The systemic nature of the sunflower disease caused by Diaporthe helianthi

1991 ◽  
Vol 69 (7) ◽  
pp. 1552-1556 ◽  
Author(s):  
M. Muntanola-Cvetković ◽  
Jelena Vukojević ◽  
M. Mihaljčević
Keyword(s):  
Plant Diseases ◽  
Leaf Axil ◽  
Plant Tissues ◽  
Conducting System ◽  
Intercellular Spaces ◽  
Histological Studies ◽  
Leaf Petiole ◽  
Diaporthe Helianthi ◽  
Xylem Elements ◽  
Systemic Nature

The systemic nature of the disease of sunflower plants caused by Diaporthe helianthi, the leaf–petiole–stem route of the host invasion by the fungus, and the plant tissues that were successively affected were demonstrated through histological studies. After penetration into the host, the infection hyphae invade the intercellular spaces and terminal veinlets of the lamina and spread toward larger branches of the conducting system, the midrib, and the petiole. Xylem elements are invaded but are affected less by the fungus attack than the phloem and the parenchyma tissues, which disintegrate completely. Hyphae spread through the leaf axil to the tissues of the stem cortex, where pycnidia of the Phomopsis anamorph are initiated from internal masses of mycelium. Key words: systemic plant diseases, sunflower diseases, Diaporthe helianthi, Phomopsis helianthi.

scholarly journals Histological studies on the development of Phoma root rot of alfalfa

1969 ◽  
Vol 89 (3-4) ◽  
pp. 251-262
Author(s):  
Rocío del P. Rodríguez
Keyword(s):  
Root Rot ◽  
Cell Walls ◽  
Enzymatic Degradation ◽  
Cortical Cell ◽  
Host Responses ◽  
Histological Studies ◽  
Tissue Degradation ◽  
Electron And Light Microscopy ◽  
Xylem Elements ◽  
Scanning Electron

Several stages of the disease cycle of root rot of alfalfa caused by Phoma medicaginis var. medicaginis were studied by using scanning electron and light microscopy. First activity of the pathogen was the external colonization of the root. The pathogen penetrated directly causing discoloration and tissue disintegration. Inter- and intracellular penetration facilitated by enzymatic degradation was likely the mechanism involved in breaching the barrier of the epidermal cells. Colonization of the cortex was intercellular. Radial access to the xylem elements was achieved through the cortex. Host responses to invasion by the pathogen were suberization of cortical cell walls and occlusion of vessels with pectic substances and wound gum. Cavities in the cortex resulting from tissue degradation were associated with later stages of infection. Intracellular hyphae were observed in dead cells of the cortex and in the xylem. 

Pericarp micromorphology and dehydration characteristics of Quercus suber L. acorns

2000 ◽  
Vol 10 (3) ◽  
pp. 401-407 ◽  
Author(s):  
Eduardo Sobrino-Vesperinas ◽  
Ana Belén Viviani
Keyword(s):  
Water Loss ◽  
External Surface ◽  
Quercus Suber ◽  
Vascular Bundles ◽  
Palisade Layer ◽  
Intercellular Spaces ◽  
Cell Layers ◽  
Poorly Differentiated ◽  
Xylem Elements ◽  
The Mean

AbstractThe aim of the present study was to examine the micromorphology of the cork-oak (Quercus suber) acorn and to evaluate the efficiency of the pericarp as a barrier to water loss. When the desiccation curve obtained at 25 ± 1°C and 62% RH for physiologically mature acorns collected from the tree was compared with that corresponding to fully ripe acorns which had been shed, the latter showed a slightly lower rate of water loss. A marked reduction in the mean rate of water loss was recorded for intact acorns compared with those from which the pericarp had been removed. The external surface and transverse sections of the pericarp from both mature and fully ripe acorns were examined by scanning electron microscopy. Two zones presenting morphological and micromorphological differences were identified: an area including the point of attachment to the cupule and an apical zone covering the embryo. The microstructure of the pericarp showed an external thick cuticle and a single external palisade layer of closely packed cells with no intercellular spaces. Underlying this layer, there was a further parenchymatous layer of poorly differentiated, roughly isodiametric cells. The pericarp in the cupular zone consisted of only this undifferentiated layer between the two epidermal cell layers and contained vascular bundles with many xylem elements.

scholarly journals Definition of Tissue-Specific and General Requirements for Plant Infection in a Phytopathogenic Fungus

2001 ◽  
Vol 14 (3) ◽  
pp. 300-307 ◽  
Author(s):  
Marie Dufresne ◽  
Anne E. Osbourn
Keyword(s):  
Map Kinase ◽  
Magnaporthe Grisea ◽  
Plant Diseases ◽  
Gaeumannomyces Graminis ◽  
Phytopathogenic Fungus ◽  
Plant Tissues ◽  
Leaf Blast ◽  
Tissue Specific ◽  
Leaf Spots ◽  
Plant Infection

Although plant diseases are usually characterized by the part of the plant that is affected (e.g., leaf spots, root rots, wilts), surprisingly little is known about the factors that condition the ability of pathogens to colonize different plant tissues. Here we demonstrate that the leaf blast pathogen Magnaporthe grisea also can infect plant roots, and we exploit this finding to distinguish tissue-specific and general requirements for plant infection. Tests of a M. grisea mutant collection identified some mutants that were defective specifically in infection of either leaves or roots, and others such as the map kinase mutant pmk1 that were generally defective in pathogenicity. Conservation of a functional PMK1-related MAP kinase in the root pathogen Gaeumannomyces graminis was also demonstrated. Exploitation of the ability of M. grisea to infect distinct plant tissues thus represents a powerful tool for the comprehensive dissection of genetic determinants of tissue specificity and global requirements for plant infection.

scholarly journals Sap Beetle (Coleoptera: Nitidulidae) Management in Strawberries

EDIS ◽  
1969 ◽  
Vol 2004 (16) ◽  
Author(s):  
Silvia I. Rondon ◽  
James F. Price ◽  
Daniel J. Cantliffe
Keyword(s):  
Cooperative Extension Service ◽  
Plant Diseases ◽  
Extension Service ◽  
Plant Tissues ◽  
Publication Date ◽  
Stored Products ◽  
University Of Florida ◽  
Sap Beetle ◽  
Plant Parts ◽  
Sap Beetles

Sap beetles (Coleoptera: Nitidulidae) are conspicuous arthropods that feed on flowers, fruits, sap, fungi, stored products, decaying and fermenting plant tissues from diverse trees and crops, including strawberries. Sap beetles work in association with yeasts and other fungi causing the fermentation of infested plant parts (Fig. 1). They also are known to transport a variety of microorganisms that cause plant diseases; a few species can behave as predators of various ornamental pests (Dowd, 1991; Dowd and Weber, 1991). Sap beetles are often considered minor pests; however, their main impact is due to the contamination of products caused by adults and larvae. This document is HS993, one of a series of the Horticultural Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication date: October 2004. HS993/HS234: Sap Beetle (Coleoptera: Nitidulidae) Management in Strawberries (ufl.edu)

scholarly journals The microscopic diagnostic signs of some Fabaceae L. genus representatives. Message ІІ. Plant conducting system

2021 ◽  
Vol 14 (3) ◽  
pp. 292-298
Author(s):  
O. V. Grechana ◽  
A. H. Serbin ◽  
A. M. Rudnyk ◽  
O. O. Salii
Keyword(s):  
Trifolium Pratense ◽  
Water Solution ◽  
Microscopic Analysis ◽  
System Structure ◽  
Central Vein ◽  
Conducting System ◽  
Leaf Petiole ◽  
Dicotyledonous Plants ◽  
Trifolium Pratense L ◽  
Conductive System

The world plant products market is expanded rapidly and trade in them tends to grow by 15–25 % annually. The number of reports is increased proportionally about accidental contamination or deliberate, economically motivated falsification of plant raw materials. 27 % of the nearly 6.000 herbal preparations that are sold in 37 countries have contained undeclared contaminants, substitutes, or other components, according to the literature. We have conducted a plant conduction system microscopic analysis of the individual members’ genus Clover (Trifoliae L.), Fabaceae L. to identify morphoanatomical characteristics. Clover has anti-inflammatory, antiseptic, choleretic, diaphoretic, diuretic, hemostatic, expectorant, astringent properties and is used in many diseases. Aim. The finding common features and those that differ and can be used as diagnostic during studying the conducting system structure of genus Trifolium L. leaves and stems. Materials and methods. Plant material (herb) from Trifolium pratense L., T. incarnatum L., T. repens L. and T. fragiferum L. was harvested during the active flowering period – (May – June) and was dried in a well-ventilated place. Leaves and stems preparations were pre-boiled in 5 % sodium hydroxide water solution and fixed in chloral hydrate solution. Cross-sections were made with a microtome. The BIOLAM LOMO light microscope (Russia) and OLYMPUS SH-21 digital camera were used to record the data about identify the conducting apparatus of the plant’s leaf, petiole, and stem. Results. It has been examined the central vein structure of T. pratense L. and T. fragiferum L. leaves, it was determined that the conductive system is covered with a crystalline coating and there is one closed collateral bundle in the center, which is not typical for dicotyledonous plants. The petioles of T. incarnatum L., T. fragiferum L., and T. repens L. in cross-section are several different shapes. There are kidney-shaped and round. The conducting apparatus T. incarnatum L. and T. repens L. have arranged in a circle, closed and collateral. The leafstalk structure type of T. fragiferum L. is bunchles. It contradicts too the information about the structure conducting system of dicotyledonous plants. The stem’s conducting bundles are collateral and open. Conclusions. We have paid attention to the structural peculiarities of the conductive system of the central vein and petiole of objects for study: Trifolium pratense L., T. incarnatum L., T. repens L., and T. fragiferum L. when searching for differentiating features in some members of the genus Trifoliae L. in pharmacognostic analysis. The Dicotyledonae representatives are not characteristic of the closed type of conductive bundles, which we observed during microscopic examination.

scholarly journals A Genome-Wide Analysis of Antibiotic Producing Genes in Streptomyces globisporus SP6C4

2021 ◽  
Vol 37 (4) ◽  
pp. 389-395
Author(s):  
Da-Ran Kim ◽  
Youn-Sig Kwak
Keyword(s):  
Bacterial Species ◽  
Gene Clusters ◽  
Antimicrobial Activities ◽  
Plant Diseases ◽  
Local Alignment ◽  
Plant Tissues ◽  
Biosynthetic Gene ◽  
Genome Wide Analysis ◽  
Genome Wide ◽  
A Genome

Soil is the major source of plant-associated microbes. Several fungal and bacterial species live within plant tissues. Actinomycetes are well known for producing a variety of antibiotics, and they contribute to improving plant health. In our previous report, Streptomyces globisporus SP6C4 colonized plant tissues and was able to move to other tissues from the initially colonized ones. This strain has excellent antifungal and antibacterial activities and provides a suppressive effect upon various plant diseases. Here, we report the genome-wide analysis of antibiotic producing genes in S. globisporus SP6C4. A total of 15 secondary metabolite biosynthetic gene clusters were predicted using antiSMASH. We used the CRISPR/Cas9 mutagenesis system, and each biosynthetic gene was predicted via protein basic local alignment search tool (BLAST) and rapid annotation using subsystems technology (RAST) server. Three gene clusters were shown to exhibit antifungal or antibacterial activity, viz. cluster 16 (lasso peptide), cluster 17 (thiopeptide-lantipeptide), and cluster 20 (lantipeptide). The results of the current study showed that SP6C4 has a variety of antimicrobial activities, and this strain is beneficial in agriculture.

scholarly journals First Report on the Association of a 16SrII-A Phytoplasma with Sesame (Sesamum indicum) Exhibiting Abnormal Stem Curling and Phyllody in Taiwan

Plant Disease ◽  
2014 ◽  
Vol 98 (7) ◽  
pp. 990-990 ◽  
Author(s):  
Y.-W. Tseng ◽  
W.-L. Deng ◽  
C.-J. Chang ◽  
J.-W. Huang ◽  
F.-J. Jan
Keyword(s):  
Nested Pcr ◽  
Early Stage ◽  
Sesamum Indicum ◽  
Plant Tissues ◽  
Oilseed Crop ◽  
Universal Primer ◽  
Sieve Elements ◽  
First Report ◽  
Leaf Petiole ◽  
Rdna Sequences

Sesame (Sesamum indicum L.), an annual plant, is grown as an oilseed crop and the seeds are used in bakery products in Taiwan. In June 2013, plants exhibiting symptoms including phyllody and abnormal stem curling were observed in sesame fields in Pitou Township, Changhua County, Taiwan. Incidence of infected plants was estimated to be greater than 90% within a single field. Phytoplasmas associated with sesame exhibiting phyllody, witches'-broom, or virescence have been classified as strains of 16SrI-B in Myanmar (GenBank Accession No. AB558132), 16SrII-A in Thailand (JN006075), 16SrII-D in Oman (EU072505) and India (KF429486), 16SrIV-C in Iran (JF508515), and 16SrVI-A (KF156894) and 16SrIX (KC139791) in Turkey (1). Three symptomatic and four asymptomatic plants were uprooted and transplanted in a greenhouse for further study. Transmission electron microscopy (TEM) revealed clusters of phytoplasma cells ranging from 300 to 800 nm in diameter only in phloem sieve elements of stems of three symptomatic and two asymptomatic plants. Comparable tissues from two other symptomless plants were devoid of phytoplasma cells. Total DNA was extracted with a modified CTAB method (2) from plant tissues (100 mg each) including stem, leaf, petiole, and root from the same plants used for TEM work. Analyses by a nested PCR using universal primer pairs P1/P7 (5′-AAGAGTTTGATCCTGGCTCAGGATT/5′-CGTCCTTCATCGGCTCTT) followed by R16F2n/R16R2 (5′-GAAACGACTGCTAAGACTGG/5′-TGACGGGCGGTGTGTACAAACCCCG) were performed to detect putative phytoplasma DNA (3). Each primer pair amplified a single PCR product of either 1.8 or 1.2 kb, respectively, only from the three symptomatic and two asymptomatic plant tissues that had phytoplasma cells in their sieve elements. It is likely that these two asymptomatic plants were in the early stage of infection before symptoms became noticeable. The nested PCR products (1.2 kb) amplified from the symptomatic plants were cloned separately and sequenced (GenBank Accession Nos. KF923391, KF923392, and KF923393). BLAST analysis of the sequences revealed that they shared 99.2% sequence identity with strains reported from India and Thailand (KF429486 and JN006075), which were classified to the 16SrII-D and 16SrII-A subgroups, respectively. Moreover, iPhyClassifier software (4) was used to perform sequence comparison and generate a virtual restriction fragment length polymorphism (RFLP) profile. The 16S rDNA sequences shared 99.4% identity with that of the ‘Candidatus Phytoplasma australasiae’ (Y10097) and the RFLP patterns were identical to that of the 16SrII-A subgroup, indicating the Taiwanese strain is a ‘Ca. P. australasiae’-related strain. To our knowledge, this is the first report of a 16SrII-A subgroup phytoplasma causing phyllody and abnormal stem curling on sesame in Taiwan. The occurrence of phytoplasma on sesame could have direct implications for the cultivation of this economically important oilseed plant and the bakery industry in Taiwan. References: (1) M. Catal et al. Plant Dis. 97:835, 2013. (2) T. M. Fulton et al. Plant Mol. Biol. Rep. 13:207, 1995. (3) D. E. Gundersen and I. M. Lee. Phytopathol. Mediterr. 35:144, 1996. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

Peronospora hyoscyami f. sp. tabacina. [Descriptions of Fungi and Bacteria].

1989 ◽  
Author(s):  
G. Hall
Keyword(s):  
Geographical Distribution ◽  
Infected Plant ◽  
Weather Conditions ◽  
Plant Diseases ◽  
Plant Tissues ◽  
Airborne Spores ◽  
Distribution Maps ◽  
Blue Mould ◽  
Leaf Spots ◽  
The Usa

Abstract A description is provided for Peronospora hyoscyami f. sp. tabacina. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Naturally infected: Capsicum annuum, Nicotiana alpina, N. acuminata, N. attenuata, N. benthamiana, N. bigelowii, N. caesia, N. glauca, N. glutinosa, N. langsdorffi, N. longiflora, N. mesophila, N. nodiflora, N. nudicaulis, N. paniculata, N. quadrivalvis, N. repanda, N. rustica, N.x sanderae, N. stocktoni, N. suavolens, N. sylvestris, N. tabacum, N. tomentosa, N. trigonophylla, N. wigandioides, Solanum lycopersicum, S. melongena, S. nigrum.Infected experimentally: Capsicum frutescens, Dunalia ramiflora, Hyoscyamus muticus, H. niger, Nicotiana alata, N. affnis, N. cavanillesii, N. fragrans, N. gossei, N. goodspeedii, N. ipomopsifolia, N. maritima, N. megalosiphon, N. raimondii, N. tomentosifolius, Lehmania otophora, Physalis alkekangi, P. lanceifolia, P. peruviana, Petunia × hybrida, Schizanthus pinnatus. DISEASE: Blue mould of tobacco plants (48, 3141; 61, 2664) (commercial and ornamental varieties are affected); the fungus is an obligately biotrophic plant pathogen. Chlorotic leaf spots develop on leaves of susceptible seedlings, which become deformed. Undersurfaces of leaves become covered with a layer of sporophores, producing a diagnostic blue-grey felt. Rapid generalized light-brown tissue necrosis follows and the apical meristem ceases growth. Disease symptoms may not appear immediately after infection, however, or during sporophore production. If the fungus encounters any barrier to its growth through the plant tissues (because of a physiological response, high temperature or fungicides), then the infection becomes wholly systemic, being confined to an area close to the veins, or to a necrotic area if the plant is genetically resistant. Similar symptoms develop on mature plants in the field and the entire plant may be destroyed within 3-4 weeks, leaving only a blackened stem. The fungus attacks leaves and stems of tobacco seedlings and mature plants in Europe and Australia, but only leaf tissues in the USA, where weather conditions confine it to being a seedling disease in most years. GEOGRAPHICAL DISTRIBUTION: First reported in Australia in 1891, now worldwide; see CMI Distribution Maps of Plant Diseases 23. TRANSMISSION: By airborne spores, which can remain viable for 2 months at 20-40% RH, and have been reported to be transported over distances of 1, 600 km. Most favourable conditions for sporulation are an average temperature of 20°C and a period of relatively high humidity (95% RH) for at least 3 h. Spore liberation is dependent on a rise in temperature, a decrease in relative humidity and an increase in insolation. There is some evidence for soil-borne transmission by oospores in infected plant debris in the USA, since blue mould appears more often in seedbeds which have previously contained infected tobacco. Although mycelium can survive and overwinter in plant tissues, there are no reports of transmission by a systemic route.

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