A Genome-Wide Association Study of Nigerien and Senegalese Sorghum Germplasm of Exserohilum turcicum, the Causal Agent of Leaf Blight.

In Senegal, sorghum ranks third after millet and maize among dryland cereal production and plays a critical role in the daily lives of millions of inhabitants. Yet, the crop's productivity and profitability are hampered by biotic stresses, including Exserohilum turcicum, causing leaf blight. A total of 101 sorghum accessions collected from Niger and Senegal, SC748-5 and BTx623, were evaluated in three different environments (Kaymor, Kolda, and Ndiaganiao) in Senegal for their reactions against the leaf blight pathogen. The results showed that 11 out of the 101 accessions evaluated exhibited 100% incidence, and the overall mean incidence was 88.4%. Accession N15 had the lowest incidence of 50%. The overall mean severity was 31.6%, while accessions N15, N43, N38, N46, N30, N28, and N23 from Niger recorded the lowest severity levels, ranging from 15.5% to 25.5%. Accession N15 exhibited both low leaf blight incidence and severity, indicating that it may possess genes for resistance to E. turcicum. Also, the accessions evaluated in this study were sequenced. A GWAS identified six novel single-nucleotide polymorphisms (SNPs) associated with an average leaf blight incidence rate. The candidate genes were found in chromosomes 2, 3, 5, 8, and 9. Except for SNP locus S05_48064154, all five SNPs associated with the leaf blight incidence rate were associated with the plant defense and stress responses. In conclusion, the candidate genes identified could offer additional options for enhancing plant resistance against E. turcicum through plant breeding or gene editing.

Inoculation and Screening Methods for Major Sorghum Diseases Caused by Fungal Pathogens: Claviceps africana, Colletotrichum sublineola, Sporisorium reilianum, Peronosclerospora sorghi and Macrophomina phaseolina.

Sorghum is the fifth most important crop globally. Researching interactions between sorghum and fungal pathogens is essential to further elucidate plant defense mechanisms to biotic stress, which allows breeders to employ genetic resistance to disease. A variety of creative and useful inoculation and screening methods have been developed by sorghum pathologists to study major fungal diseases. As inoculation and screening methods can be keys for successfully conducting experiments, it is necessary to summarize the techniques developed by this research community. Among many fungal pathogens of sorghum, here we summarize inoculation and screening methods for five important fungal pathogens of sorghum: Claviceps africana, Colletotrichum sublineola, Sporisorium reilianum, Peronosclerospora sorghi and Macrophomina phaseolina. The methods described within will be useful for researchers who are interested in exploring sorghum-fungal pathogen interactions. Finally, we discuss the latest biotechnologies and methods for studying plant-fungal pathogen interactions and their applicability to sorghum pathology.

A Genome-Wide Association Study of Senegalese Sorghum Seedlings Responding to Pathotype 5 of Sporisorium reilianum.

Sporisorium reilianum is a fungal pathogen that causes head smut in sorghum. In addition to pathotypes (P) 1-4, P5 and P6 were identified recently. In this study, seedlings of Senegalese sorghum, comprising 163 accessions, were evaluated for response to Sporisorium reilianum. Teliospores of pathotype P5 of the pathogen in dilute agar were pipetted onto seedling shoots while still in soil, and inoculated seedlings were submerged under water at 4 days post-inoculation. Signs of infection (noticeable spots) on the first leaf were checked daily up to 6 days post submergence. A genome-wide association study (GWAS) was conducted using 193,727 single-nucleotide polymorphisms (SNPs) throughout the genome based on two types of phenotypic data: whether noticeable spots were shown or not and the average time for an observation of the spots across 163 accessions. When mapped back to the reference sorghum genome, most of the top candidate SNP loci were associated with plant defense or plant stress response-related genes. The identified SNP loci were associated with spot appearance in sorghum seedlings under flooding following inoculation with P5 of Sporisorium reilianum.

Genome-wide association study of Senegalese sorghum seedlings responding to a Texas isolate of Colletotrichum sublineola.

Colletotrichum sublineola is a destructive fungal pathogen that causes anthracnose in sorghum. Senegalese sorghum germplasm is currently being considered as an option of sources for genetic resistance. In a recent study, Senegalese sorghum accessions were evaluated for response to a mixture of Texas isolates of C. sublineola at the 8-leaf stage in the greenhouse. As a comparison, 159 Senegalese sorghum accessions at the 1-leaf developmental stage were evaluated against a single Texas isolate of C. sublineola (FSP53) using an excised-leaf assay. A genome-wide association study (GWAS) was conducted based on the phenotypic data acquired to discover genetic variation associated with response to C. sublineola using 193,727 single nucleotide polymorphisms (SNPs) throughout the genome. Sorghum seedlings tended to be more resistant when compared with sorghum plants inoculated at the 8-leaf stage in the greenhouse in previous experiments. Based on the highest score evaluated in the 1-leaf developmental stage excised leaf assay for each accession, 16 accessions were labeled as susceptible. GWAS identified the SNP locus S01_72868925 that is associated with protein kinase domain // Leucine rich repeat N-terminal domain at a level of confidence that surpassed Bonferroni correction. Along with the SNP locus S01_72868925, other top SNP loci were also associated with genes that are known to play critical roles in plant defense or plant stress responses.

Human cytomegalovirus and isocitrate dehydrogenase status in glioma: association and prognosis value in Moroccan population.

Introduction: Human cytomegalovirus (HCMV) and isocitrate dehydrogenase (IDH) have been separately associated to gliomas. IDH is a molecular marker considered in the histo-molecular classification of gliomas as well as in their management and prognosis. However, even if oncomodulatory properties were attributed to HCMV, its association to gliomas remains a controversy. Most of the studies that investigated this association used the histological classification of gliomas; nevertheless, in 2016, the World Health Organization recommended the introduction of molecular characteristics to refine this classification. The aims of this study were to determine the prevalence of HCMV in glioma patients, the association between HCMV and IDH with gliomas and subsequently their associations with survival of patients in a Moroccan cohort. Methods: A series of 102 gliomas and 32 controls were analyzed by nested PCR (nPCR) to determine the HCMV status. PCR and sequencing were used to determine the IDH subtypes in tumors samples. IDH mutation and HCMV status were correlated to the characteristics of the tumors using SPSS, whereas the survival curves were obtained by the Kaplan-Meier method and the log rank test. Results: HCMV shows significant association with gliomas with a detection rate of 30.4% and no case in the control group. The IDH mutation was identified in 40.9-50% of grade II-III gliomas and in 10.9% of grade IV gliomas. A significant association was obtained between survival in patients with glioblastomas and IDH/HCMV status. Glioblastoma patients with HCMV+ and IDHwt had a poor prognostic. Conclusions: HCMV was detected exclusively in tumor cases and was significantly associated with poor prognosis in patients with gliomas and particularly with glioblastomas. The worst overall survival was significantly seen in patients with gliomas HCMV+/IDHwt. So, it will be of interest to consider HCMV and IDH status in gliomas management strategies.