Department of Horticulture, Zhejiang University, Hangzhou, People's Republic of China.
PLoS One. 2013 Jul 29;8(7):e70080. doi: 10.1371/journal.pone.0070080. Print 2013.
Fruit set of plants largely depends on the biosynthesis and crosstalk of phytohormones. To date the role of cytokinins (CKs) in the fruit development is less understood. Here, we showed that parthenocarpic fruit could be induced by 1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU, an active CK) in tomato (Solanumlycopersicum cv. Micro-Tom). The fresh weight of CPPU-induced parthenocarpic fruits was comparable with that induced by GA3. Importantly, CPPU-induced parthenocarpy was found to be compromised by simultaneous application of paclobutrazol (a GA biosynthesis inhibitor), and this effect could be restored by exogenous GA3. Like pollination, CPPU-induced fruit showed enhanced accumulation of GA1+3 and indole-3-acetic (IAA), which were accompanied by elevated expression of GA biosynthesis genes like SlGPS, SlGA20ox1, SlGA20ox2 and SlGA3ox1, and IAA biosynthesis gene ToFZY. Elevated GAs level in CPPU-induced fruits was also associated with down-regulation of GA inactivation genes, namely SlGA2ox1,2,3,4,5 in comparison with untreated control. These results suggested that CKs may induce parthenocarpy in tomato partially through modulation of GA and IAA metabolisms.
植物的结实很大程度上取决于植物激素的生物合成和相互作用。迄今为止，细胞分裂素（CKs）在果实发育中的作用还不太清楚。在这里，我们表明，1-（2-氯-4-吡啶基）-3-苯基脲（CPPU，一种活性 CK）可以在番茄（Solanumlycopersicum cv. Micro-Tom）中诱导单性结实果实。CPPU 诱导的单性结实果实的鲜重与 GA3 诱导的果实相当。重要的是，同时应用多效唑（一种 GA 生物合成抑制剂）会削弱 CPPU 诱导的单性结实，而外源 GA3 可以恢复这种效应。与授粉一样，CPPU 诱导的果实表现出 GA1+3 和吲哚-3-乙酸（IAA）的积累增强，这伴随着 GA 生物合成基因如 SlGPS、SlGA20ox1、SlGA20ox2 和 SlGA3ox1 以及 IAA 生物合成基因 ToFZY 的表达升高。与未处理的对照相比，CPPU 诱导的果实中 GA 失活基因 SlGA2ox1、2、3、4、5 的下调也与升高的 GAs 水平有关。这些结果表明，CKs 可能通过调节 GA 和 IAA 代谢来部分诱导番茄的单性结实。
