Citrus family is one of the most commercially important fruit crops and well known as an important source of nutrient and bioactive compounds. However, the physiology especially on the stress condition of this plant family has not been fully understood yet. Our previous studies demonstrated that metabolic profiles of primary and volatile compounds in several Citrus species were changed after stress treatments, and the manner of response against stresses were demonstrated to be different among Citrus species. However, changes in non-volatile secondary metabolites such as flavonoids and phenolics, well known as defense compounds, during defense responses are still unknown. In the present study, we performed comprehensive analysis of non-volatile secondary metabolites in leaves of four Japanese Citrus plants (C. unshiu, C. kinokuni, C. grandis, and C. hassaku) using LC-QTOF system. As stress treatments, we performed wounding as well as plant hormone treatments with jasmonic acid and salicylic acid which are well-known as an environmental stress response signal. The leaf metabolites were extracted with MeOH after stress treatments, and the extracts were applied to TripleTOF 5600+ (AB SCIEX) combined with Shimadzu LC-20A system. The resulting peak data was applied to orthogonal partial least squares-discriminant analysis using SIMCA ver. 13.0.3 (Umetrics, Sweden). As a result, the responses against wounding, total fifty-one stress-responsive peaks were detected, and among them, three peaks were commonly detected in all of the species tested. These results suggest that these three compounds are common biomarkers candidates in Citrus plants for stress responses. In the presentation, we will show details of changes in metabolite profiles and discuss the similarities and differences in four species.

Metabolic profiling of leaf secondary metabolites in Japanese citrus cultivars under stress conditions

2019 Fall National Meeting

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