Key Laboratory of Horticultural Plant Growth, Development and Quality improvement, Ministry of Agriculture, Department of Horticulture, Zhejiang University, Hangzhou 310058, PR China.
J Exp Bot. 2012 Oct;63(16):5751-61. doi: 10.1093/jxb/ers224. Epub 2012 Sep 3.
One of the main characteristics of tomato (Solanum lycopersicum) fruit ripening is a massive accumulation of carotenoids (mainly lycopene), which may contribute to the nutrient quality of tomato fruit and its role in chemoprevention. Previous studies have shown that ethylene (ET) plays a central role in promoting fruit ripening. In this study, the role of jasmonic acid (JA) in controlling lycopene accumulation in tomato fruits was analysed by measuring fruit lycopene content and the expression levels of lycopene biosynthetic genes in JA-deficient mutants (spr2 and def1) and a 35S::prosystemin transgenic line (35S::prosys) with increased JA levels and constitutive JA signalling. The lycopene content was significantly decreased in the fruits of spr2 and def1, but was enhanced in 35S::prosys fruits. Simultaneously, the expression of lycopene biosynthetic genes followed a similar trend. Lycopene synthesis in methyl jasmonate (MeJA) vapour-treated fruits showed an inverted U-shaped dose response, which significantly enhanced the fruit lycopene content and restored lycopene accumulation in spr2 and def1 at a concentration of 0.5 µM. The results indicated that JA plays a positive role in lycopene biosynthesis. In addition, the role of ET in JA-induced lycopene accumulation was also examined. Ethylene production in tomato fruits was depressed in spr2 and def1 while it increased in 35S::prosys. However, the exogenous application of MeJA to Never ripe (Nr), the ET-insensitive mutant, significantly promoted lycopene accumulation, as well as the expression of lycopene biosynthetic genes. Based on these results, it is proposed that JA might function independently of ethylene to promote lycopene biosynthesis in tomato fruits.
番茄（Solanum lycopersicum）果实成熟的一个主要特征是类胡萝卜素（主要是番茄红素）的大量积累，这可能有助于提高番茄果实的营养价值及其在化学预防中的作用。先前的研究表明，乙烯（ET）在促进果实成熟中起核心作用。在这项研究中，通过测量果实番茄红素含量和番茄红素生物合成基因的表达水平，分析了茉莉酸（JA）在控制番茄果实中番茄红素积累中的作用，这些基因在 JA 缺陷突变体（spr2 和 def1）和一个具有增加 JA 水平和组成型 JA 信号的 35S::prosystemin 转基因系（35S::prosys）中进行了分析。spr2 和 def1 果实中的番茄红素含量显著降低，但 35S::prosys 果实中的番茄红素含量增加。同时，番茄红素生物合成基因的表达也呈现出相似的趋势。茉莉酸甲酯（MeJA）蒸气处理果实中的番茄红素合成呈倒 U 型剂量反应，在 0.5 µM 浓度下，显著提高了果实番茄红素含量，并恢复了 spr2 和 def1 中番茄红素的积累。结果表明，JA 在番茄红素生物合成中发挥积极作用。此外，还研究了 ET 在 JA 诱导的番茄红素积累中的作用。spr2 和 def1 果实中的乙烯生成受到抑制，而 35S::prosys 中的乙烯生成增加。然而，MeJA 外源应用于乙烯不敏感突变体 Never ripe（Nr）显著促进了番茄红素的积累，以及番茄红素生物合成基因的表达。基于这些结果，提出 JA 可能独立于乙烯作用于促进番茄果实中的番茄红素生物合成。
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