Caracterização, compatibilidade e ocorrência de reprodução sexual entre isolados de Pyricularia grisea de diferentes hospedeiros

Abstract

A brusone, causada por Pyricularia grisea (teleomorfa Magnaphorthe grisea), possui uma ampla gama de hospedeiros. No Brasil, arroz, trigo, triticale e cevada são as culturas que sofrem quedas significativas de produtividade devido ao ataque desse patógeno. Além desses cereais, outras gramíneas também têm apresentado sintomas dessa doença. Os objetivos dessa pesquisa foram: a) caracterizar sexualmente isolados de P. grisea desses hospedeiros baseado na determinação do "mating type", fertilidade, sexualidade, compatibilidade sexual, b) analisar o grau de compatibilidade sexual entre isolados de brusone de trigo e de outras gramíneas, c) estudar a ocorrência da reprodução sexual em isolados de trigo. Os resultados obtidos através de ensaios "in vitro" constataram: 1) compatibilidade sexual de P. grisea do trigo com Bromus catharticus, Phalaris canariensis e X. triticosecal; 2) desbalanço entre porcentagem de MAT1-1 e MAT1-2, com predominância de MAT1-1 na população de P. grisea do trigo; 3) existência de um campo de isolados de trigo com baixa habilidade de cruzamento; 4) baixa possibilidade de ocorrência de reprodução sexual de P. grisea em campos de trigo, mesmo com existência de ambos "mating type" num mesmo campo.

Host range, mating type and population structure of Magnaporthe sp. of a single barley field in São Paulo state, Brazil

“…The predominance of a single mating type is one indication of the absence of sexual reproduction in a population (Milgroom, ). Our result is in agreement with a previous finding showing that barley isolates were unable to cross, despite high mating ability of parental isolates and preferable mating conditions (Galbieri & Urashima, ). Mechanism that may be involved in the genotypic diversity of barley blast such as mutation, heterokaryosis and parasexual recombination (Crawford, Chumley, Weaver, & Valent, ; Noguchi, Yasuda, & Fujita, ) were not investigated in the present work.…”

“…from barley showed similar Pot2 DNA fingerprinting to three isolates of wheat blast (Urashima, Dias Martins et al, 2004). The identification of two additional genotypically distinct barley blast lineages (CVPN02-18a and CVPN02-08a, CVPN02-17c, CVPN02-27d) with ≥50% divergence to wheat isolates was surprising (Figure 1 wheat blast population at both phenotypic (mating ability and sex organ production) and genotypic traits (fingerprinting by MGR583) (Galbieri & Urashima, 2008;Urashima, Galbieri, & Stabili, 2005).…”

“…The identification of two additional genotypically distinct barley blast lineages (CVPN02‐18a and CVPN02‐08a, CVPN02‐17c, CVPN02‐27d) with ≥50% divergence to wheat isolates was surprising (Figure ). Wheat isolates employed in the present work were representative of the diversity shown by the wheat blast population at both phenotypic (mating ability and sex organ production) and genotypic traits (fingerprinting by MGR583) (Galbieri & Urashima, ; Urashima, Galbieri, & Stabili, ). Therefore, the possibility of the involvement of an undetected subpopulation of wheat blast in these two lineages of Magnaporthe sp.…”

Sanitary quality of Brachiaria brizantha cv. Marandu and Xaraés seeds harvested in different states in Brazil

“…In Brazil, rice, wheat, triticale, and rye are the crops which undergo expressive reductions of productivity due to attacks by that pathogen -this pathogen interferes directly in the photosynthetic process (GALBIERI; URASHIMA, 2008). Beyond those crops, this pathogen is also capable of infecting several forage grasses and weeds, such as Brachiaria decumbens, B. plantaginea, Lollium multiflorum, Avena strigosa, Echinochloa cruz-galli, among others (GALBIERI; URASHIMA, 2008;MARCHI et al, 2005).…”

Reprodução Sexuada em Pyricularia oryzae

“…(Bromus catharticus Vahl), alpiste (Phalaris canariensis L.) e triticale (X. triticosecal Wittmack) (18). O idiomorfo Mat1-1 predominou nas populações amostradas nos Estados do Mato Grosso do Sul, Paraná e São Paulo.…”