Institute for Horticultural Plants, China Agricultural University, Beijing, China.
J Pineal Res. 2013 Aug;55(1):79-88. doi: 10.1111/jpi.12044. Epub 2013 Mar 11.
Melatonin is a well-known molecule which possesses many beneficial effects on human health. Many agriculture products provide natural melatonin in the diet. Cherry is one such fruit as they are rich in melatonin. In order to understand the biological roles of melatonin in cherry fruit, melatonin synthesis and its changes over 24 hr period were systematically monitored both during their development and in the ripe cherries in two cultivars, 'Hongdeng' (Prunus avium L. cv. Hongdeng) and 'Rainier' (Prunus avium L. cv. Rainier). It was found that both darkness and oxidative stress induced melatonin synthesis, which led to dual melatonin synthetic peaks during a 24 hr period. The high levels of malondialdehyde induced by high temperature and high intensity light exposure were directly related to up-regulated melatonin production. A primary function of melatonin in cherry fruits is speculated to be as an antioxidant to protect the cherry from the oxidative stress. Importantly, plant tryptophan decaboxylase gene (PaTDC) was identified in cherry fruits. Our data shows that PaTDC expression is positively related to the melatonin production in the cherry. This provides additional information to suggest that tryptophan decaboxylase is a rate-limiting enzyme of melatonin synthesis in plants.
褪黑素是一种众所周知的分子，对人类健康具有许多有益的影响。许多农产品在饮食中提供天然褪黑素。樱桃就是这样一种水果，因为它们富含褪黑素。为了了解褪黑素在樱桃果实中的生物学作用，我们系统地监测了两个品种（‘Hongdeng’（Prunus avium L. cv. Hongdeng）和‘Rainier’（Prunus avium L. cv. Rainier））在发育过程中和成熟樱桃中 24 小时周期内褪黑素的合成及其变化。结果发现，黑暗和氧化应激均可诱导褪黑素合成，导致 24 小时周期内出现双重褪黑素合成峰。高温和高强度光照引起的高水平丙二醛与上调的褪黑素产生直接相关。推测褪黑素在樱桃果实中的主要功能之一是作为抗氧化剂来保护樱桃免受氧化应激。重要的是，在樱桃果实中鉴定出植物色氨酸脱羧酶基因（PaTDC）。我们的数据表明，PaTDC 的表达与樱桃中褪黑素的产生呈正相关。这提供了额外的信息，表明色氨酸脱羧酶是植物褪黑素合成的限速酶。
