氮(N)对甜菜(BetavulgarisL.)至关重要,一种对N要求很高的糖作物。这项研究调查了形态学,亚细胞,和microRNA调节的响应甜菜根对低氮(LN)胁迫(0.5mmol/LN),以更好地了解N的感知,摄取,以及在这个物种中的利用。结果表明,LN导致根系干重下降,N积累,和N干物质生产效率,以及细胞壁和细胞膜的损伤和细胞器数量(特别是线粒体)的减少。同时,与对照组相比,LN暴露7d后,甜菜的根长(7.2%)和分支数(29.2%)增加,根表面积(6.14%)和根体积(6.23%)减少(5mmol/LN)。通过qRT-PCR对6种随机选择的microRNA进行了转录组学分析。在LN处理下,我们在甜菜根中鉴定了22种差异表达的microRNAs(DEM)。它们主要富含与结合相关的功能(1125),离子结合(641),细胞内(437)和细胞内部分(428),和细胞器(350),与淀粉和蔗糖代谢有关,酪氨酸代谢,嘧啶代谢,氨基糖和核苷酸糖代谢,和异喹啉生物碱的生物合成,如GO和KEGG分析所示。其中,上调的miR156a,具有保守的序列,被确定为潜在靶向和调节squamosa启动子结合样蛋白的关键DEM(SPLs,104889216和104897537)通过microRNA-mRNA网络。miR156a(MIR)的过表达促进了转基因拟南芥的根生长,增加长度,表面积,和音量。相比之下,沉默miR156a(STTM)具有相反的效果。值得注意的是,STTM品系的鲜根重量下降了45.6%,虽然它在MIR系列中增加了27.4%,与野生型(WT)相比。可以推断microRNA,特别是miR156,在甜菜根的发育和适应LN条件中起着至关重要的作用。它们可能通过网络调节促进对N缺乏的积极反应,使甜菜根能够从环境中吸收营养并维持其重要的生命过程。
Nitrogen (N) is essential for sugar beet (Beta vulgaris L.), a highly N-demanding sugar crop. This study investigated the morphological, subcellular, and microRNA-regulated responses of sugar beet roots to low N (LN) stress (0.5 mmol/L N) to better understand the N perception, uptake, and utilization in this species. The results showed that LN led to decreased dry weight of roots, N accumulation, and N dry matter production efficiency, along with damage to cell walls and membranes and a reduction in organelle numbers (particularly mitochondria). Meanwhile, there was an increase in root length (7.2%) and branch numbers (29.2%) and a decrease in root surface area (6.14%) and root volume (6.23%) in sugar beet after 7 d of LN exposure compared to the control (5 mmol/L N). Transcriptomics analysis was confirmed by qRT-PCR for 6 randomly selected microRNAs, and we identified 22 differentially expressed microRNAs (DEMs) in beet root under LN treatment. They were primarily enriched in functions related to binding (1125), ion binding (641), intracellular (437) and intracellular parts (428), and organelles (350) and associated with starch and sucrose metabolism, tyrosine metabolism, pyrimidine metabolism, amino sugar and nucleotide sugar metabolism, and isoquinoline alkaloid biosynthesis, as indicated by the GO and KEGG analyses. Among them, the upregulated miR156a, with conserved sequences, was identified as a key DEM that potentially targets and regulates squamosa promoter-binding-like proteins (SPLs, 104889216 and 104897537) through the microRNA-mRNA network. Overexpression of miR156a (MIR) promoted root growth in transgenic Arabidopsis, increasing the length, surface area, and volume. In contrast, silencing miR156a (STTM) had the opposite effect. Notably, the fresh root weight decreased by 45.6% in STTM lines, while it increased by 27.4% in MIR lines, compared to the wild type (WT). It can be inferred that microRNAs, especially miR156, play crucial roles in sugar beet root\'s development and acclimation to LN conditions. They likely facilitate active responses to N deficiency through network regulation, enabling beet roots to take up nutrients from the environment and sustain their vital life processes.