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1.
Sheath rot disease of rice caused by Sarocladium oryzae (Sawada) (=Acrocylindrium oryzae, Sawada) has become an important production constraint in all rice-growing countries. Pathogenicity, phytotoxic metabolites, and random amplified polymorphic DNA (RAPD) markers were used to assess the level of genetic variability of S. oryzae derived from rice cultivars, CR1018, IR36, and IR50, of different locations in North East and South India. Variability in pathogenicity, phytotoxic metabolite production, and DNA polymorphisms was detected among S. oryzae isolates. Results indicated that S. oryzae isolates produced both cerulenin and helvolic acid at concentrations 0.3–0.62 and 0.9–4.8 μg mL−1 of culture filtrate, respectively. Isolates that produce higher concentration of helvolic acid induced a high percent incidence of sheath rot disease. Oligonucleotide primers, GF and MR, generated either a simple (up to 2 bands) or complex (up to 6 bands) RAPD pattern. According to their level of similarity, S. oryzae isolates from North East and South India were grouped separately into two major clusters and 13 genotypes. Molecular- and pathogenicity-based classifications were not correlated, but a high level of genetic variability within S. oryzae isolates was identified. The molecular variability of S. oryzae isolates will be an important consideration in breeding programs to develop durable resistance for sheath rot disease. 相似文献
2.
Spray of ethrel (1000 ppm)to seedlings of double-cropping second season rice at 5-leaf stage can control plant height and root length, and consequently makes seedlings strong and tough. The ABA content and ethylene released by young seedling were significantly higher than the control. However, there were some changes: cell elongation inhibited, leaf area decreased, and leaf color became dark green, photosynthetic rate increased, translocation of photosynthetate in leaf sheath enhanced, leaf emergence was rapid. The growth of root system and root vigor were though temporarily inhibited, but slightly increased after transplantation. All these are beneficial to seedling quality, the plant growth and development after transplantation, which subsequently bring about positive effects on stimulating early heading and on increasing rice yield. 相似文献
3.
4.
Glynn NC Ray R Edwards SG Hare MC Parry DW Barnett CJ Beck JJ 《Journal of applied microbiology》2007,102(6):1645-1653
AIMS: To develop sensitive quantitative PCR assays for the two groups of pathogens responsible for Fusarium seedling blight in wheat: Fusarium group (Fusarium culmorum and Fusarium graminearum) and Microdochium group (Microdochium nivale and Microdochium majus); and to use the assays to assess performance of fungicide seed treatments against each group. METHODS AND RESULTS: Primers conserved between the species within each group were used to develop competitive PCR assays and used to quantify DNA of each group in wheat seed produced from inoculated field plots. Seed was used in seed treatment efficacy field experiments and the amount of DNA of each group was determined in emerged seedlings. The performance of treatments towards each group of pathogens was evaluated by comparison of the reduction in DNA in seedlings emerged from treated seed compared with untreated seed. CONCLUSIONS: DNA from the two groups of pathogens causing Fusarium seedling blight of wheat can be quantified separately using the competitive PCR assays. These assays show improved sensitivity compared with those previously reported for the individual species and allowed the quantification of pathogen DNA in seed and seedlings. Significant reductions in pathogen DNA were evident for each seed treatment. SIGNIFICANCE AND IMPACT OF THE STUDY: Quantification of DNA for each group allows the evaluation of seed treatment performance towards the two components of Fusarium seedling blight disease complex. The approach taken and the assays developed in this study will be of use for the study of other Fusarium disease complexes and their control. Based on the results reported here on the seedling stage of crop development, further studies that examine the control of seed-borne pathogens through fungicide seed treatments throughout the growing season are warranted. 相似文献
5.
S. VEERASAMY 《Botanical journal of the Linnean Society. Linnean Society of London》1982,85(2):147-152
Polyembryony and twin seedlings are noted in Borassus flabellifer L. Both seedlings arising from a seed have an independent hatistorium, cotyledonary sheath, scale leaf and root system. There are instances where twin seedlings are identical in structure and activity; independent plants develop in the same way as normal seedlings. The haustoria of these seedlings are equal in size and activity. Cases are also recorded with disparity in size and activity between twin seedlings. While the haustorium of the bigger seedling is normal, that of the smaller seedling is reduced. 相似文献
6.
A number of nutritional problems have been reported for production of rice (Oryza sativa L.) on organic soils (Histosols). One of these, termed rice-seedling chlorosis, occurs when rice is drill-seeded into certain drained Histosols, and results in chlorotic, weakened seedlings that often die before or during imposition of the permanent flood. The condition can be predicted on the basis of soil testing and can be prevented by applying water-soluble Fe with the seed at planting. Greenhouse and field studies were conducted to determine the degree to which this problem can be corrected by the use of post-emergence foliarly applied Fe when the condition is not attended to at planting. It was determined that foliar application of Fe improved seedling growth, reduced seedling mortality, and increased rice grain production relative to no treatment. Nevertheless, prediction by the use of soil testing and prevention by application of Fe at seeding appears to be a more effective method for correcting seedling chlorosis than post-emergence foliar application of Fe.Florida Agricultural Experiment Station, Journal Series No. R-01230. 相似文献
7.
Effects of simulated acid rain on germination,seedling growth and oxidative metabolism of recalcitrant‐seeded Trichilia dregeana grown in its natural seed bank
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Chandika Ramlall Boby Varghese Syd Ramdhani Norman W. Pammenter Arvind Bhatt Patricia Berjak Sershen 《Physiologia plantarum》2015,153(1):149-160
Increased air pollution in a number of developing African countries, together with the reports of vegetation damage typically associated with acid precipitation in commercial forests in South Africa, has raised concerns over the potential impacts of acid rain on natural vegetation in these countries. Recalcitrant (i.e. desiccation sensitive) seeds of many indigenous African species, e.g. must germinate shortly after shedding and hence, may not be able to avoid exposure to acid rain in polluted areas. This study investigated the effects of simulated acid rain (rainwater with pH adjusted to pH 3.0 and 4.5 with 70:30, H2SO4:HNO3) on germination, seedling growth and oxidative metabolism in a recalcitrant‐seeded African tree species Trichilia dregeana Sond., growing in its natural seed bank. The results suggest that acid rain did not compromise T. dregeana seed germination and seedling establishment significantly, relative to the control (non‐acidified rainwater). However, pH 3.0 treated seedlings exhibited signs of stress typically associated with acid rain: leaf tip necrosis, abnormal bilobed leaf tips, leaf necrotic spots and chlorosis, reduced leaf chlorophyll concentration, increased stomatal density and indications of oxidative stress. This may explain why total and root biomass of pH 3.0 treated seedlings were significantly lower than the control. Acid rain also induced changes in the species composition and relative abundance of the different life forms emerging from T. dregeana's natural seed bank and in this way could indirectly impact on T. dregeana seedling establishment success. 相似文献
8.
Sarocladium oryzae is a filamentous fungus, commonly related to sheath rot, a disease until recently considered of low relevance but whose frequency has increased worldwide in rice cultivation. Few research groups have studied this microorganism, and consequently, the knowledge concerning biochemical and genetic factors that differentiate isolates within populations in terms of virulence (virulence factors/phytotoxin production) is limited. Some works have demonstrated that avirulent isolates of S. oryzae may act as biological control agents (BCAs), primarily due to their high potential for production of the secondary metabolite cerulenin, a potent antifungal. For these reasons, the goal of this paper is to review what is known about the virulence factors of S. oryzae, to highlight the main secondary metabolites produced by the fungus and their role in sheath rot development, and to try to establish a relationship between virulent, avirulent and potential BCA strains of S. oryzae. 相似文献
9.
Kenjiro Tadera Fumio Yagi Shoji Minemoto Akira Kobayashi 《Bioscience, biotechnology, and biochemistry》2013,77(6):1453-1456
Cycasin, the toxic glycoside of cycad plants, interfered with seed germination and seedling growth of Gramineae, Crucifereae and Leguminosae. The shoots and roots of seedlings showed wilting, chlorosis and necrosis. Rice plants were most sensitive and soybean plants rather tolerant.Respiration and α-amylase activity were markedly low in the rice seedlings treated with cycasin. Both cycasin and its aglycone, methylazoxymethanol, did not inhibit the activity of α-amylase, but did suppress the formation of α-amylase in rice endosperms. Exogenous gibberellin considerably reversed the inhibition of germination and growth, and the suppression of α-amylase formation caused by these toxins. 相似文献
10.
A polymerase chain reaction (PCR) technique was developed for detecting the presence of Xanthomonas oryzae pv. oryzae, the bacterial leaf blight (BLB) pathogen in rice seed and for studying the transmission of this bacterium from seed to plant. Primers TXT and TXT4R from an insertion sequence (IS1113) of the pathogen were used to amplify a 964-bp DNA fragment. A combined biological and enzymatic amplification (BIO-PCR) technique was used to detect the pathogen in naturally infected seed. The level of detection of TXT and TXT4R primers was 55 fg DNA of X. o. pv. oryzae, which is roughly the equivalent of seven cells (and four cells in pure culture suspension) of X. o. pv. oryzae. Hybridization of IS1113 with the amplified DNA fragment in Southern blot analysis confirmed that the 964-bp DNA fragment was amplified from X. o. pv. oryzae. The presence of the IS1113 element in strains of X. o. pv. oryzae from 16 rice-growing countries was confirmed by DNA dot blot analysis. X. o. pv. oryzae was detected from the seed washes and DNA extracted from the seed washes of naturally infected seeds of cvs Jaya and TN1. When stored at 4 degrees C, the pathogen was recovered up to 4 months and 9 months from naturally infected seeds of cvs Jaya and TN1, respectively. The BLB bacterium was also detected in seedlings, mature plants and seeds collected from plants raised from naturally infected seeds. 相似文献
11.
连作花生土壤中酚酸类物质的检测及其对花生的化感作用 总被引:25,自引:0,他引:25
研究了南方红壤区不同连作年限花生土壤中酚酸物质的种类、含量,及其对花生生长的影响。结果表明:连作花生土壤中对羟基苯甲酸、香草酸和香豆酸随着连作年限的增加而增加,连作10a后3种酚酸总量达11.09mg·kg-1干土,显著高于连作3a和6a的土壤;而土壤中香豆素和苯甲酸含量比较低,且变化没有规律。所有酚酸处理组对花生幼苗的株高和根长表现出抑制作用,对花生幼苗地下部的干鲜重均表现出"低促高抑"的特点。香草酸和香豆酸处理组对花生幼苗地上部的干鲜重表现出"低促高抑"的特点,其他处理组均表现出抑制作用。花生幼苗根系活力随着酚酸处理浓度的增加而降低,花生幼苗的超氧化物歧化酶活力(SOD)、过氧化物酶活力(POD)、丙二醛含量(MDA)则随着酚酸浓度的增加而增加。与只用茄腐镰刀菌孢子悬液浸泡花生种子的对照相比,加入酚酸后,花生种子的病原菌的感染率随着酚酸浓度的增加而增加,发芽率则随着酚酸浓度的增加而下降。以上结果说明,酚酸物质可以抑制花生幼苗的生长和提高花生的发病率,可能是因为酚酸物质破坏花生细胞膜的完整性而使病原菌入侵,影响花生生长,产生连作障碍。 相似文献
12.
In Sun Hwang Woo-Ri Kang Duk-Ju Hwang Shin-Chul Bae Sung-Hwan Yun Il-Pyung Ahn 《Journal of microbiology (Seoul, Korea)》2013,51(6):858-865
Bakanae disease caused by Fusarium fujikuroi is an important fungal disease in rice. Among the seven strains isolated from symptomatic rice grains in this study, one strain, FfB14, triggered severe root growth inhibition and decay in the crown and root of rice seedlings. The remaining six strains caused typical Bakanae symptoms such as etiolation and abnormal succulent rice growth. To reveal the relationship between mycelial growth in the infected tissues and Bakanae disease progression, we have established a reliable quantification method using real time PCR that employs a primer pair and dual-labeled probe specific to a unigene encoding F. fujikuroi PNG1 (FfPNG1), which is located upstream of the fumonisin biosynthesis gene cluster. Plotting the crossing point (CP) values from the infected tissue DNAs on a standard curve revealed the active fungal growth of FfB14 in the root and crown of rice seedlings, while the growth rate of FfB20 in rice was more than 4 times lower than FfB14. Massive infective mycelial growth of FfB14 was evident in rice stems and crown; however, FfB20 did not exhibit vigorous growth. Our quantitative evaluation system is applicable for the identification of fungal virulence factors other than gibberellin. 相似文献
13.
Floral and seedling morphology and anatomy of Thalassodendron pachyrhizum den Hartog (cymodoceaceae)
《Aquatic Botany》1987,29(1):1-17
Thalassodendron pachyrhizum den Hartog is dioecious with inflorescences on short laterals from upright stems. The male inflorescence consists of two flowers which are morphologically identical but developmentally different. Each male flower has two laterally fused anthers, each of which contains four loculi surrounding a vascular bundle. Filiform pollen grains are arranged in coils. The walls of pollen grains contain cellulosic microfibrils embedded in a protein and carbohydrate matrix, and lack an exine layer. The female inflorescence produces two morphologically and developmentally identical flowers, each having an ovary with a short style containing two vascular bundles and leading to two long, slender stigmas. Both male and female inflorescences are enclosed in several alternating bracts. The innermost bract differs from the others by lacking a ligule. Squamulae intravaginales are present in all inflorescences. In each inflorescence, only one ovary develops into the seed which germinates on the parent plant. Young seedlings have an aril-like structure which disappears at a later stage of seedling development. The seedling produces, firstly, an aberrant seedling leaf and a scarious seedling sheath, then several true foliage leaves and finally several root primordia. The mature seedling separates from its protecting bract and detaches from the parent plant. The floral and seedling morphology and anatomy are compared with other closely related genera in the Cymodoceaceae and unique features are assessed. The frequency of floral and seedling production is discussed in relation to the distribution of T. pachyrhizum. 相似文献
14.
水稻苗期低温失绿的遗传分析及基因定位 总被引:3,自引:0,他引:3
在早季低温条件下, 籼稻品种Dular的幼苗表现出白化失绿, 而粳稻品种Lemont幼苗表现正常绿色。以Lemont和Dular作亲本构建一个F2群体,通过该群体在早季低温条件下性状的表现,发现Lemont和Dular苗期耐冷性的差异受单个主基因控制,低温下白化失绿等位基因为隐性。将该基因暂时命名为cisc(t)。利用该F2群体,采用集团分离分析(BSA)法将cisc(t)定位在9号染色体上。经过对F2群体中100个典型的白化单株的简单序列长度多态性分析,将该基因定位在5.5 cM的区间内,分别与微卫星标记RM257和RM242相距3.9 cM和1.6 cM。 相似文献
15.
Wen-Xu Li Hai-Jun Zhao Wei-Qin Pang Hai-Rui Cui Yves Poirier Qing-Yao Shu 《Transgenic research》2014,23(4):585-599
Phytic acid (PA) is poorly digested by humans and monogastric animals and negatively affects human/animal nutrition and the environment. Rice mutants with reduced PA content have been developed but are often associated with reduced seed weight and viability, lacking breeding value. In the present study, a new approach was explored to reduce seed PA while attaining competitive yield. The OsMRP5 gene, of which mutations are known to reduce seed PA as well as seed yield and viability, was down-regulated specifically in rice seeds by using an artificial microRNA driven by the rice seed specific promoter Ole18. Seed PA contents were reduced by 35.8–71.9 % in brown rice grains of transgenic plants compared to their respective null plants (non-transgenic plants derived from the same event). No consistent significant differences of plant height or number of tillers per plant were observed, but significantly lower seed weights (up to 17.8 % reduction) were detected in all transgenic lines compared to null plants, accompanied by reductions of seed germination and seedling emergence. It was observed that the silencing of the OsMRP5 gene increased the inorganic P (Pi) levels (up to 7.5 times) in amounts more than the reduction of PA-P in brown rice. This indicates a reduction in P content in other cellular compounds, such as lipids and nucleic acids, which may affect overall seed development. Put together, the present study demonstrated that seed specific silencing of OsMRP5 could significantly reduce the PA content and increase Pi levels in seeds; however, it also significantly lowers seed weight in rice. Discussions were made regarding future directions towards producing agronomically competitive and nutritionally valuable low PA rice. 相似文献
16.
Iwai T Kaku H Honkura R Nakamura S Ochiai H Sasaki T Ohashi Y 《Molecular plant-microbe interactions : MPMI》2002,15(6):515-521
Bacterial attack is a serious agricultural problem for growth of rice seedlings in the nursery and field. The thionins purified from seed and etiolated seedlings of barley are known to have antimicrobial activity against necrotrophic pathogens; however, we found that no endogenous rice thionin genes alone are enough for resistance to two major seed-transmitted phytopathogenic bacteria, Burkholderia plantarii and B. glumae, although rice thionin genes constitutively expressed in coleoptile, the target organ of the bacteria. Thus, we isolated thionin genes from oat, one of which was overexpressed in rice. When wild-type rice seed were germinated with these bacteria, all seedlings were wilted with severe blight. In the seedling infected with B. plantarii, bacterial staining was intensively marked around stomata and intercellular spaces. However, transgenic rice seedlings accumulating a high level of oat thionin in cell walls grew almost normally with bacterial staining only on the surface of stomata. These results indicate that the oat thionin effectively works in rice plants against bacterial attack. 相似文献
17.
Responses of Pinus clausa, Pinus serotina and Pinus taeda seedlings to anaerobic solution culture. I. Changes in growth and root morphology 总被引:2,自引:0,他引:2
Seedlings of pond pine ( Pinus serotina Michx.), sand pine [ P. clausa (Engelm.) Sarg.] and two edaphic seed sources of loblolly pine ( P. taeda L., dry- and wet-site seed sources) were grown in non-circulating, continuously flowing solution culture under aerobic (250 μ M O2 ) and anaerobic (≤ 23 μ M O2 ) conditions. Survival was 100% for all seedlings at 11 weeks. Although shoot height, biomass and leaf emergence of loblolly and pond pine seedlings were not significantly affected by 15 or 30 days of anaerobic growth conditions, root biomass was significantly reduced. Sand pine suffered the largest reduction in biomass, showing extensive root dieback and shoot chlorosis with retarded leaf development. These anaerobically induced symptoms of flooding injury were less severe in dry-site loblolly pine, and absent in wet-site loblolly and pond pine seedlings. Adventitious or new, secondary roots, and stem or taproot lenticels were particularly abundant under the 30-day anaerobic treatment in wet-site loblolly and pond pine seedlings, present to a lesser degree in dry-site loblolly pine, and nearly absent in sand pine seedlings. These results indicate that much of the immediate damage from flooding is due to the anoxic condition of the root rather than to the build-up of phytotoxins or soil nutrient imbalances. On the basis of overall seedling vigor, root plasticity and growth, we suggest the following flooding-tolerance/intolerance species (seed source) gradient: pond pine ≥ wet-site loblolly pine > dry-site loblolly pine > sand pine. 相似文献
18.
生活污水尾水灌溉对麦秸还田水稻幼苗及土壤环境的影响 总被引:2,自引:0,他引:2
通过盆栽试验研究了麦秸还田下生活污水尾水灌溉对水稻幼苗和土壤环境的影响.测定了不同处理水稻幼苗根系形态、根系活力、分蘖、株高、干物质累积量、土壤亚铁、有机酸、酶活性.结果表明: 与自来水灌溉相比,不施化肥氮时,生活污水尾水灌溉显著提高了水稻移栽后41 d的分蘖数和根系活力;正常施氮肥时,生活污水尾水灌溉显著促进了水稻根系和植株生长,根长、根表面积、根体积、根系活力、水稻分蘖数和干物质累积量均显著高于自来水灌溉处理.生活污水尾水灌溉处理显著降低了土壤Fe2+和有机酸含量,土壤脲酶、过氧化氢酶活性等显著提高.生活污水尾水灌溉和施氮耦合能有效缓解秸秆还田初期对水稻幼苗生长的不利影响,改善水稻生长状况,提升土壤肥力和质量. 相似文献
19.
Annia Hernández-Rodríguez Mayra Heydrich-Pérez Billo Diallo Mondher El Jaziri Olivier M. Vandeputte 《Plant Growth Regulation》2010,60(3):191-197
The saprophytic bacterium Burkholderia
cepacia has been shown to play an active role as plant growth promoting bacteria (PGPB). In this study, the ability of cell-free
culture medium (CFCM) of B. cepacia to improve early developmental stages of plants has been assessed on two agronomically important crops, maize (Zea
mays) and rice (Oryza
sativa). Treating maize and rice seeds for 45 min before germination significantly improved seed germination and consequent seedling
growth. The effect of CFCM was confirmed by the increased biomass of the shoot and, mainly, the root systems of treated seedlings.
Chromatographic characterization of the CFCM revealed that the spent culture medium of B. cepacia is a complex mix of different classes of metabolites including, among others, salicylic acid, indole-3-acetic acid (IAA)
and several unidentified phenolic compounds. Fractionation of the CFCM components revealed that the impressive development
of the root system of CFCM-treated seedlings is due to the synergistic action of several groups of components rather than
IAA alone. The data presented here suggest that a CFCM of B. cepacia can be used to improve crop germination. 相似文献
20.
E. Duveiller K. Miyajima F. Snacken A. Autrique H. Maraite 《Journal of Phytopathology》1988,122(2):97-107
In various pathogenicity, serological, physiological and biochemical tests, performed in Belgium and Japan, the Pseudomonas fuscovaginae strains associated above 1,350 m elevation in Burundi with sheath brown rot of rice, rusty seed and black, stripes on seedlings, were found to be similar to reference strains of this pathogen from Japan. The same bacteria was detected on rice seeds imported from Asia to Burundi. Beside the serological characteristics, P. fuscovaginae can be differentiated from other oxidase and arginine dihydrolase positive non-pathogenic fluorescent pseudomonads, also isolated from lesions on rice seedlings, by the simultaneous occurrence of no production of 2-ketogluconate, acid production from trehalose, but not from inositol. Occasionally, other symptoms inducing, oxidase positive, fluorescent pseudomonads, different from any described species, were isolated from rice seedlings and sheath rot in Burundi. 相似文献