Mechanisms of pathogenesis in Sclerotium bataticola on sunflowers. 1. Production and translocation of a necrosis-inducing toxin

1969 ◽  
Vol 47 (7) ◽  
pp. 1147-1151 ◽  
Author(s):  
Yu-Ho Chan ◽  
W. E. Sackston
Keyword(s):  
Activated Carbon ◽  
Root System ◽  
Vascular System ◽  
Early Symptom ◽  
Vascular Tissues ◽  
Detached Leaves ◽  
Necrotic Spots ◽  
Whole Plants ◽  
Necrotic Spotting

Necrotic spotting of leaves is an early symptom of attack by Sclerotium bataticola on sunflowers. Spots appear after invasion of vascular tissues by the pathogen, which does not spread appreciably from the point of inoculation.Inoculation of one stem of plants split apically to give twin stems on one root system resulted in necrotic spotting of leaves first on the inoculated, and later on the uninoculated stem. Introducing cell-free filtrates of cultures of S. bataticola into sunflower plants or detached leaves resulted in production of the same type of necrotic spots. Introduction of eosin dye, which is translocated in the vascular system, into whole plants and detached leaves produced patterns of coloration similar to the patterns of necrotic spotting. The necrosis may be attributed to a translocatable toxin produced by the fungus.It is indicated that the toxin is neither an enzyme nor a protein. It has not been eluted after adsorption by activated carbon.

scholarly journals Influence of leaf age on infection of Actinidia species by Pseudomonas syringae pv actinidiae

2015 ◽  
Vol 68 ◽  
pp. 328-331 ◽  
Author(s):  
J.L. Tyson ◽  
I.J. Horner ◽  
C.L. Curtis ◽  
A. Blackmore ◽  
M.A. Manning
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Age ◽  
Detached Leaf Assay ◽  
Detached Leaf ◽  
Detached Leaves ◽  
Necrotic Spots ◽  
Whole Plants

The influence of leaf age on infection of Actinidia species by Pseudomonas syringae pv actinidiae (Psa) was investigated using two approaches (a) inoculation of potted Hayward and Hort16A kiwifruit plants and (b) inoculation of whole leaves in a detached leaf assay Whole plants and detached leaves were spray inoculated with Psa biovar 3 (haplotype NZV; PsaV) and maintained in a saturated environment Flecking was evident on some of the leaves 8 days after inoculation Many of the flecks later became necrotic spots with halos similar to the Psa leaf infections that have been observed in the field With both methods a higher percentage of leaves that were 13 weeks of age at inoculation had flecking and spotting than did leaves of other ages Leaves that were 7 weeks or older did not show any symptoms of infection by Psa Overall leaves of Hort16A showed slightly more flecking and spotting than Hayward

Virulence of Soybean Aphid, Aphis glycines (Hemiptera: Aphididae) Clones on Detached Leaves and Whole Plants

2020 ◽  
Vol 92 (3) ◽  
pp. 497 ◽  
Author(s):  
Doris Lagos-Kutz ◽  
Michelle L. Pawlowski ◽  
Brian W. Diers ◽  
Swapna R. Purandare ◽  
Kelley J. Tilmon ◽  
...  
Keyword(s):  
Soybean Aphid ◽  
Aphis Glycines ◽  
Detached Leaves ◽  
Whole Plants

scholarly journals Exogenous auxin improves root morphology and restores growth of grafted cucumber seedlings

2017 ◽  
Vol 44 (No. 2) ◽  
pp. 82-90 ◽  
Author(s):  
Balliu Astrit ◽  
Sallaku Glenda
Keyword(s):  
Root System ◽  
Root Morphology ◽  
Soil Conditions ◽  
Cucumber Seedlings ◽  
Faster Development ◽  
Whole Plants ◽  
Indole 3 Acetic Acid ◽  
Different Levels ◽  
Morphology Parameters ◽  
Establishment Rate

The aim of this study was to investigate the effects of exogenously applied auxin over the rootstock cuttings on root morphology parameters and stand establishment rate of salt-stressed cutting grafted cucumber seedlings. For that purpose, before grafting, the cut ends of the rootstocks were soaked for few seconds into auxin solution (indole-3-acetic acid (IAA) or indole-3- butyric acid (IBA))at different concentrations and afterwards were grafted by the root pruned splice grafting (RPSG) method. Ten days after grafting, the grafted seedlings were transplanted into individual pots where two different levels of salt-stress (0 and 50 mM) were established. Root morphology parameters, as well as dry matter of the root system and the whole plants were successively analysed to randomly selected plants. Exogenous auxins improved root morphology parameters and restored root growth under salinity conditions. The best results were obtained through the application of IBA, which promoted a better rootstock – scion relationship, presumably due to faster development of phloem and xylem tubes, and the promotion of a vigorous root system which increases plant’s absorbing capabilities for water and nutrients under adverse soil conditions.

scholarly journals First Report of Colletotrichum acutatum on Strawberry in Northwestern Argentina

Plant Disease ◽  
2000 ◽  
Vol 84 (6) ◽  
pp. 706-706 ◽  
Author(s):  
C. J. Ramallo ◽  
L. D. Ploper ◽  
M. Ontivero ◽  
M. P. Filippone ◽  
A. Castagnaro ◽  
...  
Keyword(s):  
Colletotrichum Acutatum ◽  
Conidial Suspension ◽  
Disease Symptoms ◽  
Northwestern Argentina ◽  
First Report ◽  
Surface Control ◽  
Detached Leaves ◽  
Strawberry Anthracnose ◽  
Pathogenicity Tests ◽  
Necrotic Spots

Isolates were obtained from strawberry tissue with anthracnose symptoms from several locations near Tucumán, Argentina. Isolates were characterized using several criteria. Isolates produced fusiform conidia, tapered to a point at both ends, and averaged 13.5 × 4.9 μm. On potato dextrose agar, colonies produced a white cottony mycelial colony that turned orange in older cultures. Compared with Colletotrichum fragariae, the new isolates produced fewer appressoria. Pathogenicity tests were conducted on detached leaves and plants in the greenhouse and field. Detached immature leaves of cvs. Chandler, Fern, and Sweet Charlie were inoculated with a 20-μl droplet of an aqueous conidial suspension (106 conidia per ml) placed on the adaxial surface. Control leaves were inoculated with sterile distilled water. Leaves were maintained under white light (2,000 lux, 12 h/day) at 26°C, and 100% relative humidity. Necrotic spots were visible 4 days after inoculation. Greenhouse and field plants were spray-inoculated and covered for 48 h. Disease symptoms were mainly observed on petioles and runners 9 days after inoculation. No lesions were observed on control detached leaves or plants. Koch's postulates were confirmed in all cases. Based on morphological and cultural characteristics, isolates were identified as C. acutatum Simmonds (1). This is the first report of C. acutatum causing strawberry anthracnose in northwestern Argentina. Reference: (1) B. Smith and L. L. Black. Plant Dis. 74:69, 1990.

scholarly journals The Source of Rag5-Mediated Resistance to Soybean Aphids Is Located in the Stem

2021 ◽  
Vol 12 ◽  
Author(s):  
Kumud Joshi ◽  
Joshua L. Baumgardner ◽  
Madison MacPhail ◽  
Shailesh R. Acharya ◽  
Elizabeth Blotevogel ◽  
...  
Keyword(s):  
Management Strategies ◽  
The United States ◽  
Electrical Penetration Graph ◽  
Feeding Behaviors ◽  
Soybean Aphids ◽  
Whole Plant ◽  
Detached Leaves ◽  
Root Stock ◽  
Plant Assays ◽  
Whole Plants

The soybean aphid (Aphis glycines) continues to threaten soybean production in the United States. A suite of management strategies, such as planting aphid-resistant cultivars, has been successful in controlling soybean aphids. Several Rag genes (resistance against A. glycines) have been identified, and two are currently being deployed in commercial soybean cultivars. However, the mechanisms underlying Rag-mediated resistance are yet to be identified. In this study, we sought to determine the nature of resistance conferred by the Rag5 gene using behavioral, molecular biology, physiological, and biochemical approaches. We confirmed previous findings that plants carrying the Rag5 gene were resistant to soybean aphids in whole plant assays, and this resistance was absent in detached leaf assays. Analysis of aphid feeding behaviors using the electrical penetration graph technique on whole plants and detached leaves did not reveal differences between the Rag5 plants and Williams 82, a susceptible cultivar. In reciprocal grafting experiments, aphid populations were lower in the Rag5/rag5 (Scion/Root stock) chimera, suggesting that Rag5-mediated resistance is derived from the shoots. Further evidence for the role of stems comes from poor aphid performance in detached stem plus leaf assays. Gene expression analysis revealed that biosynthesis of the isoflavone kaempferol is upregulated in both leaves and stems in resistant Rag5 plants. Moreover, supplementing with kaempferol restored resistance in detached stems of plants carrying Rag5. This study demonstrates for the first time that Rag5-mediated resistance against soybean aphids is likely derived from stems.

scholarly journals Molecular Changes Concomitant with Vascular System Development in Mature Galls Induced by Root-Knot Nematodes in the Model Tree Host Populus tremula × P. alba

2020 ◽  
Vol 21 (2) ◽  
pp. 406 ◽  
Author(s):  
Fabien Baldacci-Cresp ◽  
Marc Behr ◽  
Annegret Kohler ◽  
Nelly Badalato ◽  
Kris Morreel ◽  
...  
Keyword(s):  
Cell Wall ◽  
Secondary Cell Wall ◽  
De Novo ◽  
Vascular System ◽  
System Development ◽  
Primary Cell Wall ◽  
Root Knot Nematode ◽  
Vascular Differentiation ◽  
Vascular Tissues ◽  
Model Tree

One of the most striking features occurring in the root-knot nematode Meloidogyne incognita induced galls is the reorganization of the vascular tissues. During the interaction of the model tree species Populus and M. incognita, a pronounced xylem proliferation was previously described in mature galls. To better characterise changes in expression of genes possibly involved in the induction and the formation of the de novo developed vascular tissues occurring in poplar galls, a comparative transcript profiling of 21-day-old galls versus uninfected root of poplar was performed. Genes coding for transcription factors associated with procambium maintenance and vascular differentiation were shown to be differentially regulated, together with genes partaking in phytohormones biosynthesis and signalling. Specific signatures of transcripts associated to primary cell wall biosynthesis and remodelling, as well as secondary cell wall formation (cellulose, xylan and lignin) were revealed in the galls. Ultimately, we show that molecules derived from the monolignol and salicylic acid pathways and related to secondary cell wall deposition accumulate in mature galls.

Garlic Mustard (Alliaria petiolata) Removal Method Affects Native Establishment

2009 ◽  
Vol 2 (3) ◽  
pp. 230-236 ◽  
Author(s):  
E. Kathryn Barto ◽  
Don Cipollini
Keyword(s):  
Fractal Dimension ◽  
Activated Carbon ◽  
Plant Growth ◽  
Root Growth ◽  
Root System ◽  
Mycorrhizal Fungi ◽  
Alliaria Petiolata ◽  
First Year ◽  
Garlic Mustard ◽  
Entire Plant

AbstractWe used a growth chamber experiment with first-year garlic mustard plants to explore the effects of three garlic mustard removal techniques (treatment with glyphosate, pulling out the entire plant, and clipping the shoot) on growth of the native herb pale jewelweed and its associated mycorrhizal fungi. We also explored the effects of activated carbon and mycorrhizal inocula amendments. We monitored plant height, intra- and extraradical mycorrhizal structures, root growth, and the fractal dimension of the root system. Removing as much garlic mustard root tissue as possible by hand pulling plants led to larger jewelweed plants than other removal methods. Activated carbon and mycorrhizal inocula did not improve plant growth.

THE EFFECT OF SODIUM DIMETHYLDITHIOCARBAMATE ON WATER UPTAKE, TRANSPIRATION, AND STOMATAL OPENING

1964 ◽  
Vol 42 (10) ◽  
pp. 1405-1410 ◽  
Author(s):  
G. D. Thorn ◽  
W. H. Minshall
Keyword(s):  
Amino Acids ◽  
Root System ◽  
Water Uptake ◽  
Water Movement ◽  
Stomatal Opening ◽  
Large Reduction ◽  
Root Pressure ◽  
Bean Plants ◽  
Detached Leaves ◽  
Total Amino Acids

Sodium dimethyldithiocarbamate, applied to the roots of tomato and bean plants, markedly decreases the rate of transpiration and prevents stomatal opening. The chemical also causes a large reduction in water movement associated with metabolic root pressure. The concentration of total amino acids moving out of the root system is reduced by as much as 50% of normal. Transpiration and stomatal opening of detached leaves from untreated plants are not affected appreciably by solutions of sodium dimethyldithiocarbamate.

Accumulation of hypoxanthine in potato leaves and its effect on spore germination in Phytophthora infestans

1968 ◽  
Vol 46 (3) ◽  
pp. 267-270 ◽  
Author(s):  
M. C. Clark ◽  
O. T. Page
Keyword(s):  
Aqueous Solution ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Spore Germination ◽  
Detached Leaves ◽  
Whole Plants

The accumulation of hypoxanthine (6-hydroxypurine) in blighted potato leaves and its effect on spore germination in the late blight organism, Phytophthora infestans, were investigated. Preliminary experiments on the translocation of this compound in whole plants and detached leaves were also conducted.Under in vitro and in vivo conditions, hypoxanthine had a pronounced stimulatory effect on the indirect germination of sporangia. Studies on the movement of this base indicate that it is freely translocated, but fails to be exported from detached leaves into aqueous solution. These observations, coupled with the finding that hypoxanthine readily accumulated in blighted leaves, suggest that this compound could be of importance in predisposing uninfected portions of the host to invasion by the pathogen.

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