Table_1_Identification of Flowering Regulatory Networks and Hub Genes Expressed in the Leaves of Elymus sibiricus L. Using Comparative Transcriptome Analysis.XLSX

Flowering is a significant stage from vegetative growth to reproductive growth in higher plants, which impacts the biomass and seed yield. To reveal the flowering time variations and identify the flowering regulatory networks and hub genes in Elymus sibiricus, we measured the booting, heading, and flowering times of 66 E. sibiricus accessions. The booting, heading, and flowering times varied from 136 to 188, 142 to 194, and 148 to 201 days, respectively. The difference in flowering time between the earliest- and the last-flowering accessions was 53 days. Furthermore, transcriptome analyses were performed at the three developmental stages of six accessions with contrasting flowering times. A total of 3,526 differentially expressed genes (DEGs) were predicted and 72 candidate genes were identified, including transcription factors, known flowering genes, and plant hormone-related genes. Among them, four candidate genes (LATE, GA2OX6, FAR3, and MFT1) were significantly upregulated in late-flowering accessions. LIMYB, PEX19, GWD3, BOR7, PMEI28, LRR, and AIRP2 were identified as hub genes in the turquoise and blue modules which were related to the development time of flowering by weighted gene co-expression network analysis (WGCNA). A single-nucleotide polymorphism (SNP) of LIMYB found by multiple sequence alignment may cause late flowering. The expression pattern of flowering candidate genes was verified in eight flowering promoters (CRY, COL, FPF1, Hd3, GID1, FLK, VIN3, and FPA) and four flowering suppressors (CCA1, ELF3, Ghd7, and COL4) under drought and salt stress by qRT-PCR. The results suggested that drought and salt stress activated the flowering regulation pathways to some extent. The findings of the present study lay a foundation for the functional verification of flowering genes and breeding of new varieties of early- and late-flowering E. sibiricus.

开花是高等植物从营养生长阶段过渡到生殖生长阶段的重要阶段，对生物量和种子产量产生影响。为揭示Elymus sibiricus的开花时间变异，并识别开花调控网络和关键基因，我们测量了66个E. sibiricus品种的抽穗、拔节和开花时间。抽穗、拔节和开花时间分别为136至188天、142至194天和148至201天。最早和最晚开花品种的开花时间差异为53天。此外，对具有不同开花时间的六个品种在三个发育阶段进行了转录组分析。共预测出3,526个差异表达基因（DEGs），并确定了72个候选基因，包括转录因子、已知开花基因和植物激素相关基因。其中，四个候选基因（LATE、GA2OX6、FAR3和MFT1）在晚开花品种中显著上调。通过加权基因共表达网络分析（WGCNA），LIMYB、PEX19、GWD3、BOR7、PMEI28、LRR和AIRP2被鉴定为与开花发育时间相关的 turquoise 和 blue 模块的核心基因。通过多重序列比对发现的LIMYB单核苷酸多态性（SNP）可能导致晚开花。通过qRT-PCR验证了开花候选基因在八个开花促进因子（CRY、COL、FPF1、Hd3、GID1、FLK、VIN3和FPA）和四个开花抑制因子（CCA1、ELF3、Ghd7和COL4）的表达模式，在干旱和盐胁迫条件下。结果提示，干旱和盐胁迫在一定程度上激活了开花调控途径。本研究的结果为开花基因的功能验证和晚开花及早开花E. sibiricus新品种的育种奠定了基础。