AUTHOR=Chahal Lovepreet Singh , Conner Joann A. , Ozias-Akins Peggy 

TITLE=Phylogenetically Distant BABY BOOM Genes From Setaria italica Induce Parthenogenesis in Rice

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.863908

DOI=10.3389/fpls.2022.863908

ISSN=1664-462X

ABSTRACT=<p>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<sub>1</sub> hybrids in succeeding generations, thereby eliminating the need for repeated crosses to produce F<sub>1</sub> 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 <italic>PsASGR-BABY BOOM-like</italic> (<italic>PsASGR-BBML</italic>) transgenes and in rice using the <italic>OsBABY BOOM1</italic> (<italic>OsBBM1</italic>) cDNA sequence when expressed under the control of egg cell-specific promoters. A phylogenetic analysis revealed that <italic>BABY BOOM (BBM)/BBML</italic> genes from monocots cluster within three different clades. The <italic>BBM</italic>/<italic>BBML</italic> genes shown to induce parthenogenesis cluster within clade 1 (the ASGR-BBML clade) along with orthologs from other monocot species, such as <italic>Setaria italica</italic>. For this study, we tested the parthenogenetic potential of three <italic>BBM</italic> transgenes from <italic>S. italica</italic>, each a member of a different phylogenetic BBM clade. All transgenes were genomic constructs under the control of the <italic>At</italic>DD45 egg cell-specific promoter. All <italic>SiBBM</italic> transgenes induced various levels of parthenogenetic embryo development, resulting in viable haploid T<sub>1</sub> 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 <italic>BBM</italic>s in zygote/embryo development is warranted.</p>