Abstract
Background: Apomixis is mainly used to maintain the heterosis, stability, and consistency of crops. Its main advantage is to reduce the costs of seed production and shorten the breeding process. In the field of hybrid breeding, apomixis has been referred to as the "asexual revolution" and has realized a new green revolution.Apomixis is mainly used to maintain the heterosis, stability, and consistency of crops. Its main advantage is to reduce the costs of seed production and shorten the breeding process. In the field of hybrid breeding, apomixis has been referred to as the "asexual revolution" and has realized a new green revolution. Kentucky bluegrass (Poa pratensis) is a natural apomictic species that mainly exhibits facultative apospory. Its main feature is that the somatic nucellar cells bypass meiosis and double fertilization to form unreduced embryos, and the development of the endosperm requires pseudogamy. Although apomixis is of great significance in breeding, the genetic control of apomixis remains unclear. Therefore, we report the results of a global gene expression analysis of wild germplasm materials of Kentucky bluegrass spikelets in Gansu province of China, exhibiting significant differences in apomictic rates to identify the genes, biological processes, and molecular functions related to apomixis.Result: At four reproductive periods, there were 5400 differentially expressed genes (DEGs) between the two genotypes, including 2476 downregulated and 2823 upregulated genes. Further analysis of the gene functions, pathways, expression patterns, networks, and transcription factors (TFs) showed that the occurrence of apomixis in Kentucky bluegrass was related to changes in the time- and space-related expression of genes associated with sexual reproduction, which led to disordered sexual reproduction and thus the production of offspring by apomixis. Conclusion: At the transcriptional level, the genesis and development of apomixis was regulated by TFs. It also involved the coexpression of many genes associated with disordered meiosis, hormone signal transduction, embryonic development, stress response pathways, and epigenetics. We also verified these 16 DEGs by real-time quantitative PCR. The expression results were basically consistent with the transcriptome expression profile, indicating that the transcriptome data were reliable. The results of this study may provide a theoretical basis for revealing the mechanism of occurrence and development of apomixis in Kentucky bluegrass.