448 / 2019-02-18 09:21:09

TOD1 Acts as a Conserved Pollen Tube Turgor Pressure Regulator in Angiosperms

Alkaline ceramidase, S1P, sexual reproduction, siphonogamy

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Sexual reproduction in angiosperms is siphonogamous, and the interaction between pollen tube and pistil is crucial for the successful fertilization. How can pollen tube regulate its turgor pressure is largely unknown. Our previous study (Chen et al., 2015, Nature communications) demonstrated that the mutation of Arabidopsis TurgOr regulation Defect 1 (TOD1), leads to the reduced male fertility, which is resulted from retarded in vivo pollen tube growth. TOD1 encodes a Golgi-localized alkaline ceramidase, a key enzyme for the production of sphingosine-1-phosphate (S1P), which is involved in turgor regulation in plant cells. Thus, turgor pressure plays pivotal roles in pollen tube growth in plant reproduction. TOD1 shows collinearity and synteny within many angiosperm species, from eudicots such as tomato (Solanum lycopersicum), basal eudicots such as lotus (Nelumbo nucifera), monocots such as rice (Oryza sativa), to basal angiosperms such as water lily (Nymphaea colorata). However, there is not collinearity with gymnosperm species, such as ginkgo (Ginkgo biloba). TOD1 from tomato, lotus, rice and water lily can partially rescue the Arabidopsis tod1 mutant phenotype. Furthermore, OsTOD1 is also specifically expressed in rice pollen grains and pollen tubes, which is similar to AtTOD1. Our data suggest that TOD1 acts conservatively in angiosperms, and this opens up an opportunity to dissect the role of sphingolipids in pollen tube turgor pressure control in angiosperms.