Principal Diseases of Major Crops in Pakistan with Reference to Genetic Resistance

Among the Brassica oilseeds, canola (Brassica napus) is the most economically significant globally. However, its production can be limited by blackleg disease, caused by the fungal pathogen Lepstosphaeria maculans. The deployment of resistance genes has been implemented as one of the key strategies to manage the disease. Genetic resistance against blackleg comes in two forms: qualitative resistance, controlled by a single, major resistance gene (R gene), and quantitative resistance (QR), controlled by numerous, small effect loci. R-gene-mediated blackleg resistance has been extensively studied, wherein several genomic regions harbouring R genes against L. maculans have been identified and three of these genes were cloned. These studies advance our understanding of the mechanism of R gene and pathogen avirulence (Avr) gene interaction. Notably, these studies revealed a more complex interaction than originally thought. Advances in genomics help unravel these complexities, providing insights into the genes and genetic factors towards improving blackleg resistance. Here, we aim to discuss the existing R-gene-mediated resistance, make a summary of candidate R genes against the disease, and emphasise the role of players involved in the pathogenicity and resistance. The comprehensive result will allow breeders to improve resistance to L. maculans, thereby increasing yield.

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The Grapevine E3 Ubiquitin Ligase VriATL156 Confers Resistance against the Downy Mildew Pathogen Plasmopara viticola

International Journal of Molecular Sciences ◽

10.3390/ijms22020940 ◽

2021 ◽

Vol 22 (2) ◽

pp. 940

Author(s):

Elodie Vandelle ◽

Pietro Ariani ◽

Alice Regaiolo ◽

Davide Danzi ◽

Arianna Lovato ◽

...

Keyword(s):

Downy Mildew ◽

Ubiquitin Ligase ◽

Control Measure ◽

Durable Resistance ◽

Genetic Resistance ◽

E3 Ubiquitin Ligase ◽

Plasmopara Viticola ◽

Vitis Vinifera L ◽

Vitis Species ◽

Vitis Riparia

Downy mildew, caused by Plasmopara viticola, is one of the most severe diseases of grapevine (Vitis vinifera L.). Genetic resistance is an effective and sustainable control strategy, but major resistance genes (encoding receptors for specific pathogen effectors) introgressed from wild Vitis species, although effective, may be non-durable because the pathogen can evolve to avoid specific recognition. Previous transcriptomic studies in the resistant species Vitis riparia highlighted the activation of signal transduction components during infection. The transfer of such components to V. vinifera might confer less specific and therefore more durable resistance. Here, we describe the generation of transgenic V. vinifera lines constitutively expressing the V. riparia E3 ubiquitin ligase gene VriATL156. Phenotypic and molecular analysis revealed that the transgenic plants were less susceptible to P. viticola than vector-only controls, confirming the role of this E3 ubiquitin ligase in the innate immune response. Two independent transgenic lines were selected for detailed analysis of the resistance phenotype by RNA-Seq and microscopy, revealing the profound reprogramming of transcription to achieve resistance that operates from the earliest stages of pathogen infection. The introduction of VriATL156 into elite grapevine cultivars could therefore provide an effective and sustainable control measure against downy mildew.

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Identification of SNPs Associated with Somatic Cell Score in Candidate Genes in Italian Holstein Friesian Bulls

Animals ◽

10.3390/ani11020366 ◽

2021 ◽

Vol 11 (2) ◽

pp. 366

Author(s):

Riccardo Moretti ◽

Dominga Soglia ◽

Stefania Chessa ◽

Stefano Sartore ◽

Raffaella Finocchiaro ◽

...

Keyword(s):

Candidate Genes ◽

Genetic Resistance ◽

Genetic Selection ◽

Significant Snps ◽

Economic Losses ◽

Genotype Distribution ◽

Inflammatory Reactions ◽

Next Generation Sequencing Technology ◽

Holstein Friesian ◽

Holstein Bulls

Mastitis is an infectious disease affecting the mammary gland, leading to inflammatory reactions and to heavy economic losses due to milk production decrease. One possible way to tackle the antimicrobial resistance issue stemming from antimicrobial therapy is to select animals with a genetic resistance to this disease. Therefore, aim of this study was to analyze the genetic variability of the SNPs found in candidate genes related to mastitis resistance in Holstein Friesian bulls. Target regions were amplified, sequenced by Next-Generation Sequencing technology on the Illumina® MiSeq, and then analyzed to find correlation with mastitis related phenotypes in 95 Italian Holstein bulls chosen with the aid of a selective genotyping approach. On a total of 557 detected mutations, 61 showed different genotype distribution in the tails of the deregressed EBVs for SCS and 15 were identified as significantly associated with the phenotype using two different approaches. The significant SNPs were identified in intergenic or intronic regions of six genes, known to be key components in the immune system (namely CXCR1, DCK, NOD2, MBL2, MBL1 and M-SAA3.2). These SNPs could be considered as candidates for a future genetic selection for mastitis resistance, although further studies are required to assess their presence in other dairy cattle breeds and their possible negative correlation with other traits.

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Updated Characterization of Races of Plasmopara halstedii and Entomopathogenic Fungi as Endophytes of Sunflower Plants in Axenic Culture

Agronomy ◽

10.3390/agronomy11020268 ◽

2021 ◽

Vol 11 (2) ◽

pp. 268

Author(s):

Pedro Miranda-Fuentes ◽

Ana B. García-Carneros ◽

Leire Molinero-Ruiz

Keyword(s):

Plant Growth ◽

Downy Mildew ◽

Entomopathogenic Fungi ◽

Genetic Resistance ◽

Axenic Culture ◽

Plasmopara Halstedii ◽

Successful Establishment ◽

Axenic Conditions ◽

Highly Virulent

The management of downy mildew (Plasmopara halstedii) in sunflower, is heavily dependent on genetic resistance, whilst entomopathogenic fungi (EF) can reduce other sunflower diseases. In this work, we characterized P. halstedii from Spain and other countries collected in the past few years. Twenty-three races were identified (the most frequent in Spain being 310, 304, 705 and 715), with an increasing proportion of highly virulent races. Five isolates from countries other than Spain overcame the resistance in RHA-340. In addition, we assessed the efficacy of five EF against downy mildew and their effects on sunflower growth in axenic conditions. None of the entomopathogens reduced disease severity, nor did they have any effect on plant growth when applied together with P. halstedii. In contrast, three EF reduced some of the plant growth variables in the absence of the pathogen. Microbiological and molecular diagnostics suggest that the axenic system and the short experimental time used in this study did not favor the successful establishment of EF in the plants or their potential biocontrol effect. Our results show a shift in P. halstedii racial patterns and suggest that soil as a growth substrate and long infection times are needed for EF effectiveness against downy mildew.

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Investigating mechanisms underlying genetic resistance to Salmon Rickettsial Syndrome in Atlantic salmon using RNA sequencing

BMC Genomics ◽

10.1186/s12864-021-07443-2 ◽

2021 ◽

Vol 22 (1) ◽

Author(s):

Carolina P. Moraleda ◽

Diego Robledo ◽

Alejandro P. Gutiérrez ◽

Jorge del-Pozo ◽

José M. Yáñez ◽

...

Keyword(s):

Atlantic Salmon ◽

Rna Sequencing ◽

Host Resistance ◽

Large Population ◽

Genetic Resistance ◽

Head Kidney ◽

Breeding Values ◽

Association Analyses ◽

Polygenic Trait ◽

Salmon Rickettsial Syndrome

Abstract Background Salmon Rickettsial Syndrome (SRS), caused by Piscirickettsia salmonis, is one of the primary causes of morbidity and mortality in Atlantic salmon aquaculture, particularly in Chile. Host resistance is a heritable trait, and functional genomic studies have highlighted genes and pathways important in the response of salmon to the bacteria. However, the functional mechanisms underpinning genetic resistance are not yet well understood. In the current study, a large population of salmon pre-smolts were challenged with P. salmonis, with mortality levels recorded and samples taken for genotyping. In parallel, head kidney and liver samples were taken from animals of the same population with high and low genomic breeding values for resistance, and used for RNA-Sequencing to compare their transcriptome profile both pre and post infection. Results A significant and moderate heritability (h2 = 0.43) was shown for the trait of binary survival. Genome-wide association analyses using 38 K imputed SNP genotypes across 2265 animals highlighted that resistance is a polygenic trait. Several thousand genes were identified as differentially expressed between controls and infected samples, and enriched pathways related to the host immune response were highlighted. In addition, several networks with significant correlation with SRS resistance breeding values were identified, suggesting their involvement in mediating genetic resistance. These included apoptosis, cytoskeletal organisation, and the inflammasome. Conclusions While resistance to SRS is a polygenic trait, this study has highlighted several relevant networks and genes that are likely to play a role in mediating genetic resistance. These genes may be future targets for functional studies, including genome editing, to further elucidate their role underpinning genetic variation in host resistance.

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First Survey of SNPs in TMEM154, TLR9, MYD88 and CCR5 Genes in Sheep Reared in Italy and their Association with Resistance to SRLVs Infection

Viruses ◽

10.3390/v13071290 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1290

Author(s):

Chiara Arcangeli ◽

Daniele Lucarelli ◽

Martina Torricelli ◽

Carla Sebastiani ◽

Marcella Ciullo ◽

...

Keyword(s):

Genetic Resistance ◽

Economic Losses ◽

Ccr5 Gene ◽

Innovative Strategy ◽

Visna Virus ◽

Starting Point ◽

Tlr9 Gene ◽

Novel Variants ◽

Serological Status

Maedi-visna virus (MVV) and caprine arthritis encephalitis virus (CAEV), referred to as small ruminant lentiviruses (SRLVs), belong to the genus Lentivirus of the Retroviridae family. SRLVs infect both sheep and goats, causing significant economic losses and animal welfare damage. Recent findings suggest an association between serological status and allelic variants of different genes such as TMEM154, TLR9, MYD88 and CCR5. The aim of this work was to investigate the role of specific polymorphisms of these genes in SRLVs infection in some sheep flocks in Italy. In addition to those already known, novel variants in the TMEM154 (P7H, I74V, I105V) gene were detected in this study. The risk of infection was determined finding an association between the serological status and polymorphisms P7H, E35K, N70I, I74V, I105V of TMEM154, R447Q, A462S and G520R in TLR9 gene, H176H* and K190K* in MYD88 genes, while no statistical association was observed for the 4-bp deletion of the CCR5 gene. Since no vaccines or treatments have been developed, a genetically based approach could be an innovative strategy to prevent and to control SRLVs infection. Our findings are an important starting point in order to define the genetic resistance profile towards SRLVs infection.

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