scholarly journals The contributions to virulence of the effectors Eop1 and DspE differ between two clades of Erwinia tracheiphila strains

2021 ◽  
Author(s):  
Olakunle I Olawole ◽  
Qian Liu ◽  
Chiliang Chen ◽  
Mark L. Gleason ◽  
Gwyn A. Beattie
Keyword(s):  
Host Specificity ◽  
Cucumis Melo ◽  
Cucurbita Pepo ◽  
Host Preference ◽  
Erwinia Amylovora ◽  
Host Adaptation ◽  
Effector Proteins ◽  
Functional Evaluation ◽  
Erwinia Tracheiphila ◽  
Over Expression

Strains of Erwinia tracheiphila, causal agent of bacterial wilt of cucurbits, are divided into distinct clades. Et-melo clade strains wilt Cucumis spp. but not Cucurbita spp., thus exhibiting host specificity, whereas Et-C1 clade strains wilt Cucurbita spp. more rapidly than Cucumis melo, thus exhibiting a host preference. This study investigated the contribution of the effector proteins Eop1 and DspE to E. tracheiphila pathogenicity and host adaptation. Loss of eop1 did not enable Et-melo strains to infect squash (Cucurbita pepo) or an Et-C1 strain to induce a more rapid wilt of muskmelon (Cucumis melo), indicating that Eop1 did not function in host specificity or preference as in the related pathogen Erwinia amylovora. However, over-expression of eop1 from Et-melo strain MDCuke, but not from Et-C1 strain BHKY, increased the virulence of a BHKY eop1 deletion mutant on muskmelon, demonstrating that the Eop1 variants in the two clades are distinct in their virulence functions. Loss of dspE from Et-melo strains reduced but did not eliminate virulence on hosts muskmelon and cucumber, whereas loss of dspE from an Et-C1 strain eliminated pathogenicity on hosts squash, muskmelon and cucumber. Thus, the centrality of DspE to virulence differs in the two clades. Et-melo mutants lacking the chaperone DspF exhibited similar virulence to mutants lacking DspE, indicating that DspF is the sole chaperone for DspE in E. tracheiphila, unlike in E. amylovora. Collectively, these results provide the first functional evaluation of effectors in E. tracheiphila and demonstrate clade-specific differences in the roles of Eop1 and DspE.

scholarly journals Further Evidence of Cucurbit Host Specificity among Acidovorax citrulli Groups Based on a Detached Melon Fruit Pathogenicity Assay

2017 ◽  
Vol 107 (11) ◽  
pp. 1305-1311 ◽  
Author(s):  
Lichun Yan ◽  
Baishi Hu ◽  
Gong Chen ◽  
Mei Zhao ◽  
Ron R. Walcott
Keyword(s):  
Host Specificity ◽  
Crop Production ◽  
Host Preference ◽  
Specific Capacity ◽  
Effector Proteins ◽  
Acidovorax Citrulli ◽  
Group I ◽  
Group Ii ◽  
Melon Fruit ◽  
Fruit Rind

Bacterial fruit blotch, caused by the gram-negative bacterium Acidovorax citrulli, is a serious economic threat to cucurbit crop production worldwide. A. citrulli strains can be divided into two genetically distinct groups, with group I strains infecting a range of cucurbit species and group II strains being predominantly associated with watermelon. Group I and II A. citrulli strains differ in their arsenal of type III secreted (T3S) effector proteins and we hypothesize that these effectors are critical for cucurbit host preference. However, the pathogenicity or virulence assays used for A. citrulli, including infiltration of seedling cotyledons and mature fruit rind tissues with cell suspensions and spray inoculation of seedlings, lack the sensitivity to consistently distinguish strains of the two groups. Here, we describe an immature, detached melon fruit assay based on ‘Joaquin Gold’ melon (Syngenta, Rogers Brand) that clearly indicates differences in host specificity between group I and II A. citrulli strains. Using this assay, four group I strains (M6, AAC213-52, AAC213-55, and XJL12) induced typical water-soaked lesions in melon fruit rind tissue 7 to 10 days after pinprick inoculation. In contrast, four group II strains (AAC00-1, AAC213-44, AAC213-47, and AAC213-48) did not induce water-soaked lesions on detached melon fruit rinds during the same period. These data suggest that group I A. citrulli strains have a specific capacity to infect immature Joaquin Gold melon fruit, whereas group II strains do not. Interestingly, this differential pathogenicity phenotype was not observed on foliar seedling tissues of the same melon cultivar, suggesting that host preference of A. citrulli strains is specific to immature fruit tissues. Using the immature melon fruit inoculation assay, a T3S system mutant of the group I A. citrulli strain, M6 (M6ΔhrcV), failed to induce water soaking. This indicates that T3S effectors are involved in A. citrulli cucurbit host preference, and that this assay is suitable for future studies of unique T3S effectors that distinguish group I and II strains.

scholarly journals Differential Colonization Dynamics of Cucurbit Hosts by Erwinia tracheiphila

2016 ◽  
Vol 106 (7) ◽  
pp. 684-692 ◽  
Author(s):  
Cláudio M. Vrisman ◽  
Loïc Deblais ◽  
Gireesh Rajashekara ◽  
Sally A. Miller
Keyword(s):  
United States ◽  
Cucumis Melo ◽  
Host Preference ◽  
Plant Colonization ◽  
Northeastern United States ◽  
Erwinia Tracheiphila ◽  
Bioluminescent Bacteria ◽  
Daily Monitoring ◽  
Colonization Dynamics ◽  
Preferred Hosts

Bacterial wilt is one of the most destructive diseases of cucurbits in the Midwestern and Northeastern United States. Although the disease has been studied since 1900, host colonization dynamics remain unclear. Cucumis- and Cucurbita-derived strains exhibit host preference for the cucurbit genus from which they were isolated. We constructed a bioluminescent strain of Erwinia tracheiphila (TedCu10-BL#9) and colonization of different cucurbit hosts was monitored. At the second-true-leaf stage, Cucumis melo plants were inoculated with TedCu10-BL#9 via wounded leaves, stems, and roots. Daily monitoring of colonization showed bioluminescent bacteria in the inoculated leaf and petiole beginning 1 day postinoculation (DPI). The bacteria spread to roots via the stem by 2 DPI, reached the plant extremities 4 DPI, and the plant wilted 6 DPI. However, Cucurbita plants inoculated with TedCu10-BL#9 did not wilt, even at 35 DPI. Bioluminescent bacteria were detected 6 DPI in the main stem of squash and pumpkin plants, which harbored approximately 104 and 101 CFU/g, respectively, of TedCu10-BL#9 without symptoms. Although significantly less systemic plant colonization was observed in nonpreferred host Cucurbita plants compared with preferred hosts, the mechanism of tolerance of Cucurbita plants to E. tracheiphila strains from Cucumis remains unknown.

Host specificity of Argulus coregoni (Crustacea: Branchiura) increases at maturation

Parasitology ◽  
2007 ◽  
Vol 134 (12) ◽  
pp. 1767-1774 ◽  
Author(s):  
V. N. MIKHEEV ◽  
A. F. PASTERNAK ◽  
E. T. VALTONEN
Keyword(s):  
Host Specificity ◽  
Host Preference ◽  
Oxygen Depletion ◽  
Host Choice ◽  
Fish Host ◽  
Argulus Foliaceus ◽  
Argulus Coregoni ◽  
Suitable Habitats ◽  
Fish Hosts ◽  
Higher Sensitivity

SUMMARYWe tested the hypothesis that host specificity in ectoparasites does not depend exclusively on the features of the host but also on surrounding habitats, using 2 fish ectoparasites, Argulus coregoni and A. foliaceus (Crustacea: Branchiura), occurring sympatrically in Finnish lakes. Although these parasites are considered to be of low specificity, we found that the larger of the 2 species, A. coregoni developed a pronounced preference for salmonid hosts at the beginning of maturation (defined by the presence of copulating specimens). Argulus foliaceus infects a much wider range of fish hosts. We showed that specialization of A. coregoni on salmonids does not necessarily result from incompatibility with other fishes, but could instead reflect higher sensitivity of oxygen depletion compared with A. foliaceus. Adult A. coregoni may meet these demands by attaching to salmonids, the typical inhabitants of well-aerated waters. Young parasites of both species showed little host specificity and attached mainly to fishes with higher body reflectivity. In host choice experiments, A. coregoni of 4–5 mm length preferred salmonids (rainbow trout) to cyprinids (roach) irrespective of the type of fish host, on which it had been previously grown in the laboratory. We suggest that such an innate ontogenetic shift in host preference maintains the major part of the parasite population on its principal host, ensuring successful reproduction within suitable habitats.

scholarly journals Age-related Resistance of Diverse Cucurbit Fruit to Infection by Phytophthora capsici

2009 ◽  
Vol 134 (2) ◽  
pp. 176-182 ◽  
Author(s):  
Kaori Ando ◽  
Sue Hammar ◽  
Rebecca Grumet
Keyword(s):  
Cucumis Melo ◽  
Cucurbita Pepo ◽  
Citrullus Lanatus ◽  
Phytophthora Capsici ◽  
Vegetable Production ◽  
Age Related ◽  
Cucumber Fruit ◽  
Summer Squash ◽  
Pronounced Reduction ◽  
Green Stage

Phytophthora capsici causes severe losses in vegetable production, including many cucurbit crops. Our previous work showed that cucumber (Cucumis sativus) fruit are most susceptible to P. capsici when they are very young and rapidly elongating, but develop resistance as they approach full length at 10 to 12 days postpollination (DPP). In this study, fruit from seven additional cucurbit crops representing four species, melon (Cucumis melo), butternut squash (Cucurbita moschata), watermelon (Citrullus lanatus), and zucchini, yellow summer squash, acorn squash, and pumpkin (Cucurbita pepo), were tested for the effect of fruit development on susceptibility to P. capsici. Field-grown fruit of the different crops varied in overall susceptibility. Zucchini and yellow summer squash were the most susceptible, with the majority of fruit exhibiting water-soaking symptoms within 24 hours postinoculation. Fruit from all of the crops exhibited size-related decrease in susceptibility, but to varying degrees. Cucumber had the most pronounced effect. In infested fields, cucumber fruit were found to be most frequently infected at the blossom end. Comparison of the peduncle and blossom end showed a difference in susceptibility along the length of the fruit for cucumber, butternut squash, and zucchini. Greenhouse-grown, hand-pollinated pumpkin, acorn squash, and butternut squash showed an age-related decrease in susceptibility similar to field-grown fruit. For all of these fruit, a pronounced reduction in susceptibility accompanied the transition from the waxy green to green stage at ≈3 to 8 DPP.

scholarly journals EFEITO DO NÍVEL DE UMEDECIMENTO DO SUBSTRATO SOBRE A GERMINAÇÃO DE CUCURBITACEAS

1993 ◽  
Vol 23 (2) ◽  
pp. 157-160 ◽  
Author(s):  
Nilson Lemos de Menezes ◽  
Terezinha Lucia Denardin da Silveira ◽  
Lindolfo Storck
Keyword(s):  
Cucumis Sativus ◽  
Cucumis Melo ◽  
Cucurbita Pepo

Avaliou-se a germinação e o tamanho inicial das plântulas de pepino (Cucumis sativus), melancia (Citrulius lanatus), melão (Cucumis melo) e mogango (Cucurbita pepo) cujas sementes foram submetidas as condições do teste padrão de germinação, em rolos de papel toalha, umedecidas com as seguintes quantidades de água: 1,0; 1,5; 2,0; 2,5; 3,0 e 3,5 vezes o peso do papel. Os graus de umedecimento que proporcionam as maiores porcentagens de germinação para pepino e melancia são 2,0 a 2,5 vezes o peso do papel. Para o melão os melhores resultados de germinação são conseguidos com graus de umedecimento de 2,0 a 3,0 vezes o peso do papel, enquanto que para o mogango as quantidades de água requeridas são maiores do que para as demais espécies, devido ao maior tamanho de suas sementes. O aumento da quantidade de água no substrato proporciona aumentos no tamanho da parte aérea das Cucurbitaceas, porém o comprimento das raízes pode sofrer reduções variáveis, de acordo com a espécie estudada, quando a umidade está acima da faixa considerada ideal.

Weed Control with Fluazifop and Residues in Cucurbit Crops (Cucumissp.) and Sweet Potatoes (Ipomoea batatas)

Weed Science ◽  
1985 ◽  
Vol 33 (3) ◽  
pp. 405-410 ◽  
Author(s):  
Nancy Y. Parker ◽  
Thomas J. Monaco ◽  
Ross B. Leidy ◽  
Thomas J. Sheets
Keyword(s):  
North Carolina ◽  
High Performance Liquid Chromatography ◽  
Cucumis Melo ◽  
High Performance ◽  
Ipomoea Batatas ◽  
Cucurbita Pepo ◽  
Propanoic Acid ◽  
Sweet Potatoes ◽  
Annual Grasses ◽  
Repeated Applications

Fluazifop {(±)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid} controlled annual grasses in cucumbers (Cucumis sativusL. ‘Calypso’ and ‘Poinsett’), cantaloupe (Cucumis meloL. ‘Edisto 47’), zucchini squash (Cucurbita pepoL. ‘Elite’), and sweet potato (Ipomoea batatasL. ‘Jewel’) when applied as single or repeated applications of 0.3 or 0.6 kg ai/ha during 1982 and 1983 in North Carolina. All crops were generally tolerant to fluazifop and yields were equal to cultivated controls in all but one experiment. Residues detected in the various crops by high-performance liquid chromatography (HPLC) decreased as time elapsed between application and harvest increased. Approximately 1 ppm (w/w) of fluazifop was detected in cucumbers at 8 days after application, but residues were below the least detectable limit (0.05 ppm) when cucumbers, squash, and cantaloupe were harvested at 18 to 29 days after application. Fluazifop concentrations were 0.06 ppm or less in sweet potatoes at 55 days after application, and no fluazifop was detected at 84 days after application. Small cucumbers (<12 cm long) had greater fluazifop residues than larger fruit (>12 cm long) 20 days following application.

scholarly journals Genetic and Virulence Variability Among Erwinia tracheiphila Strains Recovered from Different Cucurbit Hosts

2013 ◽  
Vol 103 (9) ◽  
pp. 900-905 ◽  
Author(s):  
E. Saalau Rojas ◽  
P. M. Dixon ◽  
J. C. Batzer ◽  
M. L. Gleason
Keyword(s):  
Cucumis Melo ◽  
Geographic Origin ◽  
Strain Specificity ◽  
Plant Host ◽  
Erwinia Tracheiphila ◽  
Host Genus ◽  
Summer Squash ◽  
The Family ◽  
Polymerase Chain ◽  
Cucurbit Bacterial Wilt

The causal agent of cucurbit bacterial wilt, Erwinia tracheiphila, has a wide host range in the family Cucurbitaceae, including economically important crops such as muskmelon (Cucumis melo), cucumber (C. sativus), and squash (Cucurbita spp.). Genetic variability of 69 E. tracheiphila strains was investigated by repetitive-element polymerase chain reaction (rep-PCR) using BOXA1R and ERIC1-2 primers. Fingerprint profiles revealed significant variability associated with crop host; strains isolated from Cucumis spp. were clearly distinguishable from Cucurbita spp.-isolated strains regardless of geographic origin. Twelve E. tracheiphila strains isolated from muskmelon, cucumber, or summer squash were inoculated onto muskmelon and summer squash seedlings, followed by incubation in a growth chamber. Wilt symptoms were assessed over 3 weeks, strains were reisolated, and rep-PCR profiles were compared with the inoculated strains. Wilting occurred significantly faster when seedlings were inoculated with strains that originated from the same crop host genus (P<0.001). In the first run of the experiment, cucumber and muskmelon strains caused wilting on muskmelon seedlings at a median of 7.8 and 5.6 days after inoculation (dai), respectively. Summer squash seedlings wilted 18.0, 15.7, and 5.7 dai when inoculated with muskmelon-, cucumber-, and squash-origin strains, respectively. In a second run of the experiment, cucumber and muskmelon strains caused wilting on muskmelon at 7.0 and 6.9 dai, respectively, whereas summer squash seedlings wilted at 23.6, 29.0 and 9.0 dai when inoculated with muskmelon-, cucumber-, and squash-origin strains, respectively. Our results provide the first evidence of genetic diversity within E. tracheiphila and suggest that strain specificity is associated with plant host. This advance is a first step toward understanding the genetic and population structure of E. tracheiphila.

scholarly journals A lectin from the exudate of the fruit of the vegetable marrow (Cucurbita pepo) that has a specificity for β-1,4-linked N-acetylglucosamine oligosaccharides

1979 ◽  
Vol 183 (1) ◽  
pp. 133-137 ◽  
Author(s):  
A K Allen
Keyword(s):  
Affinity Chromatography ◽  
Cucumis Melo ◽  
Cucurbita Pepo ◽  
Polypeptide Chain ◽  
Soya Bean ◽  
Major Protein ◽  
Phloem Exudate ◽  
Single Polypeptide Chain ◽  
Vegetable Marrow ◽  
Single Polypeptide

Lectins are present in the exudate (presumably from the phloem) of the fruits of three species of the Cucurbitaceae, namely vegetable marrow (Cucurbita pepo), melon (Cucumis melo) and cucumber (Cucumis sativus). They are all strongly inhibited in their activities by chitin oligosaccharides, but only weakly by N-acetylglucosamine. Glycopeptides from soya-bean agglutinin and fetuin are also strong inhibitors of Cucurbita pepo lectin, indicating that it interacts with internal N-acetylglucosamine residues. The lectin from Cucurbita pepo fruit was purified by affinity chromatography by using chitin oligosaccharides covalently attached to Sepharose. The lectin is not a glycoprotein, and it consists of a single polypeptide chain of about 20,000 mol.wt. It is a major protein (18% of the total) of the phloem exudate and it is postulated that it may have an anti-parasitic function.

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