Development of scar marker linked with fungal virulence and study the expression patern of B-Glucosidase encoding genes in the rice blast fungus, magnaporthe oryzae

Abstract

Magnaporthe oryzae is a causal agent of blast disease, one of the most devastating disease in rice resulting significant crop losses worldwide. During the infection process, M.oryzae used both physical force and enzymatic activity for penetration of the defensive plant wall. Understanding of fungal virulence and its enzymatic expression have been known to play important role of the improvement of strategies in management of the rice blast disease. In previous study, pathogenicity test showed isolates collected in Binh Thuan province, Vietnam can break-down the blast resistance Jao Hom Nin (JHN) rice variety in Thailand. Genetic analysis of M.oryzae isolates was carried out by SRAP, there was approximately 400bp of specific band that was observed in at least four Binh Thuan blast isolates when using the pair of primers, me3 and em4. In addition, this blast linked to breaking-down blast resistance characteristic on rice. The sequencing of specific band indicated the presence of partial sequence of AVR-Pita2 gene and was used to design primers of SCAR markers. Re-amplification of SCAR primers was conducted to generate trait specific fingerprint linked to the blast resistance break-down of fungal isolates in rice resulting a potential application of SRAP-SCAR marker for screening of DNA fingerprinting and for controlling blast disease in the field. The target M.oryzae isolate identified from SCAR marker that was used to study on β-glucosidases expression as the key enzyme in last step of cellulose degradation. The result of qRT-PCR revealed the ideal time for β-glucosidases expression that is 72h after inoculation. Moreover, MGG_09738.6 gene that gave the highest expression in both used susceptible and non-susceptible rice variety as JHN and BC15 respectively.