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Among the various diseases occurring in the pecan tree crop, anthracnose, caused by species of the genus Colletotrichum, stands out. Biocontrol using Trichodermapresents as a promising measure to be used in disease control because it has a broad spectrum of action on phytopathogens, enables the activation of the defense system, and the promotion of plant growth, contributes to environmental sustainability and food security. This study aimed to investigate the in vitroantagonistic action of Trichodermaspecies on Colletotrichum, the etiological agent of anthracnose in pecan. The dual-culture assay and the inhibition test by volatile metabolites were performed with five species of Trichoderma (T. harzianum, T. koningiopsis, T. asperellum, T. tomentosum,and T. virens). Mycelial growth was evaluated daily until the seventh day. In the dual-culture assay, all species showed antagonist potential, inhibiting the mycelial growth of the pathogens from the third day onward. Trichoderma virensand T. tomentosumshowed greater antagonist potential and stood out in the volatile metabolites.

ABSTRACTCarya illinoinensis(pecan) is a fruit crop native to Mexico and the USA and cultivated across the world. Despite the advances of the molecular markers’ technologies and their use in genetic studies of diversity and breeding, studies with this species only reticently accompanied this progress. Here we review the studies using molecular markers, the gaps, and the perspectives concerning these technologies in pecaniculture. The selection of plants more adapted to the particular conditions where the species is cultivated and the obligatory outcrossing mode of reproduction lead the species to generate several new genetic combinations. Molecular markers were employed to assess this diversity, using PCR-based markers and sequencing-based technologies. Genetic diversity was characterised in natural populations and collections of pecan germplasm. Markers putatively linked to traits of interest were reported and the genome sequencing technology provided insights into the evolution of the species. The outcomes of these studies still have to be integrated and further exploited to reach and impact the orchards and breeding programmes. However, the scientific advances in molecular markers research and the growth of the pecan’s supply chain may drive to a scenario in which these biotechnologies will become tools regularly assisting breeders and farmers.

Repetitive genomic elements were prospected in Campomanesia xanthocarpa, aiming to characterize these elements in a non-model plant species and to develop species-specific microsatellite markers. Approximately 4.12% of the partial genome of C. xanthocarpais composed of repetitive elements, being retrotransposons the most widely represented. A total of nine polymorphic microsatellite markers were obtained: four nuclear-neutral, two nuclear EST, two plastidial and one mitochondrial. Levels of population genetic diversity of four natural populations of C. xanthocarpawere characterized using these markers. In addition, the cross-species amplification of the microsatellite markers was tested in seven species of tribe Myrteae (Myrtaceae). The characterized microsatellite markers revealed low to moderate levels of genetic diversity (expected heterozygosity range: 0.33–0.57; observed heterozygosity: 0.26–0.74 and number of alleles: 2.25–4.25). Cross-species amplification was successful for all loci, except Cxant76. These nine markers will contribute for studies on genetic diversity, gene flow, plant selection and breeding of this species, towards the conservation of natural populations, as well as its commercial use.