Identification and Characterization of Diaporthe spp. Associated with Twig Cankers and Shoot Blight of Almonds in Spain

Abstract

Two hundred and twenty-five Diaporthe isolates were collected from 2005 to 2019 in almond orchards showing twig cankers and shoot blight symptoms in five different regions across Spain. Multilocus DNA sequence analysis with five loci (ITS, tub, tef-1α, cal and his), allowed the identification of four known Diaporthe species, namely: D. amygdali, D. eres, D. foeniculina and D. phaseolorum. Moreover, a novel phylogenetic species, D. mediterranea, was described. Diaporthe amygdali was the most prevalent species, due to the largest number of isolates (85.3%) obtained from all sampled regions. The second most frequent species was D. foeniculina (10.2%), followed by D. mediterranea (3.6%), D. eres and D. phaseolorum, each with only one isolate. Pathogenicity tests were performed using one-year-old almond twigs cv. Vayro and representative isolates of the different species. Except for D. foeniculina and D. phaseolorum, all Diaporthe species were able to cause lesions significantly different from those developed on the uninoculated controls. Diaporthe mediterranea caused the most severe symptoms. These results confirm D. amygdali as a key pathogen of almonds in Spain. Moreover, the new species, D. mediterranea, should also be considered as a potential important causal agent of twig cankers and shoot blight on this crop.

Bioactive Secondary Metabolites of the Genus Diaporthe and Anamorph Phomopsis from Terrestrial and Marine Habitats and Endophytes: 2010–2019

“…Due to the importance of this genus as plant pathogens, the classification of Diaporthe has been discussed by many researchers. Since Diaporthe was cited earlier and represents most of the species described in nature, more mycologists suggest that the use of Diaporthe as a generic name have more priority and is more suitable for the current study of this fungal group [ 11 , 12 , 13 ]. In recent years, the previous classification methods based on morphological characteristics are no longer applicable to the genus Diaporthe and advanced molecular techniques will replace them to solve the classification problem of Diaporthe [ 13 , 14 ].…”

Identification and Characterization of Fungal Pathogens Causing Trunk and Branch Cankers of Almond Trees in Morocco

“…Other studies conducted on almond trees confirm that Lasiodiplodia theobromae is an important pathogen associated with branch cankers as well [19]. Moreover, in other studies, different species of Diaporthaceae (Phomopsis) were reported on Prunus trees, especially on almonds, e.g., D. eres in Portugal [26], D. foeniculina in Italy [27], and D. phaseolorum in Spain [28]. D. amygdali has been documented as the main causal agent of woody canker diseases and showed symptoms of shoot blight and twig canker associated with Punus trees [26].…”

Characteristics of Phomopsis juglandina (Sacc.) Hohn. Associated with Dieback of Walnut in the Climatic Conditions of Southern Romania

“…The fractures of the anamorph were differentiated under the periderm, at first submerged in the tissues, becoming eruptive and visible with the naked eye [34,35]. Despite the careful examination of numerous samples, from different places or taken throughout the year, we were unable to identify a teleomorph (Diaporthe) that could have been associated with the imperfect form of the pathogen [36].…”

“…The identification of these necrotrophs is difficult to achieve due to their similar symptoms on the affected branches. However, applied research at the structural, ultrastructural and pathogenic levels in correlation with detailed monitoring of environmental factors [38] is of major importance for the correct diagnosis of these spheropsidal fungi [36]. Problems related to the management of walnut cancer induced by various secondary pathogens have been presented in [39].…”