Leibniz-Institut für Pflanzengenetik und Kulturpflanzenforschung (IPK), D-06466 Gatersleben, Germany.
Plant J. 2011 Feb;65(4):517-31. doi: 10.1111/j.1365-313X.2010.04450.x. Epub 2011 Jan 14.
Selfed and crossed seeds of two homozygous Vicia faba lines served as models for the analysis of the physiological and molecular mechanisms underlying embryo heterosis. Profiles of transcripts, metabolites and seed contents of developing embryos were analysed to compare the means of reciprocally crossed and selfed seeds growing on the same mother plants. The mean weight of mature hybrid seeds was demonstrably higher, revealing mid-parent heterosis. Hybrid embryos exhibited a prolonged early phase of development and delayed onset of storage activity. Accordingly, transcript profiling indicates stimulation of cell proliferation, an effect, which is potentially mediated by activation of auxin functions within a framework of growth-related transcription factors. At the transcript level, activated cell proliferation increased assimilate uptake activity and thereby seed sink strength. This situation might finally lead to the increased size of the hybrid seeds. We conclude that hybrid seeds are characterised by accelerated growth during early development, which increases storage capacity and leads to higher metabolic fluxes. These needs are, at least partially, met by increased assimilate uptake capacity. The stimulated growth of hybrid seeds shifted metabolite profiles and potentially depleted available pools. Such metabolic shifts are most likely secondary effects resulting from the higher storage capacity of hybrid seeds, a heterotic feature, which is itself established very early in seed development.
自交和杂交的两个纯合蚕豆品系的种子被用作分析胚胎杂种优势潜在生理和分子机制的模型。分析了发育中胚胎的转录本、代谢物和种子含量的图谱，以比较在同一母株上生长的相互杂交和自交种子的平均值。成熟杂种种子的平均重量明显更高，表现出中亲杂种优势。杂种胚胎表现出早期发育的延长和储存活性的延迟开始。因此，转录谱分析表明细胞增殖的刺激，这种作用可能通过在与生长相关的转录因子框架内激活生长素功能来介导。在转录水平上，激活的细胞增殖增加了同化产物摄取活性，从而增加了种子库的强度。这种情况最终可能导致杂种种子的增大。我们得出结论，杂种种子的特征是在早期发育过程中加速生长，从而增加储存能力并导致更高的代谢通量。这些需求至少部分通过增加同化产物摄取能力来满足。杂种种子的生长刺激改变了代谢物图谱，并可能耗尽了可用的库。这种代谢变化很可能是杂种种子更高储存能力的次生效应，这是一种杂种优势特征，在种子发育的早期就已经建立。
