Investigation on Cultural Characterization and Parasexual Recombination in Pyricularia Grisea, Causal Agent of Blast of Rice

Abstract Blast of rice caused by Pyricularia grisea is one of the most devastating diseases of rice. Because of importance of the disease and the fact that pyricularia grisea is considered to be notorious and model species. The variability in cultural characteristics of fifty isolates of P. grisea were taken from different regions of Jharkhand state. Out of fifty isolates of P. grisea, colony color of six isolates were found to be as greyish white color, three isolates were blackish grey, six isolates as white color, three isolates as whitish grey color, five isolates were whitish black and twenty seven isolates were recorded as blackish white in color. The growth pattern of 47 isolates of P. grisea showed circular growth pattern and three isolates have irregular growth pattern but elevation of the mycelium differs from flat to raised. Out of fifty isolates of P. grisea, sector formation was observed in seventeen isolates and no sector formation was observed in rest isolates. The radial growth of fifty isolates of P. grisea were ranged from 76.0 mm to 90.0 mm. Out of fifty isolates, group I included six isolates, group II and III included eleven and thirty three isolates, respectively. Parasexual recombination rarely causes genetic and phenotypic variation through hyphal anastomosis in India. Parasexual recombination is the principle cause in rice blast fungus and cause infection of resistant rice variety (IR-64) in India .

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Effects of Rice Blast Fungus (Pyricularia grisea) on Phenolics, Flavonoids, Antioxidant Capacity in Rice (Oryza sativa L.)

International Letters of Natural Sciences ◽

10.18052/www.scipress.com/ilns.61.1 ◽

2017 ◽

Vol 61 ◽

pp. 1-7

Author(s):

Nguyen Phu Toan ◽

Pham Thi Thu Ha ◽

Tran Dang Xuan

Keyword(s):

Antioxidant Capacity ◽

Cinnamic Acid ◽

Rice Blast ◽

Rice Blast Fungus ◽

Blast Disease ◽

Pyricularia Grisea ◽

Rice Cultivars ◽

Blast Fungus ◽

Phenolic Components ◽

Dpph Scavenging

Rice blast fungus (Pyricularia grisea) is one of the most problematic pathogen to significantly reduce rice production worldwide. In this study, after being inoculated withP. grisea, changes in phenolic components and antioxidant capacity and correlation with the resistant level against rice blast fungus were investigated. Among screened rice cultivars, AV-3 was the strongest resistant, whereas BII-3 was the most susceptible. It was found that although total contents of phenolics and flavonoids, and antioxidant capacities varied among studied varieties, no significant coefficient with the resistance againstP. griseawas observed. After rice was affected by rice blast fungus, total phenolics and flavonoids were markedly reduced, but in contrast, the DPPH scavenging activities of only the susceptible rice cultivars was reduced. Among the 11 phenolic acids detected, catechol was found only in the tolerant cultivar AV-3, whereas the amount of cinnamic acid was increased after infection. Quantity of vanillin was also promoted, except in the susceptible cultivar BII-3 that was significantly reduced. Findings of this study showed that the resistant level againstP. griseawas proportionally correlated to the antioxidant capacity. Catechol, cinnamic acid, and vanillin may play a role but it needs further elaboration. Observations of this study suggested that the infection of blast disease by reducing amount of phenolics and flavonoids that may weaken the resistance of rice against this detrimental fungus.

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