Multiple factors contribute to outcrossing in a tropical emergent Dipterocarpus tempehes, including a new pollen-tube guidance mechanism for self-incompatibility

Tanaka Kenta, Kentaro K. Shimizu, Michiko Nakagawa, Kiyotaka Okada, Abang A. Hamid, Tohru Nakashizuka

    Research output: Contribution to journalArticle

    20 Citations (Scopus)

    Abstract

    The self-rejection system of Dipterocarpus tempehes (Dipterocarpaceae), an emergent tree of the lowland tropical forests of Borneo, were studied by means of pollination experiments, fluorescence microscopy of pollen tubes, and monitoring of ovary maturation patterns. Fruit set was higher in cross-pollinated flowers than in control and self-pollinated flowers, indicating the existence of pollen limitation and a self-rejection system. Although the adhesion and the germination of self-pollen and the growth of self-pollen tubes were not inhibited, the proportion of cross-pollen tubes that entered the style was 1.7-2.3 times higher than that of self-pollen tubes, indicating a partial self-incompatibility that inhibits self-pollen tubes from entering the style hollow. These results suggest, for the first time, that self-incompatibility is caused by a defect of pollen-tube guidance. We also suggest a threshold effect in number of pollen tubes or late-acting self-incompatibility to fully explain the drastic and uniform selection against self-pollinated flowers before ovary swelling. After that, maternal selection and/or inbreeding depression caused the abortion and delayed maturation of self-pollinated flowers. The advantages of the self-rejection process composed of partial early-acting self-incompatibility and relatively strong delayed abortion is discussed with respect to the general-flowering phenomenon in lowland dipterocarp forests.

    Original languageEnglish
    Pages (from-to)60-66
    Number of pages7
    JournalAmerican Journal of Botany
    Volume89
    Issue number1
    DOIs
    Publication statusPublished - 2002 Jan 1

    Keywords

    • Breeding system
    • Canopy access
    • Dipterocarpaceae
    • Inbreeding depression
    • Lambir Hills National Park
    • Pollen-tube guidance
    • Pollination experiment
    • Self-incompatibility

    ASJC Scopus subject areas

    • Ecology, Evolution, Behavior and Systematics
    • Genetics
    • Plant Science

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