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Creators/Authors contains: "Char, Si Nian"

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  1. Abstract

    Historically, xenia effects were hypothesized to be unique genetic contributions of pollen to seed phenotype, but most examples represent standard complementation of Mendelian traits. We identified the imprinteddosage-effect defective1(ded1) locus in maize (Zea mays) as a paternal regulator of seed size and development. Hypomorphic alleles show a 5–10% seed weight reduction whended1is transmitted through the male, while homozygous mutants are defective with a 70–90% seed weight reduction.Ded1encodes an R2R3-MYB transcription factor expressed specifically during early endosperm development with paternal allele bias. DED1 directly activates early endosperm genes and endosperm adjacent to scutellum cell layer genes, while directly repressing late grain-fill genes. These results demonstrate xenia as originally defined: Imprinting ofDed1causes the paternal allele to set the pace of endosperm development thereby influencing grain set and size.

     
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  2. Mittelsten Scheid, Ortrun (Ed.)
    The post-translational addition of SUMO plays essential roles in numerous eukaryotic processes including cell division, transcription, chromatin organization, DNA repair, and stress defense through its selective conjugation to numerous targets. One prominent plant SUMO ligase is METHYL METHANESULFONATE-SENSITIVE (MMS)-21/HIGH-PLOIDY (HPY)-2/NON-SMC-ELEMENT (NSE)-2, which has been connected genetically to development and endoreduplication. Here, we describe the potential functions of MMS21 through a collection of UniformMu and CRISPR/Cas9 mutants in maize ( Zea mays ) that display either seed lethality or substantially compromised pollen germination and seed/vegetative development. RNA-seq analyses of leaves, embryos, and endosperm from mms21 plants revealed a substantial dysregulation of the maize transcriptome, including the ectopic expression of seed storage protein mRNAs in leaves and altered accumulation of mRNAs associated with DNA repair and chromatin dynamics. Interaction studies demonstrated that MMS21 associates in the nucleus with the NSE4 and STRUCTURAL MAINTENANCE OF CHROMOSOMES (SMC)-5 components of the chromatin organizer SMC5/6 complex, with in vitro assays confirming that MMS21 will SUMOylate SMC5. Comet assays measuring genome integrity, sensitivity to DNA-damaging agents, and protein versus mRNA abundance comparisons implicated MMS21 in chromatin stability and transcriptional controls on proteome balance. Taken together, we propose that MMS21-directed SUMOylation of the SMC5/6 complex and other targets enables proper gene expression by influencing chromatin structure. 
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  5. Summary

    SWEETs play important roles in intercellular sugar transport. Induction of SWEET sugar transporters by Transcription Activator‐Like effectors (TALe) ofXanthomonasssp. is key for virulence in rice, cassava and cotton.

    We identified OsSWEET11b with roles in male fertility and potential bacterial blight (BB) susceptibility in rice. While singleossweet11aor11bmutants were fertile, double mutants were sterile. As clade III SWEETs can transport gibberellin (GA), a key hormone for spikelet fertility, sterility and BB susceptibility might be explained by GA transport deficiencies. However, in contrast with the Arabidopsis homologues, OsSWEET11b did not mediate detectable GA transport. Fertility and susceptibility therefore are likely to depend on sucrose transport activity.

    Ectopic induction ofOsSWEET11bby designer TALe enabled TALe‐freeXanthomonas oryzaepv.oryzae(Xoo) to cause disease, identifyingOsSWEET11bas a potential BB susceptibility gene and demonstrating that the induction of host sucrose uniporter activity is key to virulence ofXoo. Notably, only three of six clade III SWEETs are targeted by knownXoostrains from Asia and Africa.

    The identification of OsSWEET11b is relevant for fertility and for protecting rice against emergingXoostrains that targetOsSWEET11b.

     
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