Project description:There are numerous examples in plants, where certain organs or developmental stages are desiccation tolerant and can withstand extended periods of severe water loss. One prime example are seeds and pollen of many spermatophytes. However, in some plants, also vegetative organs can be desiccation tolerant as for example the tubers of yellow nutsedge (Cyperus esculentus) that also store larger amounts of lipids similar to seeds. Interestingly, the closest relative purple nutsedge (Cyperus rotundus) generates tubers that do not accumulate oil and are not desiccation tolerant. We generated nanoLC-MS/MS-based proteomes of yellow nutsedge in five replicates of four stages of tuber development and compared them to the proteomes of roots and leaves, yielding 2257 distinct protein groups. Our data reveal a striking upregulation of hallmark proteins of seeds in the tubers. A deeper comparison to the tuber proteome of the closest relative purple nutsedge (Cyperus rotundus) and a previously published proteome of Arabidopsis seeds and seedlings indicates that indeed a seed-like proteome was found in yellow but not purple nutsedge. This was further supported by an analysis of the proteome of a lipid-droplet enriched fraction of yellow nutsedge, which also displayed seed-like characteristics. One reason for the differences between the two nutsedge species might be the expression of certain transcription factors homolog to ABSCISIC ACID INSENSITIVE3, WRINKLED1 and LEAFY COTYLEDON1 that drive gene expression in Arabidopsis seed embryos.
Project description:Drought is the prime stressors that land plants have to overcome since their dawn. One strategy that land plants employ is to limit water loss and to transport water via a vascular system, another is to produce desiccation tolerant cells and tissues. In most flowering plants, the latter strategy is limited to seeds and to some extend pollen. Common to desiccation and drought tolerance is the accumulation of small osmolytes and proteins with protective functions. Also common to both strategies is the accumulation of neutral lipids, foremost triacylglycerol (TAG), in cytosolic lipid droplets (LDs) with especially high levels being reached in embryonic tissues. Here, we investigated yellow nutsedge (Cyperus esculentus), a monocot, perennial C4 plant. This species produces stolon-derived underground tubers that can fully desiccate and remain viable for years. Yellow nutsedge stands out, as its tubers store 25-30 % of their dry mass in lipids especially TAG, similar to seeds. We generated nanoLC-MS/MS-based proteomes in five replicates of four stages of tuber development and compared them to the proteomes of roots and leaves, yielding 2257 distinct protein groups. Our data reveal a striking upregulation of hallmark proteins of seeds in the tubers. A deeper comparison to a previously published proteome of Arabidopsis seeds and seedlings indicate that indeed a seed-like proteome was co-opted. This was further supported by an analysis of the proteome of a lipid-droplet enriched fraction of yellow nutsedge, which also displayed seed-like characteristics.