Combined Metabarcoding and Multi-locus approach for Genetic characterization of Colletotrichum species associated with common walnut (Juglans regia) anthracnose in France

Abstract

Juglans regia (walnut) is a species belonging to the family Juglandaceae. Broadly spread in diverse temperate and subtropical regions, walnut is primarily cultivated for its nuts. In France, Colletotrichum sp. on walnut was detected for the first time in 2007; in 2011 the disease led to 50–70% losses in nut production. A combined approach of metabarcoding analysis and multi-locus genetic characterization of isolated strains has been used for taxonomic designation and to study the genetic variability of this pathogen in France. Evidence indicates that four Colletotrichum species are associated with walnut in France: 3 belong to the C. acutatum species complex and 1 to the C. gloeosporioides species complex. Results also show that C. godetiae is the most abundant species followed by C. fioriniae; while C. nymphaeae and another Colletotrichum sp. belonging to the C. gloeosporioides complex are found rarely. Representative isolates of detected species were also used to confirm pathogenicity on walnut fruits. The results show a high variability of lesion’s dimensions among isolates tested. This study highlights the genetic and pathogenic heterogeneity of Colletotrichum species associated with walnut anthracnose in France providing useful information for targeted treatments or selection of resistant cultivars, in order to better control the disease.

Genome-wide identification and characterization of long non-coding RNAs conferring resistance to Colletotrichum gloeosporioides in walnut (Juglans regia)

“…In this study, we investigated the role of lncRNAs in the resistance of walnut fruit bracts to anthracnose based on sequence analyses. Walnut anthracnose is caused by C. gloeosporioides , which completes its infection process as a hemibiotroph [ 10 , 38 ]. First, conidia germinate to generate appressoria, which produce invasion pegs that initiate the infection into susceptible plants.…”

Genome-wide identification and characterization of long non-coding RNAs conferring resistance to Colletotrichum gloeosporioides in walnut (Juglans regia)

“…tomato DC3000 by promoting PR1 expression [40]. In tomato, lncRNA23468 functions as a ceRNA that modulates NBS-LRR gene expression by mimicking the target of miR482b, thereby increasing the resistance to P. infestans [41].Walnut anthracnose has been responsible for the premature fruit drop and yield losses that have adversely affected walnut production in China [7]. In this study, we investigated the role of lncRNAs in the resistance of walnut fruit bracts to anthracnose based on sequence analyses.…”

“…Simultaneously, plants have evolved R genes that recognize these effectors and function through highly speci c interactions between effectors and their corresponding nucleotide-bindingsite and leucine-rich repeat (NB-LRR) class receptors [60]. In tomato, lncRNA23468 reportedly increases the expression of the NBS-LRR target genes (encoding R proteins), resulting in enhanced resistance to P.infestans [41]. In the current study, we detected 10 R genes among the target genes of 96 hub lncRNAs.…”

Molecular Detection of the Seed-Borne Pathogen Colletotrichum lupini Targeting the Hyper-Variable IGS Region of the Ribosomal Cluster

“…The cluster contains rRNA genes (18S, 5.8S, and 28S) separated by two internal transcribed spacers (ITS1 and ITS2) and one intergenic spacer (IGS) [25]. Recent phylogenetic studies have highlighted that the ITS region of the rDNA does not have sufficient variability to perform a correct taxonomic designation [26] or to develop specific primers for most Colletotrichum species. For this reason, other highly polymorphic single copy genes have been proposed to develop specific detection methods for Colletotrichum spp.…”