Histopathology comparison and phenylalanine ammonia lyase (PAL) gene expressions in Fusarium wilt infected watermelons

2008 ◽  
Vol 59 (12) ◽  
pp. 1146 ◽  
Author(s):  
P.-F. L. Chang ◽  
C.-C. Hsu ◽  
Y.-H. Lin ◽  
K.-S. Chen ◽  
J.-W. Huang ◽  
...  
Keyword(s):  
Fusarium Wilt ◽  
Phenylalanine Ammonia Lyase ◽  
Citrullus Lanatus ◽  
Spontaneous Mutation ◽  
Limiting Factors ◽  
Lower Percentage ◽  
Post Inoculation ◽  
Infested Soil ◽  
Gene Expressions ◽  
Shoot Base

Fusarium wilt disease of watermelon (Citrullus lanatus (Thunb.) Matsum & Nakai), caused by Fusarium oxysporum f. sp. niveum (FON), is one of the limiting factors of worldwide watermelon production. In this study, a Fusarium wilt resistant watermelon JSB, which was derived from a spontaneous mutation of the susceptible Sugar Baby (SB), was used to investigate histopathology. The number and diameter of xylem vessels in the root (10 mm below the shoot base) of resistant JSB plants were significantly higher than those in susceptible SB plants. At 9 days post inoculation (dpi), using the plate assay on Nash-PCNB media, FON could be recovered from 86% of the roots in the symptomless plants of both watermelon lines, and from 55% and 64% of the stem segments (5 mm above the shoot base) in resistant and susceptible plants, respectively. In paraffin and free-hand tissue sections, at 8, 13, and 35 dpi, the xylem of roots and stems close to the soil surface in resistant watermelon JSB plants was also colonised by FON, but to a much lower percentage than the susceptible SB ones. No colonisation below the middle of stems was observed in the resistant JSB plants. The susceptible plants grown in infested soil were all dead by 35 dpi, while the resistant plants remained healthy. These observations suggest that reducing FON colonisation in the vascular systems of the host may contribute to the resistance in JSB. Furthermore, the higher expression of the phenylalanine ammonia lyase (PAL) gene in JSB induced by FON and the effects of PAL inhibitor on the resistance of JSB suggested that PAL is involved in resistance of watermelon to Fusarium wilt pathogen.

Cell wall reinforcement in watermelon shoot base related to its resistance to Fusarium wilt caused by Fusarium oxysporum f. sp. niveum

2014 ◽  
Vol 153 (2) ◽  
pp. 296-305 ◽  
Author(s):  
T.-H. CHANG ◽  
Y.-H. LIN ◽  
K.-S. CHEN ◽  
J.-W. HUANG ◽  
S.-C. HSIAO ◽  
...  
Keyword(s):  
Cell Wall ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Cell Walls ◽  
Phenylalanine Ammonia Lyase ◽  
Signal Molecules ◽  
Vascular Bundles ◽  
Structural Barriers ◽  
Shoot Base ◽  
Bound Phenolics

SUMMARYFusarium wilt of watermelon, caused by Fusarium oxysporum f. sp. niveum, is one of the limiting factors for watermelon production in Taiwan. In recent research, the phenylalanine ammonia lyase (PAL) gene expressed in the shoot base of the Fusarium wilt resistant line JSB was related to Fusarium wilt resistance. Phenylalanine ammonia lyase is the key regulatory enzyme in the phenylpropanoid metabolic pathway. The downstream products of phenolic compounds are considered to be involved in the complicated plant defence mechanisms. They could act as signal molecules, antimicrobial substances and/or structural barriers. To study the resistant mechanisms of Fusarium wilt, the resistant JSB line was examined for comparison of F. oxysporum-watermelon interactions with the susceptible Grand Baby (GB) cultivar. Unlike infected GB, which was seriously colonized by F. oxysporum in the whole plant, the pathogen was limited below the shoot base of inoculated JSB, suggesting that the shoot base of JSB may contribute to Fusarium resistance. The data indicated that a significant increase in PAL activity was found in shoot bases of the resistant JSB line at 3, 9, 12 and 15 days after inoculation (DAI). Shoot bases of resistant watermelons accumulated higher amounts of soluble and cell wall-bound phenolics at 3–9 DAI; the susceptible GB cultivar, however, only increased the cell wall-bound phenolics in shoot bases at 3 DAI. High lignin deposition in the cell walls of vascular bundles was observed in the shoot bases of JSB but not of GB seedlings at 6 and 9 DAI. In the roots and shoot bases of JSB seedlings at 6 DAI, peroxidase enzyme activity increased significantly. In summary, the results suggest that accumulation of cell wall-bound phenolics and increase of peroxidase activity in shoot bases of JSB seedlings during F. oxysporum inoculation, together with the rapid deposition of lignin in the cell walls of vascular bundles, may have provided structural barriers in resistant JSB line to defend against F. oxysporum invasion.

scholarly journals Race 3, a New and Highly Virulent Race of Fusarium oxysporum f. sp. niveum Causing Fusarium Wilt in Watermelon

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 92-98 ◽  
Author(s):  
X. G. Zhou ◽  
K. L. Everts ◽  
B. D. Bruton
Keyword(s):  
Fusarium Oxysporum ◽  
Host Range ◽  
Fusarium Wilt ◽  
Citrullus Lanatus ◽  
Genetic Difference ◽  
Infested Soil ◽  
Reference Isolate ◽  
New Race ◽  
Race 2 ◽  
Highly Virulent

Three races (0, 1, and 2) of Fusarium oxysporum f. sp. niveum have been previously described in watermelon (Citrullus lanatus) based on their ability to cause disease on differential watermelon genotypes. Four isolates of F. oxysporum f. sp. niveum collected from wilted watermelon plants or infested soil in Maryland, along with reference isolates of races 0, 1, and 2, were compared for virulence, host range, and vegetative compatibility. Race identification was made on the watermelon differentials Sugar Baby, Charleston Gray, Dixielee, Calhoun Gray, and PI-296341-FR using a root-dip, tray-dip, or pipette inoculation method. All four Maryland isolates were highly virulent, causing 78 to 100% wilt on all differentials, one of which was PI-296341-FR, considered highly resistant to race 2. The isolates also produced significantly greater colonization in the lower stems of PI-296341-FR than a standard race 2 reference isolate. In field microplots, two of the isolates caused over 90% wilt on PI-296341-FR, whereas no disease was caused by a race 2 isolate. All four isolates were nonpathogenic on muskmelon, cucumber, pumpkin, and squash, confirming their host specific pathogenicity to watermelon. The Maryland isolates were vegetatively compatible to each other but not compatible with the race 2 isolates evaluated, indicating their genetic difference from race 2. This study proposes that the Maryland isolates belong to a new race, race 3, the most virulent race of F. oxysporum f. sp. niveum described to date.

Effects of Host Resistance and Inoculum Density on the Suppression of Fusarium Wilt of Watermelon Induced by Hairy Vetch

Plant Disease ◽  
2007 ◽  
Vol 91 (1) ◽  
pp. 92-96 ◽  
Author(s):  
X. G. Zhou ◽  
K. L. Everts
Keyword(s):  
Fusarium Wilt ◽  
Citrullus Lanatus ◽  
Inoculum Density ◽  
Disease Suppression ◽  
Management Tool ◽  
Infested Soil ◽  
Hairy Vetch ◽  
Inoculum Level ◽  
Resistance Level ◽  
Bacterial Populations

Hairy vetch (Vicia villosa) used as a soil amendment is a newly described potential management tool for the suppression of Fusarium wilt of watermelon (Citrullus lanatus). However, the effect of inoculum density and the level of resistance in the host on the level of suppression are not understood. In this study, hairy vetch-induced wilt suppression was evaluated in the greenhouse on 12 watermelon cultivars with different levels of wilt resistance and in 16 naturally infested soil samples collected from commercial watermelon fields. Wilt suppression occurred in all but two cultivars and with the trend that suppression increased as the level of resistance in cultivars increased. Fusarium wilt suppression was 22, 53, and 63% in hairy vetch-amended soil compared with nonamended soil on cultivars ranked as susceptible, moderately resistant, and highly resistant, respectively. Suppression also occurred in nine of the soils that contained populations of Fusarium oxysporum f. sp. niveum below 1,100 CFU/g of soil. However, at this level or higher, significant wilt suppression was not observed. The magnitude of disease suppression decreased with the increase of inoculum in the soils. The induced wilt suppression appeared to be correlated with an increase in bacterial populations in soil. Hairy vetch-induced suppression to Fusarium wilt in watermelon is dependent on the resistance level of cultivars and is overcome by high inoculum level of F. oxysporum f. sp. niveum in soil.

scholarly journals QTL Mapping Identifies Novel Source of Resistance to Fusarium Wilt Race 1 in Citrullus amarus

Plant Disease ◽  
2019 ◽  
Vol 103 (5) ◽  
pp. 984-989 ◽  
Author(s):  
Sandra E. Branham ◽  
Amnon Levi ◽  
W. Patrick Wechter
Keyword(s):  
Fusarium Wilt ◽  
Citrullus Lanatus ◽  
Recombinant Inbred Lines ◽  
The United States ◽  
Chromosome 9 ◽  
Mapping Study ◽  
Sources Of Resistance ◽  
Race 1 ◽  
Genetic Source ◽  
Genetic Mapping Study

Fusarium wilt race 1, caused by the soilborne fungus Fusarium oxysporum Schlechtend.: Fr. f. sp. niveum (E.F. Sm.) W.C. Snyder & H.N. Hans (Fon), is a major disease of watermelon (Citrullus lanatus) in the United States and throughout the world. Although Fusarium wilt race 1 resistance has been incorporated into several watermelon cultivars, identification of additional genetic sources of resistance is crucial if a durable and sustainable level of resistance is to be continued over the years. We conducted a genetic mapping study to identify quantitative trait loci (QTLs) associated with resistance to Fon race 1 in segregating populations (F2:3 and recombinant inbred lines) of Citrullus amarus (citron melon) derived from the Fon race 1 resistant and susceptible parents USVL246-FR2 and USVL114, respectively. A major QTL (qFon1-9) associated with resistance to Fon race 1 was identified on chromosome 9 of USVL246-FR2. This discovery provides a novel genetic source of resistance to Fusarium wilt race 1 in watermelon and, thus, an additional host-resistance option for watermelon breeders to further the effort to mitigate this serious phytopathogen.

scholarly journals Marker Development for Differentiation of Fusarium oxysporum f. sp. Niveum Race 3 from Races 1 and 2

2021 ◽  
Vol 22 (2) ◽  
pp. 822
Author(s):  
Owen Hudson ◽  
Sumyya Waliullah ◽  
James C. Fulton ◽  
Pingsheng Ji ◽  
Nicholas S. Dufault ◽  
...  
Keyword(s):  
South Carolina ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Conventional Polymerase Chain Reaction ◽  
Detection Methods ◽  
Limiting Factors ◽  
Pcr Marker ◽  
Primer Sets ◽  
Race Differentiation ◽  
Race 2

Fusarium wilt of watermelon, caused by Fusarium oxysporum f. sp. niveum (FON), is pathogenic only to watermelon and has become one of the main limiting factors in watermelon production internationally. Detection methods for this pathogen are limited, with few published molecular assays available to differentiate FON from other formae speciales of F. oxysporum. FON has four known races that vary in virulence but are difficult and costly to differentiate using traditional inoculation methods and only race 2 can be differentiated molecularly. In this study, genomic and chromosomal comparisons facilitated the development of a conventional polymerase chain reaction (PCR) assay that could differentiate race 3 from races 1 and 2, and by using two other published PCR markers in unison with the new marker, the three races could be differentiated. The new PCR marker, FNR3-F/FNR3-R, amplified a 511 bp region on the “pathogenicity chromosome” of the FON genome that is absent in race 3. FNR3-F/FNR3-R detected genomic DNA down to 2.0 pg/µL. This marker, along with two previously published FON markers, was successfully applied to test over 160 pathogenic FON isolates from Florida, Georgia, and South Carolina. Together, these three FON primer sets worked well for differentiating races 1, 2, and 3 of FON. For each marker, a greater proportion (60 to 90%) of molecular results agreed with the traditional bioassay method of race differentiation compared to those that did not. The new PCR marker should be useful to differentiate FON races and improve Fusarium wilt research.

scholarly journals Shoot Organogenesis and Plant Regeneration from Cotyledons of Diploid, Triploid, and Tetraploid Watermelon

1993 ◽  
Vol 118 (1) ◽  
pp. 151-157 ◽  
Author(s):  
Michael E. Compton ◽  
D.J. Gray
Keyword(s):  
Shoot Organogenesis ◽  
Citrullus Lanatus ◽  
Adventitious Shoots ◽  
Adventitious Shoot ◽  
Shoot Formation ◽  
Lower Percentage ◽  
Adventitious Shoot Formation ◽  
Optimized Protocol ◽  
Apical Half ◽  
Number Of Shoots

Adventitious shoots were obtained from watermelon [Citrullus lanatus (Thunb.) Matsun. & Nakai] cotyledons incubated on a modified Murashige and Skoog medium containing BA. Initial experiments comparing the effects of BA (0, 5, 10, or 20 μm) and IA4 (0, 0.5, or 5 μm) demonstrated that BA was required for adventitious shoot formation but its concentration in the medium was not critical. The addition of IAA to medium with BA increased callus production and inhibited shoot formation. However, the percentage of responding explants in the best treatment was <30%. Therefore, the manner in which cotyledon explants were prepared and seedling age at the time of explantation was examined to improve the organogenic response. The percentage of explants with shoots was improved by using explants that consisted of cotyledon bases (43%) or cotyledons cut in half longitudinally (39%). A lower percentage (16%) of cotyledons cut longitudinally into four pieces produced shoots. Explants taken from the apical half of cotyledons failed to regenerate shoots. Shoot formation was improved further by using explants from young seedlings. The percentage of explants with shoots was >90% for `Minilee', 64% for S86NE, and 50% for `Jubilee II' when explants were prepared from 5-day-old seedlings. Explants from nongerminated embryos or seedlings germinated for 10, 15, or 20 days produced fewer shoots. The effect of several cytokinins on shoot organogenesis was then examined using the optimized protocol. The percentage of explants with shoots and the number of shoots per explant were about two to four times higher when 5 to 10 μm BA was used compared to the most effective kinetin (20 μm) or thidiazuron (0.1 μm) concentration. The percentage of explants with shoots and the number of shoots per explant were greater for diploid (57% and 2.2, respectively) than for triploid (22% and 0.6, respectively) or tetraploid (20% and 0.8, respectively) lines. Chemical names used: N -(phenylmethyl)-1 H -purin-6-amine (BA); 6-furfurylaminopurine (kinetin); N -phenyl-N' -1,2,3-thiadiazol-5-ylurea (thidiazuron); 1 H -indole3-acetic acid (IAA).

scholarly journals Uncovering the Host Range for Maize Pathogen Magnaporthiopsis maydis

Plants ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 259 ◽  
Author(s):  
Dor ◽  
Degani
Keyword(s):  
Host Range ◽  
Citrullus Lanatus ◽  
Shoot Biomass ◽  
Pcr Analysis ◽  
Plant Residues ◽  
Infested Soil ◽  
Pathogenicity Test ◽  
Green Foxtail ◽  
Fungal Dna ◽  
Shoot Weight

The fungus Magnaporthiopsis maydis is a soil-borne, seed-borne vascular wilt pathogen that causes severe damage to sensitive Zea mays L. (maize) hybrids throughout Egypt, Israel, India, Spain, and other countries. It can undergo virulence variations and survive as spores, sclerotia, or mycelia on plant residues. Maize, Lupinus termis L. (lupine) and Gossypium hirsutum L. (cotton) are the only known hosts of M. maydis. Identification of new plant hosts that can assist in the survival of the pathogen is an essential step in restricting disease outbreak and spread. Here, by field survey and growth chamber pathogenicity test, accompanied by real-time PCR analysis, the presence of the fungal DNA inside the roots of cotton (Pima cv.) plants was confirmed in infested soil. Moreover, we identified M. maydis in Setaria viridis (green foxtail) and Citrullus lanatus (watermelon, Malali cv.). Infected watermelon sprouts had delayed emergence and development, were shorter, and had reduced root and shoot biomass. M. maydis infection also affected root biomass and phenological development of cotton plants but caused only mild symptoms in green foxtail. No M. maydis DNA was detected in Hordeum vulgare (barley, Noga cv.) and the plants showed no disease symptoms except for reduced shoot weight. These findings are an important step towards uncovering the host range and endophytic behavior of M. maydis, encouraging expanding this evaluation to other plant species.

scholarly journals In Planta and Soil Quantification of Fusarium oxysporum f. sp. ciceris and Evaluation of Fusarium Wilt Resistance in Chickpea with a Newly Developed Quantitative Polymerase Chain Reaction Assay

2011 ◽  
Vol 101 (2) ◽  
pp. 250-262 ◽  
Author(s):  
Daniel Jiménez-Fernández ◽  
Miguel Montes-Borrego ◽  
Rafael M. Jiménez-Díaz ◽  
Juan A. Navas-Cortés ◽  
Blanca B. Landa
Keyword(s):  
Polymerase Chain Reaction ◽  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Plant Root ◽  
Quantitative Polymerase Chain Reaction ◽  
Infested Soil ◽  
In Planta ◽  
Field Plot ◽  
Chain Reaction ◽  
Polymerase Chain

Fusarium wilt of chickpea caused by Fusarium oxysporum f. sp. ciceris can be managed by risk assessment and use of resistant cultivars. A reliable method for the detection and quantification of F. oxysporum f. sp. ciceris in soil and chickpea tissues would contribute much to implementation of those disease management strategies. In this study, we developed a real-time quantitative polymerase chain reaction (q-PCR) protocol that allows quantifying F. oxysporum f. sp. ciceris DNA down to 1 pg in soil, as well as in the plant root and stem. Use of the q-PCR protocol allowed quantifying as low as 45 colony forming units of F. oxysporum f. sp. ciceris per gram of dry soil from a field plot infested with several races of the pathogen. Moreover, the q-PCR protocol clearly differentiated susceptible from resistant chickpea reactions to the pathogen at 15 days after sowing in artificially infested soil, as well as the degree of virulence between two F. oxysporum f. sp. ciceris races. Also, the protocol detected early asymptomatic root infections and distinguished significant differences in the level of resistance of 12 chickpea cultivars that grew in that same field plot infested with several races of the pathogen. Use of this protocol for fast, reliable, and cost-effective quantification of F. oxysporum f. sp. ciceris in asymptomatic chickpea tissues at early stages of the infection process can be of great value for chickpea breeders and for epidemiological studies in growth chambers, greenhouses and field-scale plots.

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