Abstract
In animal fertilization, numerous numbers of sperms are required for successful fertilization. In plants, however, it had long been thought that an ovule accepts only one pollen tube to complete fertilization even though huge amount of pollen is pollinated to stigmata. Recently, we reported a ‘fertilization recovery system’ in flowering plants that actively rescues failed fertilization of a defective mutant pollen tube by attracting a second, functional pollen tube. In typical flowering plants, two synergid cells beside the egg cell attract pollen tubes, one of which degenerates upon pollen tube discharge. We observed that fertilization was rescued when the second synergid cell accepted a wild-type pollen tube. Our results suggest that flowering plants precisely control the number of pollen tubes that arrive at each ovule and use a fertilization recovery mechanism to maximize the likelihood of successful seed set.
