Integrated Transcriptome and Metabolome Analysis Revealed That Flavonoid Biosynthesis May Dominate the Resistance of Zanthoxylum bungeanum against Stem Canker

Stem canker of Zanthoxylum
bungeanum is a devastating disease that seriously
affects the plantation and
industrial development of Z. bungeanum due to a lack of effective control measures. The objective of this
study was to screen out resistant Z. bungeanum varieties and further explore their resistance mechanisms against
stem canker. Results showed that the most resistant and susceptible
varieties were, respectively, Doujiao (DJ) and Fengxian Dahongpao
(FD). Combining transcriptomic and metabolomic analyses, we found
that the genes and metabolites associated with the phenylpropanoid
metabolism, especially flavonoid biosynthesis, were highly significantly
enriched in DJ following pathogen infection compared with that in
FD, which indicated that the flavonoid metabolism may positively dominate
the resistance of Z. bungeanum. This
finding was further confirmed by quantitative real-time polymerase
chain reaction analysis, through which higher expression levels of
core genes involved in flavonoid metabolism in resistant variety were
observed. Moreover, by analyzing the differences in the flavonoid
content in the stems of resistant and susceptible varieties and the
antifungal activities of flavonoids extracted from Z. bungeanum stems, the conclusion that flavonoid
metabolism positively regulates the resistance of Z.
bungeanum was further supported. Our results not only
aid in better understanding the resistance mechanisms of Z. bungeanum against stem canker but also promote
the breeding and utilization of resistant varieties.