Molecular, physiological and pathogenic variability of Pyrenochaeta lycopersici associated with corky rot disease of tomato plants in Turkey

Abstract

Isolates of Pyrenochaeta lycopersici, the causal agent of corky root rot on tomato plants, were assessed for physiological and genetic characteristics using conventional and molecular techniques. All isolates were able to produce necrosis on tomato roots and classified into temperature group according to the optimal growth temperatures. Specific-PCR assays and DNA sequence analysis of the ribosomal DNA (rDNA) internal transcribed spacer region confirmed the existence of both types (Type 1 and Type 2) of the pathogen among the isolates tested. All isolates were identified as Type 2 except for isolate Pl-4, which was classified as Type 1. Restriction fragment length polymorphism (RFLP) analysis with six enzymes resulted in three distinct banding patterns among the isolates depending on the length and restriction profiles of the rDNA intergenic spacer region. Inter-simple sequence-repeat analysis revealed a high level of genetic diversity among the isolates in agreement with the data of RFLP analysis. These results indicated that there were three different intraspecific groups among Turkish isolates of P. lycopersici. The presented study is the first attempting to characterize Turkish isolates of P. lycopersici. The results obtained will be useful in screening of tomato seedlings for resistance to P. lycopersici.

Genetic structure of Italian populations of Pyrenochaeta lycopersici, the causal agent of corky root rot of tomato

“…Interestingly, this was also suggested by another study using PCR-RFLP and ISSR markers on a small set of 25 T2 isolates from Turkey (Bayraktar & Oksal, 2011). However, it should be noted that only one T1 isolate was included in this study, i.e.…”

“…The T2 isolates appear to be more prevalent in Italy, Turkey and Japan (Infantino & Pucci, 2005;Bayraktar & Oksal, 2011;M. Hyakumachi, Gifu University, Japan, personal communication).…”

“…This has probably been because of the difficulties in recognizing this disease in the field, due to the absence of specific symptoms on the above-ground parts of the plants, the need for the destruction of the plant to recover the fungus from the roots, and the overgrowth of other faster-growing fungi during the reisolation procedure. Molecular characterization of P. lycopersici populations using random amplified polymorphic DNA, PCR-restriction fragment length polymorphism (RFLP) of intergenic spacers, and internal transcribed spacer (ITS) regions and inter-simple sequence repeats (ISSRs), have reported low levels of genetic and genotypic diversity (Infantino et al, 2003;Bayraktar & Oksal, 2011). The existence of two types of P. lycopersici (type 1, type 2; hereafter T1, T2) was proposed by Sugiura et al (2003).…”

De novo genome assembly of the soil-borne fungus and tomato pathogen Pyrenochaeta lycopersici

“…The sequencing of 18S nrDNA (SSU) and 28S nrDNA (LSU) indicate that P. lycopersici is an ascomycete in the order Pleosporales, along with other necrotrophic and hemibiotrophic plant pathogens representing genera such as Cochliobolus, Pyrenophora, Phaeosphaeria, Leptosphaeria, Pleospora, Phoma and Didymella [ 9 ] . A low grade of genetic variability was shown within P. lycopersici isolates, when investigated by RAPD and RFLP analysis [ 10 ], and the use of ISSR and AFLP markers [ 11 , 12 ].Little is known about the biology, life cycle and infection structures of this species. A telomorph has not been described and even the anamorph is rare in nature.…”