背景:在苜蓿(紫花苜蓿)中,干扰亚种的共存(即苜蓿,falcata和coheulea)的特征在于不同的倍性水平(二倍体和四倍体)以及能够产生未还原(2n)配子的减数分裂突变体的发生,已被有效地组合以建立新的多倍体。有关牧草质量和产量的大量农艺数据为多倍体化的实际利益提供了透彻的见解。然而,关于基因表达和调控的许多潜在分子机制仍未完全探索。在这项研究中,我们旨在通过检查叶片和生殖组织的转录组概况来解决这个差距,对应于花药和雌蕊,在不同时间点从属于双侧性多倍体化产生的后代的二倍体和四倍体紫花苜蓿个体中取样(dBSP和tBSP,分别)和源自单侧性多倍体化(tUSP)的四倍体个体。
结果:考虑到花药和雌蕊在减少和未减少配子形成中的关键作用,我们首先分析了生殖组织在不同阶段的转录谱,无论倍性水平和样品的来源。通过使用和组合三种不同的分析方法,即加权基因共表达网络分析(WGCNA),tau(τ)分析,和差异表达基因(DEGs)分析,我们确定了一组强大的基因和转录因子可能参与男性孢子发生和配子发生过程,特别是在穿越时,call的合成,和外部形成。随后,我们在同一花期评估,归因于倍性水平的差异(tBSP与dBSP)或原点(tBSP与tUSP)的样品,导致倍性和亲本特异性基因的鉴定。这样,我们确定,例如,在tBSP和dBSP之间的比较中,在花蕾中特异性上调和下调的基因,这可以解释前者与后者材料相比生育力降低。
结论:虽然这项研究主要作为转录组水平的广泛研究,提供的数据不仅可以代表科学界宝贵的原始资产,而且可以为苜蓿的功能分析提供完全可利用的基因组资源。
BACKGROUND: In alfalfa (Medicago sativa), the coexistence of interfertile subspecies (i.e. sativa, falcata and coerulea) characterized by different ploidy levels (diploidy and tetraploidy) and the occurrence of meiotic mutants capable of producing unreduced (2n) gametes, have been efficiently combined for the establishment of new polyploids. The wealth of agronomic data concerning forage quality and yield provides a thorough insight into the practical benefits of polyploidization. However, many of the underlying molecular mechanisms regarding gene expression and regulation remained completely unexplored. In this study, we aimed to address this gap by examining the transcriptome profiles of leaves and reproductive tissues, corresponding to anthers and pistils, sampled at different time points from diploid and tetraploid Medicago sativa individuals belonging to progenies produced by bilateral sexual polyploidization (dBSP and tBSP, respectively) and tetraploid individuals stemmed from unilateral sexual polyploidization (tUSP).
RESULTS: Considering the crucial role played by anthers and pistils in the reduced and unreduced gametes formation, we firstly analyzed the transcriptional profiles of the reproductive tissues at different stages, regardless of the ploidy level and the origin of the samples. By using and combining three different analytical methodologies, namely weighted-gene co-expression network analysis (WGCNA), tau (τ) analysis, and differentially expressed genes (DEGs) analysis, we identified a robust set of genes and transcription factors potentially involved in both male sporogenesis and gametogenesis processes, particularly in crossing-over, callose synthesis, and exine formation. Subsequently, we assessed at the same floral stage, the differences attributable to the ploidy level (tBSP vs. dBSP) or the origin (tBSP vs. tUSP) of the samples, leading to the identification of ploidy and parent-specific genes. In this way, we identified, for example, genes that are specifically upregulated and downregulated in flower buds in the comparison between tBSP and dBSP, which could explain the reduced fertility of the former compared to the latter materials.
CONCLUSIONS: While this study primarily functions as an extensive investigation at the transcriptomic level, the data provided could represent not only a valuable original asset for the scientific community but also a fully exploitable genomic resource for functional analyses in alfalfa.