Mapping of Avirulence Genes in the Rice Blast Fungus, Magnaporthe grisea, with RFLP and RAPD Markers

Abstract

Three genetically independent avirulence genes, AVR1-Irat7, AVRI-MedNoi; and AVR1-Ku86, were identified in a cross involving isolates Guy11 and 2/0/3 of the rice blast fungus, Magnaporthe grisea. Using 76 random progeny, we constructed a partial genetic map with restriction fragment length polymorphism (RFLP) markers revealed by probes such as the repeated sequences MGL/MGR583 and Pot3/MGR586, cosmids from the M. grisea genetic map, and a telomere sequence oligonucleotide. Avirulence genes AVR1-MedNoi and AVR1-Ku86 were closely linked to telomere RFLPs such as marker TelG (6 cM from AVR1-MedNoi) and TelF (4.5 cM from AVR1-Ku86). Avirulence gene AVR1-Irat7 was linked to a cosmid RFLP located on chromosome 1 and mapped at 20 cM from the avirulence gene AVR1-CO39. Using bulked segregant analysis, we identified 11 random amplified polymorphic DNA (RAPD) markers closely linked (0 to 10 cM) to the avirulence genes segregating in this cross. Most of these RAPD markers corresponded to junction fragments between known or new transposons and a single-copy sequence. Such junctions or the whole sequences of single-copy RAPD markers were frequently absent in one parental isolate. Single-copy sequences from RAPD markers tightly linked to avirulence genes will be used for positional cloning.

Diverse data supports the transition of filamentous fungal model organisms into the post-genomics era

“…Similarly, mating was studied in the saprophytic basidiomycete mushroom Coprinopsis cinerea and this system was ultimately exploited more for its synchronised meiosis than for its other features (Casselton & Kües 2007; Stajich et al 2010). The rice pathogen, Magnaporthe grisea , has been characterised extensively, from the production of a molecular genetic map (Dioh et al 2000), through comparative genome analysis (Donofrio et al 2014), and detailed analysis of the cell biology of infection (Giraldo et al 2013). While studied explicitly to understand its ability to cause disease in rice, M. grisea has emerged as a tractable model to understand the biology of the wheat-infecting variety of this fungus which has tremendous potential to impact wheat production in North America, Europe, and Asia (Pieck et al 2017).…”

Magnaporthe oryzae Genetic Diversity and Its Outcomes on the Search for Durable Resistance

“…Some of M. oryzae avirulence genes are located in telomeric and sub-telomeric regions, as is the case of Avr-Pita , AvrMedNoï-1; AvrKu86-1 (Dioh et al, 2000), Avr-Piz (Luo et al, 2002), Avr-Pii (Yasuda et al, 2006), Avr-Pi15 , and Avr-Pit and Avr-Pia . Deletions in these regions could result in Avr genes lost, resulting in virulence gain, as demonstrated by .…”

Marker-Based Cloning of the Region Containing the UhAvr1 Avirulence Gene From the Basidiomycete Barley Pathogen Ustilago hordei

“…In contrast, PWL2, AVR-Pita (forinfect members of the Gramineae, such as cereal crops and forage grasses. Infection occurs at the seedling stage merly called Avr2-YAMO), and avrCO39 of Magnaporthe grisea have been cloned by map-based approaches and the fungus grows within the meristematic tissue during development of the plant without showing symp- (Sweigard et al 1995;Farman and Leong 1998;Orbach et al 2000;Farman et al 2002). Several more toms.…”

“…Several more toms. At flowering, the fungus undergoes massive sporulation in the floral tissue and replaces the seeds with fungal Avr genes have been mapped on short genetic intervals in M. grisea (Dioh et al 2000), Leptosphaeria smut sori (Hu et al 2002). Teliospores from infected plants overwinter in the soil or on grain and reinitiate maculans (Attard et al 2002), and Blumeria graminis (Pedersen et al 2002).…”