Ray S M, Park S S, Ray A
Department of Biology, University of Rochester, NY 14627, USA.
Development. 1997 Jun;124(12):2489-98. doi: 10.1242/dev.124.12.2489.
In flowering plants, pollen grains germinate on the pistil and send pollen tubes down the transmitting tract toward ovules. Previous genetic studies suggested that the ovule is responsible for long-range pollen tube guidance during the last phase of a pollen tube's journey to the female gametes. It was not possible, however, to unambiguously identify the signaling cells within an ovule: the haploid female gametophyte or the diploid sporophytic cells. In an effort to distinguish genetically between these two possibilities, we have used a reciprocal chromosomal translocation to generate flowers wherein approximately half the ovules do not contain a functional female gametophyte but all ovules contain genotypically normal sporophytic cells. In these flowers, pollen tubes are guided to the normal but not to the abnormal female gametophytes. These results strongly suggest that the female gametophyte is responsible for pollen tube guidance, but leave open the possibility that the gametophyte may accomplish this indirectly through its influence on some sporophytic cells.
在开花植物中，花粉粒在雌蕊上萌发，并沿着花粉管通道向下向胚珠生长。先前的遗传学研究表明，在花粉管向雌配子生长的最后阶段，胚珠负责远距离引导花粉管。然而，无法明确鉴定胚珠内的信号传导细胞：单倍体雌配子体还是二倍体孢子体细胞。为了从遗传学上区分这两种可能性，我们利用相互染色体易位来产生花朵，其中大约一半的胚珠不包含功能性雌配子体，但所有胚珠都含有基因型正常的孢子体细胞。在这些花朵中，花粉管被引导至正常的雌配子体，而不是异常的雌配子体。这些结果强烈表明，雌配子体负责花粉管引导，但也留下了一种可能性，即配子体可能通过对某些孢子体细胞的影响间接完成这一过程。
