Recombination events are frequently inferred from the increasing number of sequenced viral genomes, but their impact on natural viral populations has rarely been evidenced. TYLCV-IS76 is a recombinant (Begomovirus,Geminiviridae) between the Israel strain of tomato yellow leaf curl virus (TYLCV-IL) and the Spanish strain of tomato yellow leaf curl Sardinia virus (TYLCSV-ES) that was generated most probably in the late 1990s in southern Morocco (Souss). Its emergence in the 2000s coincided with the increasing use of resistant tomato cultivars bearing the Ty-1 gene, and led eventually to the entire displacement of both parental viruses in the Souss. Here, we provide compelling evidence that this viral population shift was associated with selection of TYLCV-IS76 viruses in tomato plants and particularly in Ty-1-bearing cultivars. Real-time quantitative PCR (qPCR) monitoring revealed that TYLCV-IS76 DNA accumulation in Ty-1-bearing plants was significantly higher than that of representatives of the parental virus species in single infection or competition assays. This advantage of the recombinant in Ty-1-bearing plants was not associated with a fitness cost in a susceptible, nearly isogenic, cultivar. In competition assays in the resistant cultivar, the DNA accumulation of the TYLCV-IL clone - the parent less affected by the Ty-1 gene in single infection - dropped below the qPCR detection level at 120 days post-infection (p.i.) and below the whitefly vector (Bemisia tabaci) transmissibility level at 60 days p.i. The molecular basis of the selective advantage of TYLCV-IS76 is discussed in relation to its non-canonical recombination pattern, and the RNA-dependent RNA polymerase encoded by the Ty-1 gene.

Recombinant viruses are increasingly being reported but the dynamics of their emergence is rarely documented. A new recombinant Tomato yellow leaf curl virus (TYLCV-IS76) was detected for the first time in 2010 in Southern Morocco (Souss). An original diagnostic tool was needed to fit its unusual recombination profile. Although IS76 was detected following the appearance of Tylc symptoms on tolerant tomato plants, symptoms could not be associated to IS76 or to a synergy with criniviruses. According to infection profiles of Tylc-associated viruses determined on 879 plant samples collected between 1998 and 2014 and a Bayesian inference applied to genomic sequences of representatives of TYLCV, IS76 emerged in Southern Morocco at the end of the 1990s, replaced the parental viruses between 2004 and 2012 in Souss and is spreading towards the North of Morocco. The emergence of IS76 coincides with the increasing use of tolerant cultivars in the 2000s.

The Mediterranean fruit fly, Ceratitis capitata Wiedemann, is a deleterious pest worldwide affecting fruit production. The entomopathogenic nematodes (EPNs) are a potential biocontrol agent that could be effectively used to control this Mediterranean fruit fly. In this study, five EPN strains reported from different fields in Morocco were evaluated for their efficacy against C. capitata. In laboratory assays, Steinernema feltiae-SF-MOR9, S. feltiae-SF-MOR10 and Heterorhabditis bacteriophora-HB-MOR7 strains showed significantly higher infectivity and penetration rates when compared to the other strains. S. feltiae-SF-MOR9 caused the highest larval mortality rate (80%) at 50 infective juveniles (IJs) cm−2. However, additional results showed that both S. feltiae strains were significantly effective in controlling C. capitata larvae in apricot (Prunus armeniaca) fruits on soil surface with high mortality rate at 50 and 100 IJs cm−2. Different soil textures and moisture levels resulted in a significant variation in EPN strain virulence against C. capitata. Sandy clay loam soil in combination with 50 IJs cm−2 of S. feltiae (SF-MOR9 or SF-MOR10) caused a higher mortality rate of C. capitata larvae. Furthermore, applying these EPN strains at 50–100 IJs cm−2 in combination with 10–15% moisture level showed optimal results against C. capitata larvae. Therefore, those two Moroccan EPN strains could be used as promising eco-friendly biological agents against C. capitata.

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The main objective of this study was to evaluate the ability of both antagonistic bacteria Bacillus amyloliquefaciens (SF14) and Alcaligenes faecalis (ACBC1) used in combination with salicylic acid (SA) to effectively control brown rot disease caused by Monilinia fructigena. Four concentrations of salicylic acid (0.5%, 2%, 3.5%, and 5%) were tested under in vitro and in vivo conditions. Furthermore, the impact of biological treatments on nectarine fruit parameters’ quality, in particular, weight loss, titratable acidity, and soluble solids content, was evaluated. Regardless of the bacterium, the results indicated that all combined treatments displayed a strong inhibitory effect on the mycelial growth of M. fructigena and disease severity. Interestingly, all SA concentrations significantly improved the biocontrol activity of each antagonist. The mycelial growth inhibition rate ranged from 9.79% to 88.02% with the highest reduction rate recorded for bacterial antagonists in combination with SA at both concentrations of 0.5% and 3.5%. The in vivo results confirmed the in vitro results with a disease severity varying from 0.00% to 51.91%. A significant biocontrol improvement was obtained with both antagonistic bacteria when used in combination with SA at concentrations of 0.5% and 2%. The lowest disease severity observed with ACBC1 compared with SF14 is likely due to a rapid adaptation and increase of antagonistic bacteria population in wounded sites. The impact of all biological treatments revealed moderate significant changes in the fruit quality parameters with weight loss for several treatments. These results suggest that the improved disease control of both antagonistic bacteria was more likely directly linked to both the inhibitory effects of SA on pathogen growth and induced fruit resistance.