Metabolic analysis of BPH-induced changes
To investigate the metabolite changes associated with the functions ofOsAP79 , rice lines OE, knockout, and NIP were treated with BPH,
and their metabolic compounds were identified using gas chromatography /
mass spectrometry (GC-MS). A total of 216 compounds were identified
(Table S5), and, according to principal component analysis (PCA), the
expression patterns were notably different among the three genotypic
lines (Figure S7 and S8). Of the 216 metabolites, 67 were mapped to the
KEGG pathway and are indicated in an integrated metabolic map (Table
S6). The mapped metabolites reflect the physiological state of BPH
infection and play crucial roles in BPH resistance. They mainly
participate in key metabolic pathways, such as the glycolysis,
biosynthesis of alkaloids derived from the shikimate pathway,
glucosinolate biosynthesis, and the citric acid cycle (Figure 6a and
6b).
Four key metabolic pathways were significantly enriched among the
different genotypic lines, indicating that they are involved in the
response to BPH feeding and may play a defensive role. Most of
significantly different metabolites associated with cell wall were
enriched in the shikimate pathway and citric acid cycle. Specifically,
compared with that in knockout lines, the synthesis of glucosinolates
such as valine, leucine, isoleucine, tyrosine, and phenylalanine,
significantly increased in resistant lines after BPH infection. However,
the content of D-glucose and fructose derived from glycolysis, citric
acid and 2-Oxoglutaric acid derived from citrate cycle and shikimic acid
decreased in OE and NIP lines when they were infected with BPH at 48 h
and 72 h; nevertheless, no significant change was detected in the
knockout lines (Figure 6a and 6b).