A large and diverse library of glycan-directed monoclonal antibodies (mAbs) was used to determine if plant cell walls are modified by low-gravity conditions encountered during spaceflight. This method called glycome profiling (glycomics) revealed global differences in non-cellulosic cell wall epitopes in
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Abstract Arabidopsis thaliana root extracts recovered from RNA purification columns between seedlings grown on the International Space Station-based Vegetable Production System and paired ground (1-g ) controls. Immunohistochemistry on 11-day-old seedling primary root sections showed that ten of twenty-two mAbs that exhibited spaceflight-induced increases in binding through glycomics, labeled space-grown roots more intensely than those from the ground. The ten mAbs recognized xyloglucan, xylan, and arabinogalactan epitopes. Notably, three xylem-enriched unsubstituted xylan backbone epitopes were more intensely labeled in space-grown roots than in ground-grown roots, suggesting that the spaceflight environment accelerated root secondary cell wall formation. This study highlights the feasibility of glycomics for high-throughput evaluation of cell wall glycans using only root high alkaline extracts from RNA purification columns, and subsequent validation of these results by immunohistochemistry. This approach will benefit plant space biological studies because it extends the analyses possible from the limited amounts of samples returned from spaceflight and help uncover microgravity-induced tissue-specific changes in plant cell walls. -
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Summary Plant lateral organ development is a complex process involving both transcriptional activation and repression mechanisms. The
WOX transcriptional repressorWOX 1/STF , theLEUNIG (LUG ) transcriptional corepressor and theANGUSTIFOLIA 3 (AN 3) transcriptional coactivator play important roles in leaf blade outgrowth and flower development, but how these factors coordinate their activities remains unclear. Here we report physical and genetic interactions among these key regulators of leaf and flower development.We developed a novel
in planta transcriptional activation/repression assay and suggest thatLUG could function as a transcriptional coactivator during leaf blade development.Mt
LUG physically interacts with MtAN 3, and this interaction appears to be required for leaf and flower development. A single amino acid substitution at position 61 in theSNH domain of MtAN 3 protein abolishes its interaction with MtLUG , and its transactivation activity and biological function. Mutations inlug andan3 enhanced each other's mutant phenotypes. Both thelug and thean3 mutations enhanced thewox1 prs leaf and flower phenotypes inArabidopsis .Our findings together suggest that transcriptional repression and activation mediated by the
WOX ,LUG andAN 3 regulators function in concert to promote leaf and flower development, providing novel mechanistic insights into the complex regulation of plant lateral organ development.
