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Abstract BackgroundThe La-related proteins (LARPs) are a superfamily of RNA-binding proteins associated with regulation of gene expression. Evidence points to an important role for post-transcriptional control of gene expression in germinating pollen tubes, which could be aided by RNA-binding proteins. ResultsIn this study, a genome-wide investigation of the LARP proteins in eight plant species was performed. The LARP proteins were classified into three families based on a phylogenetic analysis. The gene structure, conserved motifs,cis-acting elements in the promoter, and gene expression profiles were investigated to provide a comprehensive overview of the evolutionary history and potential functions ofZmLARPgenes in maize. Moreover,ZmLARP6c1was specifically expressed in pollen and ZmLARP6c1 was localized to the nucleus and cytoplasm in maize protoplasts. Overexpression ofZmLARP6c1enhanced the percentage pollen germination compared with that of wild-type pollen. In addition, transcriptome profiling analysis revealed that differentially expressed genes includedPABPhomologous genes and genes involved in jasmonic acid and abscisic acid biosynthesis, metabolism, signaling pathways and response in aZmlarp6c1::Dsmutant andZmLARP6c1-overexpression line compared with the corresponding wild type. ConclusionsThe findings provide a basis for further evolutionary and functional analyses, and provide insight into the critical regulatory function ofZmLARP6c1in maize pollen germination. 

Abstract Although DNA methylation primarily represses TEs, it also represses select genes that are methylated in plant body tissues but demethylated by DNA glycosylases (DNGs) in endosperm or pollen. Either one of two DNGs, MATERNAL DEREPRESSION OF R1 (MDR1) or DNG102, is essential for pollen viability in maize. Using single-pollen mRNA sequencing on pollen-segregating mutations in both genes, we identify 58 candidate DNG target genes that account for 11.1% of the wild-type transcriptome but are silent or barely detectable in other tissues. They are unusual in their tendency to lack introns but even more so in their TE-like methylation (teM) in coding DNA. The majority have predicted functions in cell wall modification, and they likely support the rapid tip growth characteristic of pollen tubes. These results suggest a critical role for DNA methylation and demethylation in regulating maize genes with the potential for extremely high expression in pollen but constitutive silencing elsewhere.