Phylogenetically Distant Genes From Induce Parthenogenesis in Rice.

The combination of apomixis and hybrid production is hailed as the holy grail of agriculture for the ability of apomixis to fix heterosis of F hybrids in succeeding generations, thereby eliminating the need for repeated crosses to produce F hybrids. Apomixis, asexual reproduction through seed, achieves this feat by circumventing two processes that are fundamental to sexual reproduction (meiosis and fertilization) and replacing them with apomeiosis and parthenogenesis, resulting in seeds that are clonal to the maternal parent. Parthenogenesis, embryo development without fertilization, has been genetically engineered in rice, maize, and pearl millet using () transgenes and in rice using the () cDNA sequence when expressed under the control of egg cell-specific promoters. A phylogenetic analysis revealed that genes from monocots cluster within three different clades. The / genes shown to induce parthenogenesis cluster within clade 1 (the ASGR-BBML clade) along with orthologs from other monocot species, such as . For this study, we tested the parthenogenetic potential of three transgenes from , each a member of a different phylogenetic BBM clade. All transgenes were genomic constructs under the control of the DD45 egg cell-specific promoter. All transgenes induced various levels of parthenogenetic embryo development, resulting in viable haploid T seedlings. Poor seed set and lower haploid seed production were characteristics of multiple transgenic lines. The results presented in this study illustrate that further functional characterization of s in zygote/embryo development is warranted.