Key Laboratory of Crop Gene Resources and Germplasm Enhancement, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
College of Life and Environmental Science, Minzu University of China, Beijing, 10081, China.
Plant Mol Biol. 2020 Dec;104(6):615-628. doi: 10.1007/s11103-020-01064-1. Epub 2020 Sep 23.
TaPSK5 is a less conserved target of miR164 in wheat encoding a positive regulator of root growth and yield traits that could be used for crop improvement. MicroRNAs (miRNAs) play key roles in regulating plant growth and development by targeting the mRNAs of conserved genes. However, little is known about the roles of less conserved miRNA-targeted genes in plants. In the current study, we identified TaPSK5, encoding a phytosulfokine precursor, as a novel target of miR164. Compared with miR164-targeted NAC transcription factor genes, TaPSK5 is less conserved between monocots and dicots. Expression analysis indicated that TaPSK5 homoeologs were constitutively expressed in wheat tissues, especially young spikes. Overexpression of TaPSK5-D and miR164-resistant TaPSK5-D (r-TaPSK5-D) led to increased primary root growth and grain yield in rice, with the latter having more significant effects. Comparison of the transcriptome between wild-type and r-TaPSK5-D overexpression plants revealed multiple differentially expressed genes involved in hormone signaling, transcription regulation, and reactive oxygen species (ROS) homeostasis. Moreover, we identified three TaPSK5-A haplotypes (TaPSK5-A-Hap1/2/3) and two TaPSK5-B haplotypes (TaPSK5-B-Hap1/2) in core collections of Chinese wheat. Both TaPSK5-A-Hap1 and TaPSK5-B-Hap2 are favorable haplotypes associated with superior yield traits that were under positive selection during wheat breeding. Together, our findings identify miR164-targeted TaPSK5 as a regulator of root growth and yield traits in common wheat with potential applications for the genetic improvement of crops.
TaPSK5 是小麦中 miR164 的一个不太保守的靶标，编码一个根生长和产量性状的正调控因子，可用于作物改良。microRNAs（miRNAs）通过靶向保守基因的 mRNA 在植物生长和发育中发挥关键作用。然而，对于不太保守的 miRNA 靶向基因在植物中的作用知之甚少。在本研究中，我们鉴定了编码植物磺基肽前体的 TaPSK5 是 miR164 的一个新靶标。与 miR164 靶向的 NAC 转录因子基因相比，TaPSK5 在单子叶植物和双子叶植物之间的保守性较低。表达分析表明，TaPSK5 同源基因在小麦组织中持续表达，尤其是幼穗。过表达 TaPSK5-D 和 miR164 抗性 TaPSK5-D（r-TaPSK5-D）导致水稻中主根生长和粒产量增加，后者的影响更为显著。野生型和 r-TaPSK5-D 过表达植株之间的转录组比较显示，多个参与激素信号、转录调控和活性氧（ROS）稳态的差异表达基因。此外，我们在中国小麦核心群体中鉴定了三个 TaPSK5-A 单倍型（TaPSK5-A-Hap1/2/3）和两个 TaPSK5-B 单倍型（TaPSK5-B-Hap1/2）。TaPSK5-A-Hap1 和 TaPSK5-B-Hap2 都是有利的单倍型，与产量性状优良有关，在小麦育种过程中受到正选择。总之，我们的研究结果表明，miR164 靶向的 TaPSK5 是普通小麦根生长和产量性状的调控因子，具有作物遗传改良的潜力。
