Myo‐inositol hexakisphosphate, isolated from female gametophyte tissue of loblolly pine, inhibits growth of early‐stage somatic embryos

Summary •Myo-inositol hexakisphosphate (InsP6), abundant in animals and plants, is well known for its anticancer activity. However, many aspects of InsP6 function in plants remain undefined. We now report the first evidence that InsP6 can inhibit cellular proliferation in plants under growth conditions where phosphorus is not limited. •A highly anionic molecule inhibitory to early-stage somatic embryo growth of loblolly pine (LP) was purified chromatographically from late-stage LP female gametophytes (FGs), and then characterized structurally using mass spectrometry (MS) and nuclear magnetic resonance (NMR) analyses. •Exact mass and mass spectrometry-mass spectrometry (MS-MS) fragmentation identified the bioactive molecule as an inositol hexakisphosphate. It was then identified as the myo-isomer (i.e. InsP6) on the basis of 1H-, 31P- and 13C-NMR, 1H-1H correlation spectroscopy (COSY), 1H-31P heteronuclear single quantum correlation (HSQC) and 1H-13C HSQC. Topical application of InsP6 to early-stage somatic embryos indeed inhibits embryonic growth. •Recently evidence has begun to emerge that InsP6 may also play a regulatory role in plant cells. We anticipate that our findings will help to stimulate additional investigations aimed at elucidating the roles of inositol phosphates in cellular growth and development in plants.