Identification of disease resistances in wheat-<Emphasis Type="Italic">Leymus multicaulis</Emphasis> derivatives and characterization of <Emphasis Type="Italic">L. multicaulis</Emphasis> chromatin using microsatellite DNA markers

To identify resistance to Fusarium head blight (FHB), cereal yellow dwarf virus (CYDV), stem rust (Sr), and powdery mildew (Pm) in 24 common wheat (Triticum aestivum)-Leymus multicaulis addition/translocation lines that were developed cytogenetically and to verify the authenticity of these lines using microsatellite (SSR) DNA markers. Resistance to FHB was identified in the wheat-L. multicaulis addition lines, Line 9 and Line 26, which both contained L. multicaulis-specific fragments as shown by SSR markers. The translocation line, Trans 1, and the addition lines, Line 5 and Line 29, have resistance to stem rust (IT 0). Resistance to CYDV was evaluated based on virus titers measured by enzyme linked immunosorbent assay (ELISA). The addition line, Line 23, showed low virus titer (0.15), indicating resistance to CYDV. The segregation distribution of CYDV resistance in 98 F₂ plants of Line 23/CS showed a significant deviation from 3:1. Inoculation with a set of 14 differential Blumeria graminis f. sp. tritici (Bgt) isolates did not detect powdery mildew resistance in translocation line Trans 1, addition line Line 9 and the amphiploid of wheat-L. multicaulis. However, Line 26 exhibited the resistance response pattern of Kavkaz, which carries Pm8, indicating that Line 26 most likely has the powdery mildew resistance gene Pm8 inherited from its parent lines Feng Kang 7 or Feng Kang 10. Twelve SSR markers, distributed on different homeologous chromosome groups of wheat, which distinguished L. multicaulis addition/translocation chromosomes, were used to verify the presence of L. multicaulis chromatin in the putative wheat-L. multicaulis addition/translocation lines. Of the 24 addition/translocation lines investigated using the 12 polymorphic SSR markers, 18 wheat-L. multicaulis derivatives showed the expected L. multicaulis-specific fragments, indicating that all of these 18 addition/translocation lines would most likely have the introgressed L. multicaulis chromosome(s). Chromosomal rearrangements also were detected in some of the wheat-L. multicaulis introgression lines.     

Likely threat of the spread of race UG99 of <Emphasis Type="Italic">Puccinia graminis</Emphasis> f. sp. <Emphasis Type="Italic">tritici</Emphasis> on wheat in southeastern Russia

In 2013 and 2014, a Ug99 race virulent to the resistance gene Sr31 was revealed on spring bread wheat fields in Saratov oblast and its inoculum was collected under conditions of stem rust epiphytoties (with the fungus Puccinia graminis f. sp. tritici acting as an agent). In March to April 2015, when a set of soft wheat lines was artificially inoculated in a climatic chamber, the virulence of the collected inoculum to gene Sr31 was confirmed, and four monopustular clones were isolated. Based on the isolated monopustular clones of Puccinia graminis f. sp. tritici, an assessment for resistance of four lines of spring soft wheat to novel Sr-gene combinations was made.     

Susceptibility of G-genome tetraploid species of the genus <Emphasis Type="Italic">Triticum</Emphasis> L. to powdery mildew

According to the literature data, G-genome tetraploid species Triticum timopheevii and T. araraticum are highly resistant (immune) to powdery mildew. Unde-epephytoty of the disease, not a single pustule was found on the leaves of any T. timopheevii accessions or on most of the T. araraticum accessions. Infection of the spikes of accessions of the given species by this disease was found for the first time.     

Expression analysis of <Emphasis Type="Italic">RUS1</Emphasis> and construction of <Emphasis Type="Italic">RUS1</Emphasis> plant expressing vector

RUS1 was one of the disease resistance gene analogs obtained from Setaria italica Beauv. Semi-quantitative RT-PCR analysis result showed that RUS1 gene could be induced by Uromyces setariae-italicae and had relation to the resistance response of Setaria italica Beauv. against Uromyces setariae-italicae infection. Promoter sequence of RUS1 was obtained by the method of Genome Walking, and its length was 675 bp. RUS1 promoter and pCAMBIA1300 vector were fused to construct RUS1::GUS vector. GUS histochemical staining result showed that promoter could activate gene expression. RUS1 gene (including the promoter sequence) was obtained through PCR amplification and then fused with pCAMBIA1300 vector to construct pCAMBIA1300:RUS1 plant expressing vector. The research laid a foundation for gene functional identification of RUS1.     

Screening and identification of antagonistic <Emphasis Type="Italic">Streptomyces</Emphasis> spp. against <Emphasis Type="Italic">Clavibacter michiganensis</Emphasis> subsp. <Emphasis Type="Italic">michiganensis</Emphasis> from tomato rhizosphere

The objectives of our present study were to isolate antagonistic Streptomyces from tomato rhizosphere, and evaluate the potential strain for the biological control of bacterial canker of tomato. One hundred and seventy strains of isolated from tomato rhizosphere were tested for antibiosis activity against Clavibacter michiganensis subsp. michiganensis on double-layer agar. Sixty-three isolates showed antibiosis activity with diameter of an inhibition zone ranging from 1.0–6.5 cm. Fifteen Streptomyces strains had strong antibiosis activity against C. m. subsp. michiganensis with diameter of the inhibition zone above 4.0 cm on double-layer agar. Especially, the strain named Z-L-22 showed the strongest antibiosis activity with 6.5 cm inhibition zone. The fermentation filtrate also showed a high inhibition activity against Gram-positive bacteria such as Streptomyces scabies, Staphylococcus aureus, and Bacillus subtilis. Morphological, physiological and biochemical tests combined with 16S rDNA sequence analysis were carried out to identify the strain Z-L-22. Characteristics of the Z-L-22 were similar to those of Streptomyces setonii, and the 16S rDNA sequence showed 99.4% homology to S. setonii. Based on the polyphase taxonomic views, the Z-L-22 was identified as S. setonii.     

Activity of the photosynthetic apparatus and antioxidant enzymes in leaves of transgenic <Emphasis Type="Italic">Solanum lycopersicum</Emphasis> and <Emphasis Type="Italic">Nicotiana tabacum</Emphasis> plants,with <Emphasis Type="Italic">FeSOD1</Emphasis> gene

Introduction of the FeSOD gene enhanced the stability of the photosynthetic apparatus of plants to the action of oxidative stress caused by UV irradiation. The expression of Arabidopsis thaliana FeSOD gene, targeting the enzyme in chloroplasts due to a signal sequence, leaded to significant changes in ultrastructure of cell subcompartments of tobacco and tomato leaves. The activity of superoxide dismutase in leaves of transgenic tomato plants exceeded the value of activity of this enzyme of control plants. Transgenic tobacco plants showed increasing in SOD activity compared with control non-transgenic tobacco. The activity of AP in the leaves of transgenic tobacco and tomato plants was similar with that of control non-transgenic plants, but activity of one accession of transgenic tomato, which is also characterized by high values of SOD activity, exceeded the value of control plant. Differences in ultrastructural organization of chloroplasts in the cells of transgenic and control tobacco and tomato plants have been manifested in a strong enlargement in the size of plastoglobuli. These distinctions were evident especially in the cells of the leaf parenchyma of transgenic tomato as well as transgenic tobacco. Also, a quantity of starch grains in the plastids of guard cells was increased. Chloroplasts in the cells of leaf parenchyma in transgenic plants contained less a starch grains than in wild-type plants.     

Identification of <Emphasis Type="Italic">Lr24</Emphasis> with targeted region amplified polymorphism (TRAP) analysis in wheat

This research is aimed at developing TRAP markers, as a probe for library screening, closely linked to or co-segregated with Lr24. Ninety TRAP primer pairs were used to test the resistant and susceptible parents, as well as the resistant bulk and the susceptible bulk in our study. The polymorphic TRAP primers of TcLr24 were employed to genotype the F₂ population from TcLr24×Thatcher subsequently. Ten of 90 TRAP primer pairs displayed polymorphism between TcLr24 and Thatcher, accounting for 11.11%. A further study found that primer ARBI1/RGA-2F generated a 161 bp fragment presented only in the resistance plants of F₂ population. Forty-five other wheat leaf rust resistant NILs and 30 diploid materials of wheat were also tested to detect the specificity of the primer. This specific band was amplified in TcLr19, TcLr29, TcLr38, TcLr42 and TcLr44, but absented in all the 30 diploid materials. It was concluded that this marker ARBI1/RGA-2F was closely linked to Lr24, which could be used to detect Lr24 in the F₂ population of TcLr24×Thatcher, and be further used as a probe for cDNA and BAC library screening of TcLr24.     

Effects of salicylic acid on the behavior of Yali pear infected by <Emphasis Type="Italic">Alternaria kikuchiana</Emphasis> Tanaka

To investigate the inductive effect of salicylic acid (SA) on the resistance of Pyrus bretschneider cv Yali to black spot disease (Alternaria kikuchiana Tanaka), the physiological and biochemical characteristics of detached pear leaves at the age of 5 to 10 days were measured after application of SA. The results showed that exogenous SA significantly improved the resistance of Yali pear (Pyrus bretschneider cv Yali) leaves to black spot disease. For the SA treatment at 0.02 mmol·L⁻¹ SA concentration, the disease index was the lowest, and the induced resistance reached up to 63.9%. Furthermore, SA induced local and systemic resistance of Yali pear against the black spot disease. Expression of systemic resistance in leaves was detectable 3 d after SA treatments and lasted for 10 d. POD, PPO, and PAL activities of Yali pear leaves increased by SA treatment. It is suggested that exogenous SA solution as a chemical activator could induce the resistance of Yali pear to black spot disease.     

Allelopathic effects of <Emphasis Type="Italic">Thymus kotschyanus</Emphasis> on seed germination and initial growth of <Emphasis Type="Italic">Bromus tomentellus</Emphasis> and <Emphasis Type="Italic">Trifolium repens</Emphasis>

The allelopathic influence of aqueous extracts of Thymus kotschyanus on Bromus tomentellus and Trifolium repens germination (%), germination speed, and seedling growth (length, fresh and dry weight) was examined. It was noted that aqueous extracts had a considerable inhibitory effect on target plant germination, and the effect at 50%, 75%, and 100% concentration was found to be significantly higher than that at lower concentrations (5% and 25%) and control treatment (distilled water). Seedling length in addition to fresh and dry weights was also reduced significantly over control. The inhibitory effect was increased as the extract concentration was increased. B. tomentellus showed a higher sensitivity against T. kotschyanus in allelopathic effects compared to T. repens, which indicates that B. tomentellus planted in rangelands with leaf litter of T. kotschyanus will be adversely affected in terms of its germination, growth, and ultimately low forage production.     

Increase of resistance of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> plants to phytopathogenic fungi expressing hevein-like peptides from weed plant <Emphasis Type="Italic">Stellaria media</Emphasis>

It is shown that constitutive hyperexpression of new hevein-like peptides from the weed plant chickweed (Stellaria media)in mouse-ear cress (Arabidopsis thaliana) plants leads to a substantial increase of their resistance to phytopathogenic fungi Botrytis cinerea and Bipolaris sorokiniana. Thus, common chickweed peptides can play a definite role in protecting this weed plant and be useful as a new genetic tool for producing plants resistant to fungal diseases.     

The EST Analysis of A Suppressive Subtraction cDNA Library of Chinese Wild Vitis pseudoreticulata Inoculated with Uncinula necator

Uncinula necator is a worldwide serious fungus disease causing annual heavy lost on grapevine production. In order to get more informations on defense related EST sequences and help breeding program, we constructed and characterized a suppression subtractive hybridization cDNA library with artificially inoculated leaves and control Chinese wild Vitis pseudoreticulata clone Baihe-35-1, which is highly resistant to powdery mildew. In the library, the length of 58 EST fragments known as putative functions varied from 130 to 800 bp, and 60% of the ESTs exhibited high similarity to known sequences in database of GenBank with BLASTX analysis. These genes were involved in stress/defense response, detoxification, signal transduction, disease defense, and etc., and 14 ESTs remained unknown or hypothetical proteins, which may be new genes. The experiment provided an important basis for studying the disease-resistance mechanism and obtaining the genes for the aim of improving grapevine powdery mildew resistance.     

小麦抗白粉病种质“N9134”的抗性遗传分析

抗性种质"N9134"含有野生二粒小麦(资源编号:AS846)的抗白粉病基因。为了研究其白粉病抗性基因的遗传规律,用感病品种阿勃、中国春、陕160、陕优225与该种质正反交,结果F1白粉病感染0～1级,F2白粉病抗感比例为3∶1;以小麦缺体系与其杂交,F1白粉病感染0～1级,F2白粉病抗感比例除"5B"偏离3∶1外,其余均为3∶1。表明N9134的白粉病抗性由1对完全显性基因控制,位于"5B"染色体上。     

Use of molecular markers of potato golden nematode resistance genes <Emphasis Type="Italic">H1</Emphasis> and <Emphasis Type="Italic">GRO1</Emphasis>

By means of DNA markers of potato golden nematode resistance genes H1 and Gro1, 109 Russian- and foreign-bred potato varieties are assessed. A sufficiently high level of coincidence of the presence of marker alleles with phenotypic resistance of potato varieties is revealed. However, not all resistant forms have specific amplification products. The use of DNA markers of only two genes H1 and Gro1 will not make it possible to completely replace mass laboratory testing, but it will make it possible to select potato forms resistant to this parasite by a simple and reliable method in a shorter time and thereby to considerably reduce the number of genotypes in the sample for further breeding.     

Antibiogram and heavy metal resistance of pathogenic bacteria isolated from moribund cage cultured silver catfish (<Emphasis Type="Italic">Pangasius sutchi</Emphasis>) and red hybrid tilapia (<Emphasis Type="Italic">Tilapia</Emphasis> sp.)

Antibiogram and heavy metal resistance patterns of pathogenic bacteria isolated from moribund cage cultured silver catfish (Pangasius sutchi) and red hybrid tilapia (Tilapia sp.) from Sungai Manir, Terengganu, Malaysia were studied and characterized. Sungai Manir is one of the famous rivers in Terengganu for its wide variety of cage cultured freshwater fish. However, to date, the baseline information of antibiogram and heavy metal resistance patterns of the pathogenic bacteria attacking the freshwater fish cultured in Sungai Manir is still lacking. Therefore, this study was carried out, which may be useful for fish farmers as a guideline for fish prophylactic and treatment purposes. Furthermore, present studies also provide information on the safety level of consuming freshwater fish produced from Sungai Manir. In the present study, bacteria were isolated from 100 fish of each moribund silver catfish and red hybrid tilapia using seven media including tryptic soy agar (TSA), Mac Conkey, thiosulphate citrate bile salt (TCBS), eosin methylene blue (EMB), glutamate starch pseudomonas (GSP), xylose lysine deoxycholate (XLD) and Baird Parker media. Identification of bacteria was carried out using conventional biochemical tests and confirmed by commercial bacterial identification kit. Antibiogram of the bacterial isolates against 18 antibiotics; oxolinic acid (2 μg), ampicillin (10 μg), erythromycin (15 μg), furazolidone (15 μg), lincomycin (15 μg), oleandomycin (15 μg), amoxicillin (25 μg), colistin sulphate (25 μg), sulphamethoxazole (25 μg), chloramphenicol (30 μg), doxycycline (30 μg), florfenicol (30 μg), flumequine (30 μg), kanamycin (30 μg), nalidixic acid (30 μg), tetracycline (30 μg), nitrofurantoin (50 μg) and spiramycin (100 μg) was carried out using disk diffusion method, whereas heavy metal resistance patterns (Hg²⁺, Cd²⁺, Cr^{6 +} and Cu²⁺) of the bacterial isolates was determined through twofold agar dilution method. The results showed that the percentage of sensitivity case of the 120 bacterial isolates to the tested antibiotics was 62.7%. This was followed by resistance (26.9%) and intermediary sensitive (10.4%) cases. In terms of the heavy metal resistance patterns, all bacterial isolates were resistant to Hg²⁺ and Cr^{6 +}. However, only 27.8% and 16.7% of the bacterial isolates were sensitive to Cu²⁺ and Cd²⁺, respectively. The multiple antibiotic resistance (MAR) indices indicated that the cage cultured silver catfish and red hybrid tilapia were under high exposure to the tested antibiotic. Overall, the results of the present studies showed that Sungai Manir may be polluted with heavy metal and antibiotic residues.     

BTH对小麦产生白粉病抗性的诱导作用

用化学诱抗剂BTH(benzothiadiazole)分别处理幼苗期和成株期小麦后,再接种小麦白粉病菌,以研究BTH诱发小麦对白粉病产生系统性抗性的能力。结果表明,用BTH处理幼苗期小麦后,小麦白粉病的病情指数较对照显著降低,BTH诱发小麦幼苗对白粉病产生抗性的最佳浓度为0.20~0.25mmol/L,最佳时间间隔应大于6d。对于成株期小麦,在分蘖中期和后期以0.20mmol/LBTH喷雾,对小麦白粉病的防效为60.82%,较对照增产16.00%。说明BTH可以诱导小麦对白粉病产生系统获得抗性,并可用于田间白粉病防治。     

Characteristics of interspecific hybrids between <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis> and <Emphasis Type="Italic">P. eryngii</Emphasis>

In this study, three species of oyster mushroom (Pleurotus osturatus, P. eryngii and P. cornucopia) were crossed together in order to aggregate benefit special attributes to the genotype (s). The monokaryon of each of these species was prepared. Then, the monokaryons of two species were placed at 5 mm distance from each other to produce dikaryon. The results showed that, from among 700 crosses, only the crosses of eryngii and osturatus monokaryons were grown toward each other and produced clamps (dikaryons). Four produced hybrids were noted H₁, H₃₂, H₁₁ and H₄₀. The spans of produced hybrids were prepared; then, they were grown into sterile media and attributions of hybrids were studied. The results indicated that H₁₁ hybrid was an appropriate hybrid in terms of the number of days until growing, number of days until the observation of the first pin and the days from planting to harvest. However, H₄₀ was the best hybrid based on cap diameter, dry and fresh weight of fruit body, yield and biomass. It is expected that these interspecific hybrids employ for future oyster mushroom breeding programs.     

人工合成小麦对几种主要病害的抗性鉴定与评价

为了解人工合成六倍体小麦抗病性及其潜在利用价值,以95份人工合成小麦为试验材料,在人工接种全蚀病和条锈病、自然诱发白粉病和根腐叶枯病条件下,系统调查人工合成小麦对4种病害的田间抗病情况。结果表明,人工合成小麦中有较高比例的抗病材料,对全蚀病高抗以上材料占21%;对条锈病高抗以上材料占30%;对白粉病高抗以上材料占21%;对根腐叶枯病高抗以上材料占23%。CI93、CI108、CI187对全蚀病表现高抗、对其他3种叶部病害表现免疫,CI94对全蚀病、条锈病和白粉病表现高抗,对根腐叶枯病表现免疫,CI158、CI160、CI166对4种病害都表现高抗。     

Reactive oxygen species are involved in cell death in wheat roots against powdery mildew

Inoculation of wheat(Triticum aestivum L.) leaves with wheat powdery mildew fungus(Blumeria graminis f. sp. tritici) induces the cell death in adventitious roots. Reactive oxygen species(ROS) play a key role in respond to biotic stress in plants. To study the involvement of ROS and the degree of cell death in the wheat roots following inoculation, ROS levels and microstructure of root cells were analyzed in two wheat cultivars that are susceptible(Huamai 8) and resistant(Shenmai 8) to powdery mildew fungus. At 18 d after powdery mildew fungus inoculation, only Huamai 8 displayed the leaf lesions, while root cell death occurred in both varieties. Huamai 8 had a high level of ROS accumulation, which is associated with increased root cell degradation, while in Shenmai 8, there was little ROS accumulation correlating with slight root cell degradation. The molecular study about the expression levels of ROS scavenging genes(MnSOD and CAT) in wheat roots showed that these genes expression decreased after the leaves of wheat was inoculated. The difference between Huamai 8 and Shenmai 8 on subcellular localization of H2 O2 and O2–· was corresponded with the different down-regulation of the genes encoding for superoxide dismutase and catalase in two wheat cultivars. These results suggested that ROS were involved in the process by which powdery mildew fungus induced cell death in wheat roots.