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DIFFERENTIAL POLLEN‐TUBE GROWTH RATES AND NONRANDOM FERTILIZATION IN HIBISCUS MOSCHEUTOS (MALVACEAE)
Author(s) -
Snow Allison A.,
Spira Timothy P.
Publication year - 1991
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1991.tb12608.x
Subject(s) - pollen tube , biology , pollen , outcrossing , botany , callose , human fertilization , malvaceae , outbreeding depression , hibiscus , selfing , pollination , horticulture , agronomy , inbreeding , population , demography , cell wall , sociology
The prevalence of nonrandom fertilization due to postpollination events has rarely been studied in natural populations, despite important implications for outcrossing rates, mate choice, and plant fitness. Nonrandom paternity within fruits can be caused by both unequal fertilization and unequal embryo abortion. Using self‐compatible Hibiscus moscheutos , we studied the potential for nonrandom fertilization by comparing growth rates of pollen‐tubes from different donors. The branched style of Hibiscus allowed within‐flower comparisons between pollen donors. Relative pollen‐tube growth rates were determined by applying pollen from pairs of donors to different stigmas on adjacent stylar branches. We then measured the number of callose plugs per tube in cross‐sectional transects across the style after 3 hr. We demonstrate that rates of callose plug formation can be used as a sensitive indicator of relative pollen‐tube growth rate. Differences between pollen donors were common and repeatable. Self‐pollen‐tubes grew slower than outcross pollen‐tubes in some crosses and faster in others. Allozyme variation in glucose phosphate isomerase was used to show that individuals with fast‐growing pollen‐tubes sired a disproportionate number of seeds following mixed pollinations (up to 72%). Since seed abortion was negligible, we conclude that variation in pollen‐tube growth rates leads to nonrandom paternity within fruits.