National Engineering Laboratory for Crop Molecular Breeding, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Engineering Research Center of Biomass Resources and Environment and CAS Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China.
Mol Plant. 2018 Jun 4;11(6):806-814. doi: 10.1016/j.molp.2018.03.013. Epub 2018 Mar 27.
Lodging under nitrogen (N)-luxury conditions substantially reduces crop yield and seed quality. However, the molecular mechanisms of plant lodging resistance remain largely unclear, especially in maize. We report here that the expression of ZmmiR528, a monocot-specific microRNA, is induced by N luxury but reduced by N deficiency. We show by the thioacidolysis and acetyl bromide analysis that N luxury significantly reduces the generation of H, G, and S monomers of the lignin as well as its total content in maize shoots. We further demonstrate that ZmLACCASE3 (ZmLAC3) and ZmLACCASE5 (ZmLAC5), which encode the copper-containing laccases, are the targets of ZmmiR528. In situ hybridization showed that ZmmiR528 is mainly expressed in maize vascular tissues. Knockdown of ZmmiR528 or overexpression of ZmLAC3 significantly increased the lignin content and rind penetrometer resistance of maize stems. In contrast, transgenic maize plants overexpressing ZmmiR528 had reduced lignin content and rind penetrometer resistance and were prone to lodging under N-luxury conditions. RNA-sequencing analysis revealed that ZmPAL7 and ZmPAL8 are upregulated in transgenic maize lines downregulating ZmmiR528. Under N-luxury conditions, the expression levels of ZmPALs were much higher in ZmmiR528-knockdown lines than in the wild type and transgenic maize lines overexpressing ZmmiR528. Taken together, these results indicate that, by regulating the expression of ZmLAC3 and ZmLAC5, ZmmiR528 affects maize lodging resistance under N-luxury conditions.
氮(N)奢侈条件下的倒伏会显著降低作物产量和种子质量。然而,植物抗倒伏的分子机制在很大程度上仍不清楚,尤其是在玉米中。我们在此报告,单子叶植物特异性 microRNA ZmmiR528 的表达受 N 奢侈诱导,但受 N 缺乏抑制。通过硫代酸解和乙酰溴分析,我们表明 N 奢侈显著降低了玉米地上部木质素的 H、G 和 S 单体以及其总含量的产生。我们进一步证明,编码含铜漆酶的 ZmLACCASE3(ZmLAC3)和 ZmLACCASE5(ZmLAC5)是 ZmmiR528 的靶标。原位杂交表明,ZmmiR528 主要在玉米维管束组织中表达。ZmmiR528 的敲低或 ZmLAC3 的过表达显著增加了玉米茎的木质素含量和果皮穿透阻力。相比之下,过表达 ZmmiR528 的转基因玉米植株木质素含量和果皮穿透阻力降低,在 N 奢侈条件下易倒伏。RNA-seq 分析表明,ZmPAL7 和 ZmPAL8 在下调 ZmmiR528 的转基因玉米系中上调。在 N 奢侈条件下,ZmPALs 的表达水平在 ZmmiR528 敲低系中比在野生型和过表达 ZmmiR528 的转基因玉米系中高得多。综上所述,这些结果表明,通过调节 ZmLAC3 和 ZmLAC5 的表达,ZmmiR528 影响 N 奢侈条件下玉米的抗倒伏性。