Fig 1.
Physical signs on different aroma types of melon at their commercial maturity period.
(A) Soluble solids content, (B) firmness, (C) per fruit weight, (D, E and F) pericarp color. The four types of melon included “Yu Meiren” (YMR), “Cui Bao” (CB); “Shao Gua” (SHAO) and “Cai Gua” (CAI). Duncan’s multiple range tests have been performed with different letters above the columns represent significant differences (P<0.05) between different types of melon.
Table 1.
Total and different classes of volatile compounds and their concentrations in different aromatic melon types.
Fig 2.
Principal component analysis (PCA) of the aroma volatiles identified in four types of melon at the commercial mature period.
The four types of melon included “Yu Meiren” (YMR), “Cui Bao” (CB), “Shao Gua” (SHAO) and “Cai Gua” (CAI). (A)Scores plots of the two main principal component analysis (PCA) of the aroma volatiles identified in four types of melon at the commercial mature period. (B) Loading plots of the two main principal component analysis (PCA) of the aroma volatiles identified in four types of melon at the commercial mature period. Each sample consisted of three replicates. Codes were corresponding to the volatile compounds number in S1 Table.
Fig 3.
LOX activities in different types of melon and oriental melon flesh tissue disks (A and B).
(A) LOX enzyme activity in flesh of different aroma types of melon. The four types of melon at the commercial mature period included “Yu Meiren” (YMR), “Cui Bao” (CB); “Shao Gua” (SHAO) and “Cai Gua” (CAI). (B) LOX enzyme activity in oriental melon flesh tissue disks. Disks were treated with 1.0 mM linoleic acid (LA), 0.5 mM linolenic acid (LeA), 0.1 mM n-propyl gallate (n-PG), or 0.1 mM nordihydroguariaretic acid (NDGA) in 0.4 M mannitol, for 12 h at 28°C, respectively. Disks treated with 0.4 M mannitol alone were used as a control. Duncan’s multiple range tests have been performed with different letters above the columns represent significant differences (P<0.05) between different types of melon.
Fig 4.
CmLOXs gene expression of different aroma types of melon at mature period.
All of the data for LOX gene expression are means ±SE of three replicates. Expression levels of each gene are expressed as a ratio relative to the LOX/18SrRNA ratios for CB, which was set to 1. Duncan’s multiple range tests have been performed with different letters above the columns represent significant differences (P<0.05) between different types of melon.
Fig 5.
Production of volatile compounds in in oriental melon flesh tissue disks.
Production of (A) hexanal, (B) (2E)-nonenal, (C) ethyl acetate, (D) propyl acetate, (E) butyl acetate, (F) amyl acetate, (G) hexyl acetate, (H) benzyl acetate and (I) phenethyl acetate in oriental melon flesh tissue disks. Disks were treated with 1.0 mM linoleic acid (LA), 0.5 mM linolenic acid (LeA), 0.1 mM n-propyl gallate (n-PG), or 0.1 mM nordihydroguariaretic acid (NDGA) in 0.4 M mannitol, for 12 h at 28°C, respectively. Disks treated with 0.4 M mannitol alone were used as a control. Duncan’s multiple range tests have been performed with different letters above the columns represent significant differences (P<0.05) between different treatments.
Fig 6.
Production of aldehydes, alcohols, straight-chain esters and other esters in oriental melon flesh tissue disks.
Disks were treated with 1.0 mM linoleic acid (LA), 0.5 mM linolenic acid (LeA), 0.1 mM n-propyl gallate (n-PG), or 0.1 mM nordihydroguariaretic acid (NDGA) in 0.4 M mannitol, for 12 h at 28°C, respectively. Disks treated with 0.4 M mannitol alone were used as a control. Duncan’s multiple range tests have been performed with different letters above the columns represent significant differences (P<0.05) between different treatments.
Fig 7.
CmLOXs gene expression in oriental melon flesh tissue disks.
Disks were treated with 1.0 mM linoleic acid (LA), 0.5 mM linolenic acid (LeA), 0.1 mM n-propyl gallate (n-PG), or 0.1 mM nordihydroguariaretic acid (NDGA) in 0.4 M mannitol, for 12 h at 28°C, respectively. Disks treated with 0.4 M mannitol alone were used as a control. All of the data for LOX gene expressions are means ±SE of three replicates. Expression levels of each gene are expressed as a ratio relative to a control, which was set at 1. Duncan’s multiple range tests have been performed with different letters above the columns represent significant differences (P<0.05) between different treatments.