title: A novel pollen-pistil interaction conferring high-temperature tolerance during reproduction via CLE45 signaling.
abstract: Flowering plants in the reproductive stage are particularly vulnerable to ambient temperature fluctuations. Nevertheless, they maintain seed production under certain levels of exposure to temperature change. The mechanisms underlying this temperature tolerance are largely unknown. Using an in vitro Arabidopsis pollen tube culture, we found that a synthetic CLV3/ESR-related peptide, CLE45, prolonged pollen tube growth. A subsequent screen of Arabidopsis mutants of leucine-rich repeat receptor-like kinase genes identified two candidate receptors for CLE45 peptide, STERILITY-REGULATING KINASE MEMBER1 (SKM1) and SKM2. The double loss-of-function mutant was insensitive to CLE45 peptide in terms of pollen tube growth in vitro. The SKM1 protein actually interacted with CLE45 peptide. CLE45 was preferentially expressed in the stigma in the pistil at 22°C, but upon temperature shift to 30°C, its expression expanded to the transmitting tract, along which pollen tubes elongated. In contrast, both SKM1 and SKM2 were expressed in pollen. Disturbance of CLE45-SKM1/SKM2 signaling transduction by either RNAi suppression of CLE45 expression or introduction of a kinase-dead version of SKM1 into skm1 plants reduced seed production at 30°C, but not at 22°C. Taken together with the finding that CLE45 peptide application alleviated mitochondrial decay during the in vitro pollen tube culture, these results strongly suggest that the pollen-pistil interaction via the CLE45-SKM1/SKM2 signaling pathway sustains pollen performance under higher temperatures, leading to successful seed production.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan. Electronic address: satoshi@biol.s.u-tokyo.ac.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Endo
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Shinohara
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Matsubayashi
authors.forename: Hiroo
authors.initials: H
authors.lastname: Fukuda
mesh_terms: D000222:Adaptation, Physiological; D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D035264:Flowers / Q000502:physiology*; D006358:Hot Temperature; D008565:Membrane Proteins / Q000378:metabolism*; D011058:Pollen; D053205:Pollen Tube / Q000254:growth & development / Q000502:physiology; D012098:Reproduction; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; C581881:CLE45 protein, Arabidopsis; D008565:Membrane Proteins