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Abstract
Apomixis, a type of asexual reproduction in angiosperms, results in progenies that are genetically identical to the mother plant. It is a highly desirable trait in agriculture due to its potential to preserve heterosis of F1 hybrids through subsequent generations. However, no major crops are apomictic. Deciphering mechanisms underlying apomixis becomes one of the alternatives to engineer self-producing capability into major crops. Parthenogenesis, a major component of apomixis commonly described as the ability to initiate embryo formation from the egg cell without fertilization, also can be valuable in plant breeding for doubled haploid production. Discovery of genes driving parthenogenesis in the natural apomict, Cenchrus ciliaris, has been challenging due to limited genomic resources and technical difficulties in accessing the egg cell expressing parthenogenesis. By conducting laser capture microdissection-based RNA-seq on sexual and apomictic egg apparatus on the day of anthesis, we created a de novo transcriptome with sequence information for the Cenchrus ciliaris egg apparatus, identified transcriptional profiles that distinguish apomictic egg from its sexual counterpart, and suggested functional roles for a few transcription factors in promoting natural parthenogenesis. Our transcriptome data significantly complemented previous gene expression studies and will be an important resource for future research on natural parthenogenesis, as well as inquiries using sexual and apomictic egg cells that extend beyond those of parthenogenesis.