Relationship between Disease Resistance and Rice Oxalate Oxidases in Transgenic Rice

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.

The oxalyl‐CoA synthetase‐regulated oxalate and its distinct effects on resistance to bacterial blight and aluminium toxicity in rice

“…In addition, oxalate can also be directly oxidised into CO 2 through the catalysis of oxalate oxidase, but this reaction seems less important for oxalate catabolism in plants, since the majority of plant species contain no such enzyme (Zhang et al . ; Li et al . ).…”

“…To the best of our knowledge, however, such a glyoxylate dehydrogenase that can reversibly catalyse the inter-conversion between oxalyl-CoA and glyoxylate has not been identified so far in plants. In addition, oxalate can also be directly oxidised into CO 2 through the catalysis of oxalate oxidase, but this reaction seems less important for oxalate catabolism in plants, since the majority of plant species contain no such enzyme (Zhang et al 2013;Li et al 2015). The location of OCS in the oxalate metabolism network is illustrated in Fig.…”

Reactive Oxygen Species Play a Role in the Infection of the Necrotrophic Fungi, Rhizoctonia solani in Wheat

“…Wheat and barley germins have been shown to be induced by abiotic stress and biotic stress, although the amount of induction does not necessary correlate with the level of biotic resistance observed [ 69 – 71 ]. In a number of instances, overexpression of germin in Arabidopsis, canola, soybean and tomato can lead to enhanced resistance to fungal pathogens [ 72 – 76 ], however reverse genetic studies of oxalate oxidase in transgenic wheats did not show a role of oxalate oxidase in response to bacterial blight [ 77 ].…”

Polyphenol oxidase as a biochemical seed defense mechanism

“…The class III peroxidases involved in host defense are wound- and pathogen-inducible, but in tobacco, peroxidase activity is not directly regulated by the defense phytohormones jasmonic acid and salicylic acid ( Hiraga et al, 2001 ). In contrast, host oxalate oxidases are induced during interactions with biotrophic pathogens but not by wounding ( Dumas et al, 1995 ; Zhang et al, 2013 ), suggesting different regulatory pathways among PPO, peroxidase, and oxalate oxidase, at least in leaves.…”