Protease Production During Pathogenesis of Bacterial Leaf Spot of Alfalfa and by Xanthomonas alfalfae In Vitro

During 1995 and 1996, bacterial leaf spots severely damaged fields of kale, spinach mustard, and turnip in Oklahoma. Symptoms were small, brown, necrotic spots with irregular edges surrounded by chlorotic halos. Lesion margins were often water-soaked on the abaxial surface. The spots enlarged and coalesced, causing extensive leaf yellowing and necrosis. Nineteen strains of a fluorescent Pseudomonas spp. were isolated from symptomatic plants. LOPAT tests and carbon source oxidation using Biolog GN MicroPlates were used to classify the strains as P. syringae. Cluster analysis of carbon source oxidation profiles for the local strains and selected reference strains of P. syringae pv. maculicola and pv. tomato produced one group with 79.5% similarity. In spray inoculations, all local strains caused chlorotic or water-soaked lesions on collards, kale, cauliflower, and tomato. A few local strains caused necrotic lesions on mustard. Most local strains caused one of the three lesion types on turnip and spinach mustard. Reference strains of P. syringae pv. maculicola caused similar symptoms. All but three of the local strains produced coronatine in vitro. The local strains were thus classified as P. syringae pv. maculicola, the cause of bacterial leaf spot of crucifers. Two distinct groups of P. syringaepv. maculicola were identified by repetitive sequence-based polymerase chain reaction (rep-PCR) with both REP and BOXA1R primers. Three subgroups within each group were further identified using the BOXA1R primer. Except for two strains of P. syringae pv. tomato which were pathogenic on crucifers, the pathovars maculicola and tomato had different genetic fingerprints. The pathogen was recovered from seven of ten fields sampled during 1994 to 1996. In five of the fields with P. syringae pv. maculicola, pathovars of Xanthomonas campestris were also isolated from lesions forming a bacterial disease complex. This is the first report of bacterial leaf spot caused by P. syringaepv. maculicola on leafy crucifers in Oklahoma.

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Sugar maple autumn-shed leaf extract: a potential antibacterial agent for the management of lettuce bacterial leaf spot (Xanthomonas campestris pv. vitians) and varnish spot (Pseudomonas cichorii)

Canadian Journal of Plant Science ◽

10.1139/cjps-2019-0040 ◽

2020 ◽

Vol 100 (1) ◽

pp. 78-85 ◽

Cited By ~ 2

Author(s):

M. Delisle-Houde ◽

R.J. Tweddell

Keyword(s):

Leaf Spot ◽

Xanthomonas Campestris ◽

Sugar Maple ◽

Foliar Application ◽

Antibacterial Activities ◽

Northern Red Oak ◽

Bacterial Leaf Spot ◽

Pseudomonas Cichorii ◽

Bacterial Diseases

Different extracts prepared from wastes (barks, branches, needles, or leaves) of different trees (grey alder, balsam fir, American larch, red maple, sugar maple, white spruce, black spruce, jack pine, white pine, quaking aspen, sweet cherry, and northern red oak) were investigated for their potential use as antibacterial agents for the management of lettuce varnish spot and bacterial leaf spot caused by Pseudomonas cichorii (Swingle) Stapp and Xanthomonas campestris pv. vitians (Brown) Dye, respectively. Extracts were first screened for their antibacterial activities against P. cichorii and X. campestris pv. vitians using the in vitro disk diffusion assay. Based on the diameter of the inhibition zone, ethanol (95%) extract prepared from sugar maple autumn-shed leaves (SMASL) and aqueous ethanol (50%, v/v) extracts prepared from SMASL and from sugar maple green leaves showed the strongest antibacterial activities. Ethanol (95%) SMASL extract was further investigated for its efficacy to manage bacterial diseases when applied on lettuce plants grown in the greenhouse. Foliar application of ethanol (95%) SMASL extract at a concentration of 3.2 g L−1 was shown to significantly (P ≤ 0.05) reduce bacterial leaf spot severity compared with the control without causing phytotoxicity symptoms that could prevent the commercial marketing of the lettuce. Ethanol (95%) SMASL extract (1.6 and 3.2 g L−1) was also shown to significantly reduce varnish spot severity in one experiment out of two. This study identifies for the first time the possibility of exploiting SMASL to manage bacterial diseases affecting horticultural crops.

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In Vitro Nutrition of Xanthomonas alfalfae, Causal Organism of Bacterial Leaf Spot of Alfalfa)

Journal of Phytopathology ◽

10.1111/j.1439-0434.1972.tb02593.x ◽

1972 ◽

Vol 75 (1) ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

M. N. Reddy ◽

D. L. Stuteville ◽

E. L. Sorensen

Keyword(s):

Leaf Spot ◽

Bacterial Leaf Spot ◽

Causal Organism

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In vitro efficacy antibiotics against Bacterial leaf spot of chilli caused by Xanthomonas axonopodis pv. vesicatoria

International Journal of Chemical Studies ◽

10.22271/chemi.2020.v8.i6r.10930 ◽

2020 ◽

Vol 8 (6) ◽

pp. 1237-1239

Author(s):

SM Chapke ◽

DS Bharti ◽

PL Sontakke ◽

MG Patil ◽

DN Dhutraj

Keyword(s):

Leaf Spot ◽

Bacterial Leaf Spot ◽

Xanthomonas Axonopodis

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Incorporation of Engineered Nanoparticles of Biochar and Fly Ash Against Bacterial Leaf Spot of Pepper

10.21203/rs.3.rs-877890/v1 ◽

2021 ◽

Author(s):

Muhammad Danish Ali ◽

Zill-e-Huma Aftab ◽

Adnan Akhter ◽

Farzana Majid ◽

Iffat Siddiqui ◽

...

Keyword(s):

Fly Ash ◽

Leaf Spot ◽

Xanthomonas Campestris ◽

Plant Biomass ◽

Plant Defence ◽

Engineered Nanoparticles ◽

Pepper Plant ◽

Bacterial Leaf Spot ◽

Main Challenge

Abstract In agriculture, the search for higher net profit is the main challenge in the economy of the producers and nano biochar attracts increasing interest in recent years due to its unique environmental behaviour and increasing the productivity of plants by inducing resistance against phyto-pathogens. The effect of rice straw biochar and fly ash nanoparticles (RSBNPs and FNPs, respectively) in combination with compost soil on bacterial leaf spot of pepper caused by Xanthomonas campestris pv. vesicatoria was investigated both in vitro and in vivo. The application of nanoparticles as soil amendment significantly improved the chili pepper plant growth. However, RSBNPs were more effective in enhancing the above and belowground plant biomass production. Moreover, both RSBNPs and FNPs, significantly reduced (30.5 and 22.5 %, respectively), while RSBNPs had shown in vitro growth inhibition of X. campestris pv. vesicatoria by more than 50%. The X-ray diffractometry of RSBNPs and FNPs highlighted the unique composition of nano forms which possibly contributed in enhancing the plant defence against invading X. campestris pv. vesicatoria. On the basis of our findings, it is suggested that biochar and fly ash nanoparticles can be used for reclaiming the problem soil and enhance the crop productivity depending upon the nature of soil and the pathosystem under investigation.

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