Liu Jianlong, Zhai Rui, Liu Fengxia, Zhao Yingxiao, Wang Huibin, Liu Lulu, Yang Chengquan, Wang Zhigang, Ma Fengwang, Xu Lingfei
College of Horticulture, Northwest A&F University, Yangling, China.
Front Plant Sci. 2018 Jul 4;9:946. doi: 10.3389/fpls.2018.00946. eCollection 2018.
Parthenocarpy, the production of seedless fruit without fertilization, has a variety of valuable qualities, especially for self-incompatible species, such as pear. To explore whether melatonin (MT) induces parthenocarpy, we used 'Starkrimson' pear as a material for morphological observations. According to our results, exogenous MT promoted the expansion and division of the mesocarp cells in a manner similar to hand pollination. However, the seeds of exogenous MT-treated fruit were undeveloped and aborted later in the fruit-setting stage. To further investigate how MT induced parthenocarpy, we studied changes of related hormones in the ovaries and found that MT significantly increased the contents of the gibberellins (GAs) GA and GA. Thus, paclobutrazol (PAC), a GA-biosynthesis inhibitor, was used to study the relationship between GAs and MT. In addition, spraying MT after treatment with PAC did not increase GA content nor lead to parthenocarpy. Through a transcriptome analysis, we discovered that MT can cause significant upregulation of and downregulation of . However, no significant difference was observed in compared with the control after PAC and MT applications. Thus, MT induces parthenocarpy by promoting GA biosynthesis along with cell division and mesocarp expansion in pear.
单性结实，即未受精产生无籽果实，具有多种宝贵特性，尤其对于自交不亲和物种，如梨而言。为探究褪黑素（MT）是否诱导单性结实，我们以‘斯塔克瑞姆森’梨为材料进行形态学观察。根据我们的结果，外源MT以类似于人工授粉的方式促进了中果皮细胞的扩展和分裂。然而，外源MT处理果实的种子未发育，并在坐果后期败育。为进一步研究MT如何诱导单性结实，我们研究了子房相关激素的变化，发现MT显著增加了赤霉素（GAs）GA 和GA 的含量。因此，使用多效唑（PAC），一种GA生物合成抑制剂，来研究GAs与MT之间的关系。此外，在PAC处理后喷施MT既未增加GA含量，也未导致单性结实。通过转录组分析，我们发现MT可导致 显著上调和 下调。然而，在PAC和MT处理后，与对照相比， 未观察到显著差异。因此，MT通过促进GA生物合成以及梨的细胞分裂和中果皮扩展来诱导单性结实。
