One of the biggest challenges in clonal propagation of grapevine (Vitis vinifera) is difficulty of rooting. Adventitious root initiation and development are the critical steps in the cutting and layering process of grapevine, but the molecular mechanism of these processes remains unclear. Previous reports have found that microRNA (miRNA)-encoded peptides (miPEPs) can regulate plant root development by increasing the transcription of their corresponding primary miRNA. Here, we report the role of a miPEP in increasing adventitious root formation in grapevine. In this study, we performed a global analysis of miPEPs in grapevine and characterized the function of vvi-miPEP171d1, a functional, small peptide encoded by primary-miR171d. There were three small open reading frames in the 500-bp upstream sequence of pre-miR171d. One of them encoded a small peptide, vvi-miPEP171d1, which could increase the transcription of vvi-MIR171d. Exogenous application of vvi-miPEP171d1 to grape tissue culture plantlets promoted adventitious root development by activating the expression of vvi-MIR171d. Interestingly, neither exogenous application of the vvi-miPEP171d1 peptide nor overexpression of the vvi-miPEP171d1 coding sequence resulted in phenotypic changes in Arabidopsis (Arabidopsis thaliana). Similarly, application of synthetic ath-miPEP171c, the small peptide encoded by the Arabidopsis ortholog of vvi-MIR171d, inhibited the growth of primary roots and induced the early initiation of lateral and adventitious roots in Arabidopsis, while it had no effect on grape root development. Our findings reveal that miPEP171d1 regulates root development by promoting vvi-MIR171d expression in a species-specific manner, further enriching the theoretical research into miPEPs.

一个在葡萄无性繁殖的最大挑战（葡萄）很难生根。不定根的引发和发育是葡萄切割和成层过程中的关键步骤，但这些过程的分子机制仍不清楚。先前的报告发现，microRNA（miRNA）编码的肽（miPEP）可以通过增加其相应的主要miRNA的转录来调节植物根系的发育。在这里，我们报道了miPEP在增加葡萄不定根形成中的作用。在这项研究中，我们对葡萄中的miPEPs进行了全面分析，并鉴定了vvi-miPEP171d1（由原miR171d编码的功能性小肽）的功能。pre-miR171d的500 bp上游序列中有3个小的开放阅读框。其中一个编码了一种小肽vvi-miPEP171d1，该肽可以增加vvi-MIR171d。VVI-miPEP171d1的外源性应用以葡萄的组织培养的小植株通过激活vvi-的表达促进不定根发育MIR171d。有趣的是，既不外源应用vvi-miPEP171d1肽也不过度表达vvi-miPEP171d1编码序列不会导致拟南芥（Arabidopsis thaliana）的表型变化。同样，使用合成的ath-miPEP171c（由vvi-MIR171d的拟南芥直系同源基因编码的小肽）抑制拟南芥的初生根生长并诱导其侧生和不定根的早期萌发，而对葡萄根的发育没有影响。我们的发现表明，miPEP171d1通过促进vvi-MIR171d以物种特异性方式表达，进一步丰富了miPEP的理论研究。