Metabolite profiles of rice cultivars containing bacterial blight-resistant genes are distinctive from susceptible rice

The metabolic changes of bacterial blight-resistant line C418/Xa23 generated by molecular marker-assisted selection （n = 12）, transgenic variety C418-Xa21 generated by using the Agrobacterium-mediated system （n = 12）, and progenitor cultivar C418 （n = 12） were monitored using gas chromatography/mass spectrometry. The validation, discrimination, and establishment of correlative relationships between metabolite signals were performed by cluster analysis, principal component analysis, and partial least squares-discriminant analysis. Significant and unintended changes were observed in 154 components in C418/Xa23 and 48 components in C418-Xa21 compared with C418 （P 〈 0.05, Fold change 〉 2.0）. The most signifi- cant decreases detected （P〈 0.001） in both C418/Xa23 and C418-Xa21 were in three amino acids： glycine, tyro- sine, and alanine, and four identified metabolites： malic acid, ferulic acid, succinic acid, and glycerol. Linoleic acid was increased specifically in C418/Xa23 which was derived from traditional breeding. This line, possessing a distinctive metabolite profile as a positive control, shows more differences vs. the parental than the transgenic line. Only succinic acid that falls outside the boundaries of natural variability between the two non-transgenic varieties C418 and C418/Xa23 should be further investigated with respect to safety or nutritional impact.