Occurrence and Relative Prevalence of Fungal Pathogens on Durum Wheat

An assessment of six Bulgarian and six foreign varieties of durum wheat was carried out for the occurrence of foliar diseases caused by fungal pathogens on a natural background. Field experiments were performed at two locations (Chirpan and Sofia) situated in different climatic zones of Bulgaria for six successive growing seasons (2012 ndash%253B 2017) with exception of 2015 in Chirpan. The results of this research showed that the population of foliar pathogens of durum wheat was heterogeneous and included 13 fungal species. Some differences in symptom severity and relative proportion of the pathogens among varieties and years and between locations were found. Of the leaf spotting fungi, the causal agent of tan spot (Pyrenophora tritici-repentis) was the most prevalent in both prospected areas. The fungi belonging to Septoria leaf blotch complex (Parastagonospora avenae f. sp. triticea, Pa. nodorum and Zymoseptoria tritici) and newly found species Phaeophleospora sp. were more frequently isolated from leaf samples taken in Sofia location. Monographella nivalis and Cladosporium herbarum had contribution to the leaf spotting in both surveyed locations in some of the studied years. Cochliobolus sativus occurred only occasionally. Of the three rust fungi, Puccinia striiformis f. sp. striiformis was the predominant species. The first record of yellow rust was made in 2013. It was the most common disease in both localities in 2014 and 2016 due to warmer winters, which favored the survival of YR. The race analysis performed in Global Rust Reference Center revealed the appearance and distribution of a new race (Warrior) in Bulgaria. The weather conditions were exceptionally favourable for the development of certain diseases in some years. In this relation the influence of some elements of the climate on the pathogen prevalence was discussed. Except the weather other factors like cultivar characteristics, inoculum level, soil type, and predecessor played a role in changing spectrum of phytopathogenic fungi. In common the level of fungal diseases in Sofia region was higher compared to Chirpan. The studied varieties differed in their susceptibility to fungal diseases

Morphological, Pathological, and Genetic Diversity of Colletotrichum Species Pathogens on Solanaceous Vegetable Crops in Bulgaria

Colletotrichum species are among the most devastating plant pathogens in a wide range of hosts. Their accurate identification requires a polyphasic approach, including geographical, ecological, morphological, and genetic data. Solanaceous crops are of significant economic importance for Bulgarian agriculture. Colletotrichum-associated diseases pose a serious threat to the yield and quality of production but are still largely unexplored. The aim of this study was to identify and characterize 26 pathogenic Colletotrichum isolates that threaten solanaceous crops based on morphological, pathogenic, and molecular data. DNA barcodes enabled the discrimination of three main taxonomic groups: C. acutatum, C. gloeosporioides, and C. coccodes. Three different species of acutatum complex (C. nymphaeae, C. godetiae, and C. salicis) and C. cigarro of the gloeosporioides complex were associated with fruit anthracnose in peppers and tomatoes. The C. coccodes group was divided in two clades: C. nigrum, isolated predominantly from fruits, and C. coccodes, isolated mainly from roots. Only C. salicis and C. cigarro produced sexual morphs. The species C. godetiae, C. salicis, and C. cigarro have not previously been reported in Bulgaria. Our results enrich the knowledge of the biodiversity and specific features of Colletotrichum species, which are pathogenic to solanaceous hosts, and may serve as a scientific platform for efficient disease control and resistance breeding

Morphological, Pathological and Genetic Diversity of the Colletotrichum Species, Pathogenic on Solanaceous Vegetable Crops in Bulgaria

Colletotrichum species are among the most devastating plant pathogens in a wide range of hosts. Their accurate identification requires a polyphasic approach, including geographical, ecological, morphological, and genetic data. Solanaceous crops are of significant economic importance for Bulgarian agriculture. Colletotrichum-associated diseases pose a serious threat to the yield and quality of production but are still largely unexplored. The aim of this study was to identify and characterize 26 pathogenic Colletotrichum isolates that threaten solanaceous crops based on morphological, pathogenic, and molecular data. DNA barcodes enabled the discrimination of three main taxonomic groups: C. acutatum, C. gloeosporioides, and C. coccodes. Three different species of acutatum complex (C. nymphaeae, C. godetiae, and C. salicis) and C. cigarro of the gloeosporioides complex were associated with fruit anthracnose in peppers and tomatoes. The C. coccodes group was divided in two clades: C. nigrum, isolated predominantly from fruits, and C. coccodes, isolated mainly from roots. Only C. salicis and C. cigarro produced sexual morphs. The species C. godetiae, C. salicis, and C. cigarro have not previously been reported in Bulgaria. Our results enrich the knowledge of the biodiversity and specific features of Colletotrichum species, which are pathogenic to solanaceous hosts, and may serve as a scientific platform for efficient disease control and resistance breeding

Pepper Diseases in Balkan Region

One of the most important problems affecting pepper production in the Balkan peninsula is the occurrence of common pathogens causing severe diseases and epidemics resulting in reduced and compromised yield. In the last years new pepper fungal pathogens (Phomopsis capsid and several Colletooichum spp.) were found in Bulgaria with increasingly frequency. In 20lO a SEE-ERA.NET project started combining the research efforts of 7 scientific institutions from 5 Balkan countries (Albania, Bulgalia, FYR Macedonia, Greece and Serbia)

Morphological and molecular characterization of Colletotrichum coccodes isolated from pepper cultivated in Bulgaria and Macedonia

Colletotrichum coccodes has been recognized as one of the causal agents of pepper fruit anthracnose in Bulgaria. Recently, this species has been recorded in pepper fruits in Macedonia. In Bulgaria, the fungus has also been isolated from roots of premature senescent pepper plants but in Macedonia it has not been isolated yet. The purpose of the investigation was to make comparative morphological, cultural and molecular characterization of C. coccodes isolates obtained from pepper fruits and roots in Bulgaria and Macedonia. Additionally, a technique was applied to differentiate among the C. coccodes isolates obtained from roots and other microsclerotia-producing fungi. On the host tissue, C. coccodes developed acervular conidiomata with cup-shaped fruiting bodies accompanied with dark-pigmented, unbranched, thick-walled sterile hyphae called setae. A slimy mass of hyaline, straight, unicellular, fusiform conidia appeared on nutrient media. In a short time, numerous small dark globose setose microsclerotia emerged in the colony starting from its centre and distributing proportionally throughout agar plates. Two PCR primer sets were used to sequences of the ribosomal internal transcribed spacer (ITS1 and ITS2) regions. Single products of ~450 bp and ~350 bp were amplified by the genus-specific (Cc1F1/Cc2R1) and the species-specific primers (Cc1NF1/Cc2NR1), respectively. Morphological, cultural and molecular characterization of the isolates from roots and fruits showed that root rot and fruit anthracnose of pepper were caused by one and the same causal agent determined as C. coccodes. The isolates from roots showed rapid mycelial growth, gave rise to numerous minute microsclerotia and produced conidia only on SSPA. SSPA supported significantly more mycelium growth and sporulation than all other media tested and could be recommended for production of large quantity of conidia. No pattern of genetic variation associated with the organ or geographic origin of the isolates was determined. KEY WORDS: acervuli, fungal isolates, ITS, microscleroti

Phompsis Capsici and Colletotrichum Coccoides Infecting Pepper in Macedonia

Phomopsis capsici and Colletotrichum coccodes were found on pepper fruits during a joint expedition carried out in Macedonia. The lesions caused by P. capsici often occurred together and resembled slightly those incited by C. coccodes. Phomopsis lesions could be differentiated on the basis of pliable leathery condition of the affected tissue and of pycnidium presence while C.coccodes produced lesions with regular round shape and abundant acervuli, setae and microsclerotia in colonized fruit tissue. On some fruits P. capsici caused single infection but mixed infections of Phomopsis and Colletotrichum were observed, as well, C. coccodes is a soil-borne pathogen that produces long-lasting structures (microsclerotia) in the plant debris. The development of this pathogen on pepper might contribute to the building up of inoculum in the soil which could serve as reservoir for other Solanaceae. To our knowledge, this is the first report of P. capsici and C. coccodes on pepper in Macedonia

Gnomonia Leptostyla (Fr.) Ces. et de Not. causer of walnut anthracnose in the east part of the Republic of Macedonia

The anthracnose is one of the most destructive diseases of walnut(Juglans regia L.) worldwide. The causal agent is an ascomycetous fungus(Gnomonia leptostyla (Fr.) Ces. et de Not.) (anamorph Marssonina juglandis Lib.) Magn.). In the last years symptoms of the disease were observed with increasing frequency in Macedonia. The leaves, nuts, and occasionally shoots were affected. Leaf spots were dark brown, more or less circular and often coalesced forming larger dead areas. Black minute fruiting bodies called acervuli developed more abundantly on the under side than on the upper side of leaflets and produced a lot of conidia. Conidia were colorless, usually crescentshaped, rounded at one end and tapered at the other and divided by septa into two approximately equal cells. The severe attack caused defoliation in infected trees. The spots on the walnut husks were sunken and smaller than on the leaves. Early infection could lead to fruit deformation and they prematurely dropped. In the spring the perfect or sexual fungus G. leptostyla was found on fallen overwintered walnut leaves. Perithecia with long necks discharged numerous asci with ascospores serving as primary inoculum. Ascospores were hyaline, fusiform and bicelullar. Our results showed that both stages were involved in the disease under climatic condition of Macedonia. Collecting and burning or plowing the infected plant materials would aid in the control of this disease

Molecular identification and phylogenetic relationships of Colletotrichum isolates pathogenic on cultivated plants in Bulgaria

Fungi of the genus Colletotrichum are causal agents of plant diseases with constantly growing economic importance. Accurate pathogen identification is a significant prerequisite for effective disease control. The aim of the present investigation was to clarify the species affiliation of Colletotrichum isolates obtained from different hosts in Bulgaria and to determine the phylogenetic relationships between them by applying DNA barcoding. Thirty-five fungal isolates obtained from five botanical families (Solanaceae, Rosaceae, Musaceae, Cucurbitaceae and Caryophyllaceae) were morphologically characterized and subjected to molecular analysis based on four fungal barcode markers – the primary ITS barcode and the secondary marker regions ACT, EF-1a and TUB2 (Fig. 1). Three of the barcodes (ITS, ACT and TUB2) showed complete success rate of PCR amplification and sequencing and proved efficient for reliable identification at species level. BLAST analyses identified eleven Colletotrichum species assigned to five different complexes – C. coccodes, C. acutatum, C. gloeosporioides, C. dematium and C. spaethianum. The resolution power of ITS region was  not sufficient to discriminate interspecies variations within C. coccodes, C. dematium and C. spaethianum complexes confirming the requirement for secondary barcodes in order to resolve the genetic variability of the Colletotrichum isolates. DNA barcoding analyses revealed that the highest species variation was observed among the isolates from pepper (Capsicum annuum). Interestingly, an isolate from the same host identified as C. truncatum on the basis of morphological characters appeared to be C. circinans when applying DNA barcode markers. According to our knowledge, this species has not been reported as a causal agent of pepper anthracnose. Data obtained in this study improve our understanding of the genetic diversity within the Colletotrichum population pathogenic on cultivated plants in Bulgaria

Morphological, Pathological and Genetic Diversity of the <i>Colletotrichum</i> Species, Pathogenic on Solanaceous Vegetable Crops in Bulgaria

Colletotrichum species are among the most devastating plant pathogens in a wide range of hosts. Their accurate identification requires a polyphasic approach, including geographical, ecological, morphological, and genetic data. Solanaceous crops are of significant economic importance for Bulgarian agriculture. Colletotrichum-associated diseases pose a serious threat to the yield and quality of production but are still largely unexplored. The aim of this study was to identify and characterize 26 pathogenic Colletotrichum isolates that threaten solanaceous crops based on morphological, pathogenic, and molecular data. DNA barcodes enabled the discrimination of three main taxonomic groups: C. acutatum, C. gloeosporioides, and C. coccodes. Three different species of acutatum complex (C. nymphaeae, C. godetiae, and C. salicis) and C. cigarro of the gloeosporioides complex were associated with fruit anthracnose in peppers and tomatoes. The C. coccodes group was divided in two clades: C. nigrum, isolated predominantly from fruits, and C. coccodes, isolated mainly from roots. Only C. salicis and C. cigarro produced sexual morphs. The species C. godetiae, C. salicis, and C. cigarro have not previously been reported in Bulgaria. Our results enrich the knowledge of the biodiversity and specific features of Colletotrichum species, which are pathogenic to solanaceous hosts, and may serve as a scientific platform for efficient disease control and resistance breeding

Pepper as a target object of SEE-ERA.NET project

Pepper (Capsicum annuum var. annuum L.) is one of the most important and wide spread vegetables in the Balkan region. A great number of local populations with specific characteristics for shape, color, taste, biological value and type of use are grown in different Balkan countries together with the main commercial cultivars. Partially the old native forms are not within attention of the sort maintenance selection, but they are preserved in limited area and are valuable genetic resources. A SEE-ERA. NET project started in 2010 setting the task to investigate pepper as target species. The strategic objectives are: i) to collect, describe and explore the existing Capsicum biodiversity in the partner countries (Albania, Bulgaria, Greece, Macedonia and Serbia) related to valuable traits; ii) to create work and basic collections of local accessions and the respective database for more detailed and profound future collaborative investigations and breeding programs. Methods for description and maintenance of the collected material have been standardized in order to create a uniform description of existing local germplasm of pepper. First joint collecting expeditions have been carried out. Local expedition trips for expanding the national collections of old cultivars and domestic landraces have also been organized. Preparation of work and basic collections in the National Seed Genebank, Sadovo, Bulgaria, has started. The data will be publicly launched in the European Search Catalogue for Genetic Resources, EURISCO (www.eurisco.ecpgr.org). The data generated from this study, knowledge and collections will serve as a solid basis for effective preservation, management and exploitation of Balkan pepper germplasm biodiversity. The discovery of new sources of genetic variation and identification of accessions with valuable traits as pest resistance will be used in future pepper-breeding programs