Cloning and sequence analaysis of AvrPiz-t gene from Magnaporthe oryzae isolates from Sarawak

Jee, Mui Sie (2016) Cloning and sequence analaysis of AvrPiz-t gene from Magnaporthe oryzae isolates from Sarawak. [Final Year Project Report] (Unpublished)

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Abstract

Magnaporl!7e OIyzae is a fungal pathogen responsible for rice blast disease all over the globe. Resistance or susceptibility of a rice cultivar results from the interaction between R (resistance) gene of the plant and Avr (avirulence) gene of the pathogen. While more research focus on the functions ofR gene, it should be aware that Avr gene also plays an important role in plant disease control. In this study, full-length cod ing sequence of AvrPizI gene was studied by initial fungal species verification using uni versa l primer pair ITS 1IITS4 followed by AvrPiz-1 gene isolation by direct peR using specific primer pair. Then, the amp lified gene was subjected to cloning prior to subsequent sequencing. The presence of AvrPiz-1 gene with an open reading frame of 326 bp encoding for 108 amino acid residues was detected and confirmed in M. oryzae 7', a Sarawak isolate . From the sequencing output, three uncharacterized nucleotide mutations were found across pairwise sequence alignment with an avirulent strain. Thus, the functional sign ificance of these sequence variations on the avirulent phenotype of AvrPi::-1 gene found ha s yet to be investigated. Not forgotten, several high occurrence motifs usually involved in signal transduction pathways were detected across the nucleotide translated protein sequence. This suggests the possible role of the avirulence protein in host-pathogen interaction. Most importantly, a novel motif was predicted across the protein sequence of five avirulence proteins (AvrPiz-l, AvrPi9, A VR -Pia, AVR-Pii, and AvrPib) invo lving in the triggering of plant defe nse system. This imply that the proteins might share some degree of unknown similarity which might un veil the mechanism of funga l pathogenesis and therefore useful for the study in rice blast control.

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