Disruption of endosperm development is a major cause of hybrid seed inviability between Mimulus guttatus and Mimulus nudatus

作者：Oneal Elen^*; Willis John H; Franks Robert G

来源：NEW PHYTOLOGIST, 2016, 210(3): 1107-1120.

DOI：10.1111/nph.13842

• endosperm
• hybrid inviability
• Mimulus guttatus (monkeyflower)
• pollen-pistil interactions
• postzygotic isolation
• seed development

Divergence of developmental mechanisms within populations could lead to hybrid developmental failure, and might be a factor driving speciation in angiosperms. We investigate patterns of endosperm and embryo development in Mimulus guttatus and the closely related, serpentine endemic Mimulusnudatus, and compare them to those of reciprocal hybrid seed. We address whether disruption in hybrid seed development is the primary source of reproductive isolation between these sympatric taxa.M.guttatus and M.nudatus differ in the pattern and timing of endosperm and embryo development. Some hybrid seeds exhibit early disruption of endosperm development and are completely inviable, while others develop relatively normally at first, but later exhibit impaired endosperm proliferation and low germination success. These developmental patterns are reflected in mature hybrid seeds, which are either small and flat (indicating little to no endosperm) or shriveled (indicating reduced endosperm volume). Hybrid seed inviability forms a potent reproductive barrier between M.guttatus and M.nudatus. We shed light on the extent of developmental variation between closely related species within the M.guttatus species complex, an important ecological model system, and provide a partial mechanism for the hybrid barrier between M.guttatus and M.nudatus.

• 出版日期2016-5