Flower color is one of the most important traits in ornamental plants. Poor coloration of pink flower chrysanthemum during the high temperature season is a serious problem. To determine the effect of high temperature on the pigmentation, inflorescence development was divided into five stages. Plants were exposed to both 20 and 30 during various developmental stages of inflorescence. HPLC analysis showed the main anthocyanins of pink flower chrysanthemum (cv. Pelican) were cyanidin 3-O-(6≤-O-monomalonyl-b -glucopyranoside) and cyanidin 3-O-(3≤,6≤-O-dimalonyl-bglucopyranoside). The content of the two anthocyanins at 20 was much higher than that at 30 . In the inflorescence exposed to 30 during bud break to vertical stage, pigmentation was not enhanced, even though the plants were subjected to 20 from the vertical stage to 1-week-old. On the other hand, when the plants were exposed to 30 during vertical stage to 1-week-old, pigment content decreased drastically, even though the inflorescence was kept at 20 from the bud break to vertical stage. The results indicate that the petal extension to vertical stage is the most temperature sensitive and important for pigmentation. Expression of the anthocyanin biosynthesis-related genes (CmplCHS1, CmplCHS2, CmplCHI, CmplF3H2, CmplC3'H, CmplDFR1, CmplDFR2, and CmplANS) was depressed at 30 compared with those at 20 .

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Bacterial wilt disease caused by the soil-borne bacterium, Ralstonia solanacearum species complex (formerly Pseudomonas solanacearum), causes great yield losses (Elphinstone, 2005). Because of the broad host range of and the limited control measures for R. solanacearum species complex, which attacks more 200 species representing 50 families of plants including the Solanaceae, Musaceae, Zingiberaceae and Cucurbitaceae (Hayward, 1994;She et al., 2017), the disease is difficult to manage. Bacterial wilt is a common disease in tropical, subtropical and warm temperate regions of the world. The disease is known to cause substantial damage to the economic plant production . The initial symptom is a drooping of leaves.Affected leaves later become permanently wilted, as the disease develops, a brown discoloration of xylem vessels in the stem is observed. A creamy or slimy mass of bacteria exudes from cut or broken vascular bundles. Eventually, plants fail to recover and become yellow and then necrotic (Charkowski et al., 2020;Dhital et al., 2000).In traditional classification schemes, R. solanacearum was currently classified into four biovars based on the oxidization of three

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