収穫後の高温処理によるカキ'富有'果肉中のカロテノイド含量の増強(収穫後の貯蔵・流通)  [in Japanese] Enhancement of Carotenoid Concentration in the Flesh of Japanese Persimmon 'Fuyu' by High Postharvest Temperature Treatments(Postharvest Physiology & Technology)  [in Japanese]

カキ果実の果肉中のカロテノイド含量を増強するため,収穫後の貯蔵温度(10〜25℃)がカロテノイド組成およびカロテノイド生合成関連酵素の遺伝子発現レベルに及ぼす影響について調査した.果肉に含まれる全てのカロテノイド類は,収穫後のどの貯蔵温度でも増加し,特にリコペンの増加は著しかった.25℃貯蔵では,カロテノイド生合成系の上流に位置するリコペン等のカロテン類だけでなく,下流に位置するβ-クリプトキサンチン等のキサントフィル類も増加した.また,生合成酵素のDK-LCYbやDK-HYbの遺伝子発現レベルも高く推移していた.このことから,貯蔵温度25℃はカロテノイド生合成が進みやすい条件であると考えられた.一方,10℃貯蔵では,カロテン類のみ増加し,DK-PSYやDK-ZDSの発現低下は少なく,DK-LcybやDK-Hybの発現が低下するため,リコペンの特異的な蓄積が起こったものと考えられた.また室温貯蔵では,両者の中間の傾向を示した.

To enhance carotenoid accumulation in the flesh of Japanese persimmons by postharvest treatment, the concentration of carotenoids and the expression of carotenoid biosynthetic genes were investigated at different storage temperatures, 25℃, 10℃ and room temperature (about 15.6℃). At 25℃, the concentrations increased not only in carotenes (lycopene, β-carotene and α-carotene), which were synthesized upstream to the carotenoid biosynthetic pathway, but also in xanthophylls (β-cryptoxanthin, zeaxanthin and lutein), which were synthesized downstream to the pathway, Especially in β-cryptoxanthin, the increase was remarkable. The gene expression of lycopene β-cyclase (DK-LCYb) and β-ring hydroxylase (DK-HYb), which are related to synthesis of β-cryptoxanthin and its precursor (β-carotene), was higher at 25℃ than at other temperatures. These results suggested that the storage temperature at 25℃ was good for carotenoid accumulation. However, at 10℃, the massive increase was observed only in the carotene concentration, especially in lycopene concentration. During 10℃ storage, the decrease in gene expression of phytoene synthase (DK-PSY) and ζ-carotene desaturase (DK-ZDS), which are related to synthesis of phytoene and lycopene, was small, although, the gene expression of DK-LCYb and DK-HYb decreased strikingly. At room temperature, carotenoid concentrations and gene expressions were between those at 25℃ and 10℃.