分别为6．28-21．43μm和10．338～19．902μm;各菌株间孢子萌发率差异很大,变化范围22．09％-86．32％。对菌株的培养特性（孢子萌发率、产孢量和菌落生长速率）与孢子萌发特性（单芽管孢子萌发比例、芽管总平均长度和芽管整齐度）这两个主因子进行典型相关分析,两性状集团总体相关不显著（P=0．341）,而孢子萌发率与单芽管孢子萌发比例相关显著,菌落生长速率与芽管总平均长度呈显著相关。     

苏云金芽孢杆菌HBF-1芽孢对棉铃虫幼虫生长发育及酶活的影响

苏云金芽孢杆菌HBF-1菌株的芽孢对初孵棉铃虫幼虫无明显杀伤作用,但可以直接影响其正常的生长发育,使幼虫前期体重增加;而后期发育迟缓,历期延长,成虫产卵量明显减少。通过光学显微镜观察发现,用含有HBF-1芽孢的饲料饲喂棉铃虫幼虫,幼虫中肠肠壁细胞遭到破坏;随着虫龄的增大,微绒毛逐渐脱落,有的部位细胞壁破裂。酶活的测定结果表明:初孵棉铃虫幼虫取食含有HBF-1芽孢(100μg/g)的饲料后,幼虫体内的乙酰胆碱酯酶、羧酸酯酶和谷胱甘肽-S-转移酶的活性发生了变化。     

木霉耐盐突变菌株的紫外诱变选育

为了获得高效耐盐木霉突变菌株,以盐碱土中分离的一株深绿木霉T-YM作为原始菌株进行紫外诱变处理,并筛选了突变菌株的最佳诱变条件,利用NaCl溶液模拟盐胁迫条件测定了突变菌株耐盐指标生长速率、产孢量和菌丝生长量。结果表明,与对照(野生型菌株)相比,当诱变时间为3 min时能够显著提高深绿木霉T-YM突变菌株菌落生长速度和产孢量,分别增加17.69%和28.82%;诱变时间为0.5 min和5 min时能够显著提高突变菌株菌丝生长量,分别增加42.22%和46.67%。利用10 mg·mL^-1 NaCl溶液模拟盐胁迫条件时,与对照相比突变菌株菌落生长速度、产孢量和菌丝干重整体高于野生型菌株,尤其当诱变时间为3 min时,不同浓度盐胁迫下其产孢量平均增加51.18%,诱变时间为0.5 min时其菌丝干重平均增加23.65%;NaCl胁迫(10 mg·mL^-1)下,诱变处理0.5 min获得的正突变菌株经传代接种培养后其耐盐性较为稳定。因此,紫外诱变可作为一种选育高效耐盐木霉突变菌株的有效方法。     

粉红粘帚霉67-1菌株寄生核盘菌研究

 用诱捕法从海南乐东县菜园土壤中获得一株对核盘菌菌核具有强寄生能力的粉红粘帚霉(Gliocladium roseum)菌株67-1,寄生频率为100%。该菌的PDA平板回接核盘菌菌核,一周后寄生率可达100%。对峙培养发现其对核盘菌有明显的抑菌带。保湿条件下,该菌孢子在24h内成功侵入核盘菌菌核。切片显微观察证明该菌能高效侵染菌核,造成组织溃解。寄生过程中菌核内蛋白组成发生明显变化。这一菌株在22~35℃均能很好生长,菌丝及产孢最适温度为24℃,产孢量大。认为这一菌株具有良好的菌核病生防应用潜力。     

Germination of <Emphasis Type="Italic">Gibberella zeae</Emphasis> ascospores as affected by age of spores after discharge and environmental factors

The effects of age of ascospores (0–18 days after discharge), photon flux density (0–494 mol m^–2 s^–1 PAR), temperature (4–30 °C), frost (–15 °C for 30 min), relative humidity (RH; 0–100%), pH (2.5–6.5) and dryness (0 and 53% RH for up to 40 min) on the germination of the ascospores of the mycotoxin-producing fungus Gibberella zeae (anamorph Fusarium graminearum) were studied. Freshly discharged ascospores germinated within 4 h at 20 °C and 100% RH. The rate of germination and the percentage of viable ascospores decreased over time after the spores were discharged from perithecia. The time course of ascospore germination was not significantly affected by photon flux density. The period of time required to obtain 50% germinated ascospores at 100% RH was 26.90 h at 4 °C, 10.40 h at 14 °C, 3.44 h at 20 °C and 3.31 h at 30 °C. There was no significant effect of frost on the percentage of viable ascospores. A small percentage (6.6 ± 3.8%) of the ascospores germinated at 53% RH. At RH 84% and 20 °C almost 100% of the freshly discharged ascospores germinated. The time course of ascospore germination was affected by pH. The maximum rate of ascospore germination was estimated to be at pH 3.76. Ascospores lost their ability to germinate following exposure to 0% RH almost instantaneously. No germinating spores were detected after an incubation period of 1 min at 0% RH. Incubating the ascospores at 53% RH decreased the percentage of viable spores from 93 to 6% within 10 min. The data demonstrate that age of spores, relative humidity, temperature and pH, but not photon flux density, are key factors in germination of G. zeae ascospores.     

蔬菜田常用农药对诺氏虫疠霉生长和产孢的影响

研究了17种蔬菜田常用杀虫剂、杀菌剂对诺氏虫疠霉生长及产孢的影响。结果表明，在10种杀虫剂中，恶二嗪类杀虫剂安打对菌落生长和产孢的影响最小，抑菌率仅为15．78％，产孢量与对照无显著差异。新烟碱类杀虫剂吡虫啉对诺氏虫疠霉抑制作用最强，抑菌率达到100％。7种杀菌剂对诺氏虫疠霉生长和产孢影响都很显著，其中取代苯基类杀菌剂乙霉威对其影响最小，抑菌率为31．51％，但产孢量不到对照的1／3。有机硫类杀菌剂代森锰锌对诺氏虫疠霉生长、产孢的影响最大，抑菌率为100％。     

特基拉芽胞杆菌JN-369抗菌粗蛋白的理化性质和抑菌效果

特基拉芽胞杆菌Bacillus tequilensis JN-369是1株对稻瘟病菌Magnaporthe oryzae有较好拮抗作用的植物内生细菌,其发酵液经硫酸铵沉淀后得到抗菌粗蛋白。为明确菌株JN-369抗菌粗蛋白的抑菌机理,首先确定了该抗菌粗蛋白抑菌谱、热稳定性、酸碱稳定性、紫外稳定性以及酶稳定性,并观察研究了抗菌粗蛋白对稻瘟病菌菌丝和分生孢子的抑制作用。并采用针刺离体接种法测定了40%稻瘟灵EC、25%三环唑WP及不同浓度JN-369抗菌粗蛋白对水稻稻瘟病的拮抗效果。结果表明：菌株JN-369抗菌粗蛋白抑菌谱广,对葡萄灰霉病菌、草莓灰霉病菌和水稻稻瘟病菌等13种植物病原真菌及卵菌表现出抑制作用,而对油菜菌核病菌没有抑制作用;该粗蛋白理化性质相对稳定,具有应用于粮食作物生物防治的潜力;对稻瘟病菌的菌丝生长和分生孢子萌发有双重抑制作用,能使病原菌菌丝细胞膨大,并可抑制病菌分生孢子的萌发;离体防效试验显示,供试杀菌剂对水稻稻瘟病均有显著的拮抗效果,菌株JN-369抗菌粗蛋白在浓度为50～100 μg/mL时对稻瘟病的拮抗效果最好,该菌株有望开发为防治稻瘟病的生防菌株。     

短短芽胞杆菌Bb5911的复合诱变及其对香蕉炭疽病的防治作用

为了提高拮抗菌对香蕉炭疽病的抑菌活性并探讨其与化学药剂混用的可行性,本研究采用紫外线-亚硝酸钠复合诱变的方法对短短芽胞杆菌Bb5911进行诱变,并测试了其与咪鲜胺混配对香蕉炭疽病的防治效果。结果表明,最佳诱变条件为在距离20 W紫外灯50 cm下照射15 s,然后经300 mmol/L NaNO₂诱变处理60 min。经过2次复合诱变后得到突变株5B37-3的抑菌活性最强,比出发菌株提高了112.41%。咪鲜胺对突变株5B37-3的最低抑菌浓度（MIC）为20.83 μg/mL。连续转接7次,突变株5B37-3的抑菌活性无明显降低。抑菌谱测试结果表明,突变株5B37-3对13种植物病原真菌的抑菌活性比出发菌株均有提高,提高率18.20%~239.27%。对香蕉炭疽病防治的试验结果表明,突变株5B37-3的防效明显高于出发菌株,最高为66.55%。突变株5B37-3与10.42 μg/mL咪鲜胺溶液复配后,香蕉贮藏15 d,其防治效果为72.76%,与333.33 μg/mL咪鲜胺溶液防效相当;至香蕉贮藏17 d,其防治效果显著低于333.33 μg/mL咪鲜胺溶液。