Pathogenic variation among isolates of<i>Pyricularia oryzae</i>affecting rice, wheat, and grasses in Brazil

Prabhu, A. S.; Filippi, Marta Cristina Corsi de; Castro, Nélio Ricardo Amaral

doi:10.1080/09670879209371729

Cited by 80 publications

(61 citation statements)

References 7 publications

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“…The Brazilian pathotypes were differentiated on the basis of reaction on eight local commercial upland rice cultivars (Prabhu et al, 2002). The international and Brazilian pathotypes were prefixed by the letter "I" and "B", respectively.…”

Section: Methodsmentioning

confidence: 99%

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Resistance spectra of six elite breeding lines of upland rice to Pyricularia grisea

Prabhu

Castro

Araújo

et al. 2003

Pesq. agropec. bras.

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-The objective of this work was to evaluate the resistance spectra of six elite breeding lines of rice, developed for improved yield and grain quality, in inoculation tests in the greenhouse and in the field. Forty-six isolates of Pyricularia grisea collected from the cultivar Primavera, 31 from the cultivar Maravilha and 19 from six elite breeding lines, totaling 96 were utilized for inoculations. Out of 11 international and 15 Brazilian pathotypes, IC-1, IB-9, and BD-16, respectively, were identified as most frequent isolates collected from the cultivar Primavera. The isolates retrieved from Maravilha belong to four international and 11 Brazilian pathotypes, the predominant ones being IB-9 and IB-49 and BB-1 and BB-21, respectively. Lines CNA s 8711 and CNA s 8983 showed resistant reaction to all test isolates from Maravilha, while CNA s 8983 was susceptible to three isolates of Primavera pertaining to the pathotype IC-1. A majority of isolates exhibiting compatible reaction to Primavera were incompatible to Maravilha and vice-versa. Field assessment of rice blast utilizing the area under disease progress curve as a criterion for measuring disease severity showed significant differences among the six breeding lines. The isolates of P. grisea exhibiting differential reaction on breeding lines can be utilized in pyramiding resistance genes in new upland rice cultivars.Index terms: Oryza sativa, pathotypes, physiologic races, rice blast, inoculation methods. Espectro de resistência de seis linhagens elites de arroz de terras altas a Pyricularia griseaResumo -O objetivo deste trabalho foi avaliar o espectro de resistência de seis linhagens elites de arroz de terras altas, desenvolvidas para maior produtividade e qualidade superior de grãos, através de testes de inoculação em casa de vegetação e no campo. Nos testes de inoculação, foram utilizados 96 isolados de Pyricularia grisea, sendo 46 provenientes da cultivar Primavera, 31 da cultivar Maravilha e 19 de seis linhagens elites. Os patótipos internacionais IC-1 e IB-9, e os patótipos brasileiros BD-16 foram identificados como mais freqüentes entre os isolados coletados da cultivar Primavera. Os isolados da cultivar Maravilha pertenceram a quatro patótipos internacionais e a 11 patótipos brasileiros com predominância de IB-9, IB-49, BB-1 e BB-21, respectivamente. Enquanto as linhagens CNA s 8711 e CNA s 8983 apresentaram reações de resistência para todos os isolados oriundos da cultivar Maravilha, CNA s 8983 mostrou reação suscetível para três isolados de Primavera, pertencentes ao patótipo IC-1. A maioria dos isolados que apresentaram reações compatíveis com a cultivar Primavera foram incompatíveis com a cultivar Maravilha e vice-versa. As avaliações no campo mostraram diferenças significativas entre as linhagens com relação à área sob curva de progresso da brusone nas folhas. Os isolados de P. grisea que apresentaram reações diferenciais nas linhagens podem ser utilizados para a piramidação de genes em novas cultivares de arroz de terras altas.Termos pa...

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Section: Methodsmentioning

confidence: 99%

“…Mycelial growth, sporulation on culture medium and inoculation procedure were carried out as described in earlier investigations (Prabhu et al, 1992;. Leaf blast reaction was assessed seven to nine days after inoculation taking into consideration only two types of reaction of the host, compatible (susceptible) and incompatible (resistant).…”

Section: Methodsmentioning

confidence: 99%

Resistance spectra of six elite breeding lines of upland rice to Pyricularia grisea

Prabhu

Castro

Araújo

et al. 2003

Pesq. agropec. bras.

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“…Prabhu et al (1992) reported that all of the P. grisea isolates from rice, wheat and grass weeds were pathogenic on the wheat cultivars and barley, but none of the 10 wheat and seven grass isolates infected any of the 30 rice cultivars. Similarly Mehta and Baier (1998) reported variation for virulence and host specificity among P. grisea isolates from triticale.…”

Section: Seed and Secondary Hosts As Source Of Primary Inoculummentioning

confidence: 99%

“…However, seed infection seems to play only a minor role in the epidemiology of the disease because spike infection comes from the air-borne conidia mainly from several secondary hosts (Prabhu et al 1992;Urashima et al 1993). Several grass weeds (Cenchrus echinatus, Eleusine indica, Digitaria sanguinalis, Brachiaria plantaginea, Echinocloa crusgalli, Pennisetum setosum, Hyparrhenia rufa and Rhynchelytrum roseum) occur commonly in wheat and rice fields of Brazil and are secondary hosts of Pyricularia, but their role in the epidemiology of wheat blast is not well understood (Prabhu et al 1992). In Bolivia, Eleusine indica, Digitaria sanguinalis and Rottboelia exaltata have been identified with blast symptoms (Hurtado & Toledo 2005).…”

Section: Seed and Secondary Hosts As Source Of Primary Inoculummentioning

confidence: 99%

Pyricularia blast - a threat to wheat cultivation

Kohli¹,

Mehta²,

Rodríguez-Guzmán³

et al. 2011

Czech J. Genet. Plant Breed.

178

181

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Wheat blast disease caused by Pyricularia grisea (telemorph Magnaporthe grisea) has become a serious restriction on increasing the area and production of the crop, especially in the tropical parts of the Southern Cone Region of South America. First identified in 1985 in the State of Paraná in Brazil, it has become an endemic disease in the low lying Santa Cruz region of Bolivia, south and south-eastern Paraguay, and central and southern Brazil in recent years. Severe infections have also been observed in the summer planted wheat crop in north-eastern Argentina. So far, only sporadic infections have been seen in Uruguay, especially during the wet and warm years. Spike infection (often confused with Fusarium head blight infection) is the most notable symptom of the disease and capable of causing over 40% production losses. However, under severe infection, the loss of production can be almost complete in susceptible varieties. Wheat blast is mainly a spike disease but can also produce lesions on all the above ground parts of the plant under certain conditions. Depending upon the point of the infection on the rachis, the disease can kill the spike partially or fully. The infected portion of the spike dries out without producing any grain which can be visibly distinguished from the healthy portion. While virulence diversity in the fungus has been reported in the literature and is under further exploration, genetic resistance in the host species has been more difficult to identify. Earlier, Brazilian cultivars such as BH 1146, CNT 8, several IAC and OCEPAR selections were credited as demonstrating different levels of field resistance, but this was not confirmed under artificial inoculation studies. However, other cultivars such as BR18, IPR 85, CD 113, have shown moderate levels of resistance over the years in many locations. Recently, several cultivars and advanced lines derived from the CIMMYT line, Milan, have been observed to carry a high level of resistance to blast disease throughout the endemic region. However, to date, the genetic basis of this resistance is not very clear due to extreme variation in the pathogen. Cultivars showing complete resistance against a few isolates under controlled conditions in the glasshouse, may or may not show field resistance in commercial cultivation. Due to an increase of the area under Milan based resistant wheat cultivars in Bolivia, Brazil and Paraguay, it needs to be combined with other sources of resistance urgently to prevent the selection of a virulent pathotype in the fungus. Besides genetic resistance, avoidance of early dates of seeding and chemical control can reduce the disease severity. Fungicides combining triazols with strobilurins can, under some situations, be effective in disease control at the heading stage. Even when all components of integrated disease management of wheat blast are not in place yet, it is seen as an essential strategy to reduce production losses in this region. Given the threat that the blast disease may pose to world wheat growin...

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“…O patógeno que inicialmente foi identificado em alguns municípios do norte do Paraná, rapidamente se disseminou para outras regiões tritícolas do país: São Paulo (Igarashi, 1990), Rio Grande do Sul (Picinini & Fernandez, 1990), Mato Grosso do Sul (Goulart et al, 1990), Goiás (Prabhu et al, 1992), cerrado do Brasil Central (Anjos et al, 1996). Goulart & Paiva (2000) observaram redução de 51% do rendimento de grãos e incidência de 86% em campos de trigo no estado de Mato Grosso do Sul na safra 1991 e 1992 e mais recentemente Urashima et al (2009) (Greer & Webster, 2001) e pela disseminação do fungo em trigo do Paraná para o Mato Grosso do Sul (Urashima et al, 1999).…”

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Eficiência de tratamentos alternativos no controle de Pyricularia grisea em sementes de trigo

Silva¹,

Nomura²,

Freitas³

et al. 2009

Trop. plant pathol.

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RESUMOO presente trabalho objetivou estudar métodos alternativos de controle de Pyricularia grisea, em sementes de trigo, uma das principais fontes de inóculo da brusone. Após ensaios preliminares para avaliação do efeito dos produtos, em diferentes concentrações, tempos e temperaturas de imersão sobre a germinação das sementes, os tratamentos hipoclorito de sódio (2%; pH 11,5; 50°C; 10 min) e (2%; pH 11,5; 50°C; 10 min) e água quente (55°C/5min) foram selecionados para estudar sua eficiência no controle de P. grisea e transmissão do patógeno para plântula. O delineamento estatístico constou de 400 sementes em 4 repetições em blocos ao acaso. A incidência do fungo foi examinada do 2º. ao 4º. dia através do "blotter test" a 22ºC com fotoperíodo de 12h, a germinação das sementes foi avaliada aos 7 dias através da observação visual da emissão do tubo germinativo e a transmissão aos 7 e 14 dias pela identificação de conídios de P. grisea das lesões necróticas que surgiram em qualquer tecido da parte aérea. Dados do presente estudo revelaram que o tratamento hipoclorito de sódio (pH 11,5/50ºC/ 10min) foi eficiente no controle de P. grisea em sementes de trigo pois reduziu a incidência inicial de 57,7% para 2,25%, mas reduzindo significativamente a germinação para 46%. O tratamento hipoclorito de sódio reduziu a transmissão do patógeno para plântulas de 39,7 para 0,5%. Palavras-chave: Magnaporthe grisea, Triticum aestivum, brusone, controle alternativo, sementes ABSTRACT Efficiency of alternative treatments in the control of Pyricularia grisea in wheat seedsThe present study aimed to examine alternative methods of control of Pyricularia grisea in wheat seeds, one primary source of blast disease. The treatments sodium hypochlorite (2%; pH11,5; 50C; 10min) and hot water (55°C/5min) were selected after preliminary trials that examined the effect on germination of several reagents, at different concentrations, temperatures and period of submersion. Their efficiency in controlling P. grisea in wheat seeds and its transmission to seedlings was studied in seed lots of 400 in four replications in a randomized block design. The fungal incidence was analyzed through blotter test employing 22ºC and photoperiod of 12 h from the second to fourth day, seed germination at the seventh day through visual emergence of germ tube and transmission to seedlings at the seventh and 14 th days through identification of P. grisea conidia from necrotic lesions of any aerial tissues. The present data revealed that sodium hypochlorite (pH 11.5/50ºC/10min) was effective in controlling P. grisea in wheat seeds because it decreased the initial incidence from 57.7% to 2.25% but with deleterious effect on germination. This treatment reduced the fungal transmission to seedlings from 39.7 to 0.5%.

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Pathogenic variation among isolates ofPyricularia oryzaeaffecting rice, wheat, and grasses in Brazil

Cited by 80 publications

References 7 publications

Resistance spectra of six elite breeding lines of upland rice to Pyricularia grisea

Resistance spectra of six elite breeding lines of upland rice to Pyricularia grisea

Pyricularia blast - a threat to wheat cultivation

Eficiência de tratamentos alternativos no controle de Pyricularia grisea em sementes de trigo

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