KONE, D. | bioRxiv Science

bioRxiv2023

Prevalence of mango postharvest Stem-end rot disease in Cote d'Ivoire and identification of fungal pathogens associated

The Stem-end rot (SER) postharvest disease of mango (Mangifera indica L.) fruits is a significant economic threat to mango production. If suitable conditions are not maintained, it can lead to losses of up to 100 %. Despite its importance, very little information is known about this disease in Cote dIvoire. This research aimed determining the incidence and severity of SER in mango orchards, assess how preharvest climate parameters affect the disease and determine the pathogenic fungi associated with SER. Therefore, mango SER was evaluated on 1500 mango fruits collected from 15 orchards.in Boundiali, Ferkessedougou, Korhogo, Odienne, and Sinematiali departments. Mango SER incidence ranged from 10 % to 30 %, while severity ranged from 5 % to 20 %. No significant differences in these parameters were observed between the different departments (P>0.05). The study also revealed a low correlation between SER disease incidence and mean air temperature (r=0.36) and minimum air temperature (r=0.26) data, indicating that preharvest weather conditions may have a marginal impact on mango SER disease intensity in the postharvest phase. Pathogenic fungi associated with SER were isolated and identified using morphological characteristics and multilocus sequence analysis of the rDNA internal transcribed spacer (ITS) region and the translation elongation factor 1-alpha (tef1-). We identified various fungal species associated with mango SER disease, with Lasiodiplodia species (74%) being the most prevalent (including Lasiodiplodia theobromae, L. euphorbicola, and L. caatinguensis), followed by Colletotrichum gloeosporioides, Curvularia pseudobrachyspora, Diaporthe endophytica and Fusarium mangiferae. However, only Lasiodiplodia species and Diaporthe endophytica induced SER symptoms. This study was the first ever evaluation of mango SER disease and associated fungal pathogens identification in Cote dIvoire. This result will assist researchers in developing a control method for mango SER.

plant biology↗

bioRxiv2021

A panel of single nucleotide polymorphism (SNP) markers identifies potential duplicates in cassava (Manihot esculenta Crantz) varieties from Cote dIvoire

Accurate identification of varieties is paramount to optimizing efficiencies in the management and conservation of genetic resources. A relatively inexpensive, rapid methodology is required to identify putative duplicates from any collection, when morphological traits give insufficient discrimination. Here we select a panel of 36 SNPs, visualized using the Kompetitive Allele-specific PCR (KASP) system. We used a panel of 95 cassava genotypes from Cote dIvoire to identify varieties that are not duplicates and few potential duplicates which could be put forward for further verification. The genetic variability and population structure of the germplasm is also described. 36 SNPs were polymorphic across the panel of 95 varieties with polymorphic information contents ranging from 0.23 to 0.37. Using these SNPs, we were able to identify 66 unique genotypes from the panel of 95 genotypes, discriminate three sets of known duplicates and identify 11 sets of unknown putative duplicates which can be subjected to further verification using higher density genotyping. As expected in an outcrossing species, both expected heterozygosity (0.46) and observed heterozygosity (0.48) were high with an analysis of molecular variance (AMOVA) indicating that the majority of variation was within individuals. Three statistical approaches i.e., hierarchical ascending clustering, Bayesian analysis and discriminant analysis of principal components were used and all revealed low genetic differentiation between sub-populations, a conclusion that was supported by the low value of the fixation index (0.05). This panel of SNPs can be used to enhance cost-effectiveness and efficiency of germplasm conservation and enhance quality control at various stages in the breeding process through varietal tracking.

plant biology↗