Abstract
Differential expression of rice oxalate oxidase genes (OsOxO1-4) in rice leaves (Oryza sativa L.) in response to biotic stress was assayed using RT-PCR. OsOxO4 was induced transiently at 12 h in plants inoculated with the pathogens of bacterial blight and that of the wounding control. Inoculation with the rice blast pathogen induced OsOxO2 expression compared to the mock spray control. Overexpressing OsOxO1 or OsOxO4 in rice resulted in elevated transcript levels of the respective transgene as well as OsOxO3 in leaves compared to that in untransformed wild type (WT). In a line of RNA-i transgenic rice plants (i-12), expression of all four OsOxO genes except that of OsOxO2 was severely inhibited. Oxalate oxidase (OxO, EC 1.2.3.4) activity in plants overexpressing OsOxO1 or OsOxO4 was substantially higher than that in WT and the RNA-i lines. It was found that transgenic rice plants with substantially higher OxO activity were not more resistant to rice blast and bacterial blight than WT. In contrast, some RNA-i lines with less OxO activity seemed to be more resistant to rice blast while some overexpressing lines were more susceptible to rice blast than WT. Therefore, OxO might not be a disease resistance factor in rice.
Highlights
The first germin was found during a search for germinationspecific proteins in wheat [1,2]
OsOxO4 was induced after inoculation with Magnaporthe oryzae (M. oryzae) and Xanthomonas oryzae pv. oryzae (Xoo) [8], and some OsGLPs could be induced by M. oryzae infection [9]
Effects of bacterial blight and rice blast on expression of OsOxO genes in rice leaves Only OsOxO4 transcript was detected in leaves at time 0
Summary
The first germin was found during a search for germinationspecific proteins in wheat [1,2]. The transcription of germin-like oxalate oxidase gene in wheat and barley leaves increased following pathogen attack [6,7], and OxO activity induced by powdery mildew fungus was found exclusively in the cell wall of barley leaf mesophyll cells. This has led to the hypothesis that OxO might be responsible for production of H2O2 which is involved in the regulation of the hypersensitive response during plant-pathogen interactions [6]. The precise mechanism whereby OxO could contribute to plant disease resistance remains unclear
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have