硒诱导甜樱桃褪黑素合成机制研究

Both melatonin and selenium (Se) play important roles in improving human immunity and anti-cancer. Currently, Se-enrich and high-melatonin fruit production is an important industry goal for horticultural crops. Sweet cherry is one of the fruits with high melatonin, and our previous experiments showed that the melatonin contents was closely related to Se. However, the mechanism of the biosynthesis of melatonin enhanced by Se was largely unknown. In this study, ‘Brooks’ and ‘Russia No. 8’, different melatonin content cultivars, were selected as materials. Homogeneous three-scion-two rootstock system and heterogeneous double-scion-one-rootstock system were used as special experimental methods. Moreover, filed and greenhouse tests were combined. Metabolites and gene expression of melatonin biosynthesis pathway, affected by Se, were compared in leaves and fruits under the gradient of low Se concentration (0-0.4 mg·kg-1). The mathematical model was established between Se and melatonin content. Meanwhile, the differences of physiological parameters, such as photosynthetic capacity and antioxidant capacity of sweet cherry, were also evaluated. Then, the key limiting factors of melatonin biosynthesis will be elucidated in sweet cherry, the molecular mechanism of the biosynthesis of melatonin enhanced by Se will be revealed. The technology, Se-rich sweet cherry produced by secondary transformation of Se from natural grass in orchard, will be obtained, providing an important basis for the production of Se-rich and high-melatonin healthy sweet cherry.

褪黑素和硒均在提高人体免疫力、抗癌等方面有着重要作用。富硒高褪黑素水果是目前保健性果树重要栽培目标之一。甜樱桃含有较高的褪黑素，项目组前期研究发现硒与褪黑素含量有密切关系，但目前硒诱导褪黑素生物合成机制尚不明确。本项目拟以褪黑素含量差异较大的‘布鲁克斯’和‘俄罗斯8’品种为试材，利用同质三接穗双砧木、异质双接穗单砧木等方法以及避雨和露天试验相结合。在低硒浓度梯度下，比较硒酸盐、硒代蛋氨酸和果园自然生草二次转化硒三种形态硒对褪黑素生物合成途径关键酶基因转录表达和合成前体物质在叶片和果实上的影响，并建立硒与褪黑素关系模型。于此同时，评价分析不同形态硒对甜樱桃生理参数如光合能力、抗氧化水平、果实品质的影响。从而阐明甜樱桃褪黑素生物合成的关键限制因子，揭示硒促进褪黑素合成的分子机制，并获得利用果园自然生草二次转化硒生产富硒甜樱桃技术，为生产富硒高褪黑素保健型甜樱桃提供重要依据。

褪黑素和硒在提高人体免疫力、抗癌等方面起着重要作用。富硒高褪黑素水果是目前保健性果树重要栽培目标之一。本项目以褪黑素含量相对较高的‘俄罗斯8号’甜樱桃为试材，利用设施盆栽和地栽甜樱桃苗分析在不同形态硒、不同浓度硒处理下甜樱桃生长、生理参数以及褪黑素合成代谢途径和果实品质的影响，从而揭示了甜樱桃褪黑素合成受硒剂量的影响，探索了5-甲氧基色氨酸参与褪黑素的合成，明确了硒在甜樱桃体内有一定的移动性并影响碳氮营养元素。低剂量硒短期处理对甜樱桃生长呈现出明显的促进作用，而长期处理下甜樱桃的生长受到抑制并且存在明显的排硒现象，可溶性糖和叶片氮素变化可作为甜樱桃硒胁迫的主要依据。高剂量硒处理明显抑制地上部生长，促进地下部生长，而测量的生理参数变化不明显，转录水平差异明显。设施内‘萨米脱’甜樱桃施用含有77 mg硒酸钠的袋装杂草基质，采用两侧和单侧施用，使果实硒含量有显著提高并达到富硒水平，褪黑素含量明显升高。还开展了不同形态硒对甜樱桃生殖生长方面探索工作。总之，这为生产富硒高褪黑素保健型甜樱桃提供重要依据。