Identification and molecular dissection of broad-spectrum recessive resistance genes to plant viruses

ABSTRACT Corynebacterium jeikeium is an opportunistic pathogen primarily of immunocompromised (neutropenic) patients. Broad-spectrum resistance to antimicrobial agents is a common feature of C. jeikeium clinical isolates. We studied the profiles of susceptibility of 20 clinical strains of C. jeikeium to a range of antimicrobial agents. The strains were separated into two groups depending on the susceptibility to erythromycin (ERY), with one group (17 strains) representing resistant organisms (MIC > 128 μg/ml) and the second group (3 strains) representing susceptible organisms (MIC ≤ 0.25 μg/ml). The ERY resistance crossed to other members of the macrolide-lincosamide-streptogramin B (MLSb) group. Furthermore, this resistance was inducible with MLSb agents but not non-MLSb agents. Expression of ERY resistance was linked to the presence of an allele of the class X erm genes,erm(X)cj, with >93% identity to other ermgenes of this class. Our evidence indicates that erm(X)cj is integrated within the chromosome, which contrasts with previous reports for the plasmid-associated erm(X) genes found inC. diphtheriae and C. xerosis. In 40% ofC. jeikeium strains, erm(X)cj is present within the transposon, Tn5432. However, in the remaining strains, the components of Tn5432 (i.e., the erm and transposase genes) have separated within the chromosome. The rearrangement of Tn5432 leads to the possibility that the other drug resistance genes have become included in a new composite transposon bound by the IS1249 elements.

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Identification of Broad Spectrum Blast Resistance Genes for North-East and Eastern India using Standard International Blast Differential

International Journal of Current Microbiology and Applied Sciences ◽

10.20546/ijcmas.2019.804.308 ◽

2019 ◽

Vol 8 (04) ◽

pp. 2639-2648

Author(s):

Shamshad Alam ◽

Jahangir Imam ◽

Dipankar Maiti ◽

N.P. Mandal ◽

Chandeshwar Prasad ◽

...

Keyword(s):

Resistance Genes ◽

Broad Spectrum ◽

Blast Resistance ◽

Eastern India ◽

North East ◽

Blast Resistance Genes

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Race structure of cowpea witchweed (Striga gesnerioides) in West Africa and its implications for Striga resistance breeding of cowpea

Weed Science ◽

10.1017/wsc.2020.3 ◽

2020 ◽

Vol 68 (2) ◽

pp. 125-133 ◽

Cited By ~ 1

Author(s):

Erik W. Ohlson ◽

Michael P. Timko

Keyword(s):

West Africa ◽

Resistance Genes ◽

Broad Spectrum ◽

Genetic Relatedness ◽

Durable Resistance ◽

Resistance Breeding ◽

Differential Resistance ◽

African Countries ◽

Sources Of Resistance ◽

Striga Gesnerioides

AbstractCowpea witchweed [Striga gesnerioides (Willd.) Vatke] is a primary constraint of cowpea [Vigna unguiculata (L.) Walp.] production in West Africa. Previously, seven S. gesnerioides races were classified based upon host specificity and genotypic profiling. Because race number and distribution are dynamic systems influenced by gene flow, genetic drift, and natural selection, a thorough investigation of S. gesnerioides diversity and the effectiveness of known sources of resistance in cowpea is needed to develop varieties with durable and broad-spectrum Striga resistance. In this study, we screened seven cowpea lines against 58 unique S. gesnerioides populations collected from across nine West African countries. Individuals from 10 S. gesnerioides populations were genotyped with simple sequence repeat (SSR) markers. We identified six races of S. gesnerioides based on their parasitism of the seven cowpea lines with known differential resistance genotypes. No cowpea line was resistant to all 58 Striga populations and none of the Striga populations were able to overcome the resistance of all seven lines. A novel race, SG6, of the parasite collected from Kudu, Nigeria, was found to overcome more cowpea resistance genes than any previously reported race. SSR analysis indicates that Striga populations are highly differentiated and genetic relatedness generally corresponds with geographic proximity rather than their host compatibility. Due to the dearth of broad-spectrum resistance found among Striga-resistant cowpea lines, there exists a need to stack multiple Striga resistance genes in order to confer broad-spectrum and durable resistance.

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Viruses of New Zealand pasture grasses and legumes: a review

Crop and Pasture Science ◽

10.1071/cp14017 ◽

2014 ◽

Vol 65 (9) ◽

pp. 841 ◽

Cited By ~ 8

Author(s):

P. L. Guy

Keyword(s):

New Zealand ◽

Mosaic Virus ◽

Resistance Genes ◽

Barley Yellow Dwarf Virus ◽

Cropping Systems ◽

Alfalfa Mosaic Virus ◽

Plant Viruses ◽

Future Research ◽

Pasture Grasses ◽

Yellow Dwarf Virus

This article reviews knowledge of 23 plant viruses infecting pasture grasses and legumes in New Zealand. The incidence, ecology and impact of each virus and prospects for control using natural or artificial resistance genes or by vector control is discussed. The most prevalent viruses are Alfalfa mosaic virus and White clover mosaic virus in pasture legumes and Cocksfoot mottle virus, Ryegrass mosaic virus and Barley yellow dwarf virus in pasture grasses. Lucerne Australian latent virus is restricted to the North Island and Red clover necrotic mosaic virus is largely restricted to the South Island. These patterns are likely to be dynamic with ongoing changes in weather patterns, land use, the spread of insect vectors and the continuing introduction of viruses and vectors. The existing and potential threats to 12 pasture species are tabulated and the knowledge gaps for each species highlighted. Control of vectors including aphids, eriophyid mites and soil-borne fungi is probably not economic per se but could be an additional benefit of integrated pest management in pasture and cropping systems. The most cost-effective and practical preventative measures are likely to be the use of virus-tested seed to establish new pastures and the incorporation of resistance genes by conventional breeding or by genetic engineering. Finally, recommendations are made for future research for New Zealand, which is also relevant to other temperate regions of the world.

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