ANALYSIS OF GENE EXPRESSIONS ASSOCIATED WITH INCREASED ALLELOPATHY IN RICE (Oryza sativa L.) UNDER LOW NITROGEN TREATMENT

Our previous studies showed that allelopathic activity and momilactone B concentration in rice seedlings were increased (6.9 times) in the presence of barnyardgrass seedlings. In this study we attempt to demonstrate the response of rice to the grass and Upregulation of the putative genes that encode phenyl-alanine ammonialyase (PAL), O-methyltransferase, triosephosphate-isomerase, and cytochrome P450, which are involved in phenolic allelochemicals synthesis. Suppression subtractive hybridization (SSH) technique was used in this study to investigate the up-regulate expression of genes in Rikuto Norin22 exposed to low N levels and cocultured with/without barnyardgrass in hydroponics. PAL is the first key enzyme in phenylpropanoid metabolism that can be regulated by various biotic and abiotic factors to different extents depending on different plant species and P450 is directly involved in the formation of pcoumaric acid. Rice genotypes, Giza182 like accession Rikuto Norin22 has strong allelopathic activity. In addition, our studies indicate that the accessions Giza182 is restorer line (data is not shown). So, we recommend using accession Giza182 as parental line in producing hybrid rice that has high yield and strong allelopathy like the hybrid (IR69625A x Giza182).