Johnson Mark A, von Besser Kiera, Zhou Qing, Smith Evadne, Aux George, Patton David, Levin Joshua Z, Preuss Daphne
Howard Hughes Medical Institute, Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois 60637, USA.
Genetics. 2004 Oct;168(2):971-82. doi: 10.1534/genetics.104.029447.
In flowering plants, the egg develops within a haploid embryo sac (female gametophyte) that is encased within the pistil. The haploid pollen grain (male gametophyte) extends a pollen tube that carries two sperm cells within its cytoplasm to the embryo sac. This feat requires rapid, precisely guided, and highly polarized growth through, between, and on the surface of the cells of the stigma, style, and ovary. Pollen tube migration depends on a series of long-range signals from diploid female cells as well as a short-range attractant emitted by the embryo sac that guides the final stage of tube growth. We developed a genetic screen in Arabidopsis thaliana that tags mutant pollen with a cell-autonomous marker carried on an insertion element. We found 32 haploid-disrupting (hapless) mutations that define genes required for pollen grain development, pollen tube growth in the stigma and style, or pollen tube growth and guidance in the ovary. We also identified genomic DNA flanking the insertion element for eleven hap mutants and showed that hap1 disrupts AtMago, a gene whose ortholog is important for Drosophila cell polarity.
在开花植物中，卵细胞在包裹于雌蕊内的单倍体胚囊（雌配子体）中发育。单倍体花粉粒（雄配子体）伸出一根花粉管，该花粉管在其细胞质内携带两个精细胞抵达胚囊。这一过程需要通过柱头、花柱和子房的细胞，在细胞之间以及细胞表面进行快速、精确引导且高度极化的生长。花粉管迁移依赖于来自二倍体雌细胞的一系列长距离信号，以及胚囊发出的引导花粉管生长最后阶段的短距离吸引剂。我们在拟南芥中开展了一项遗传筛选，用插入元件携带的细胞自主标记对突变花粉进行标记。我们发现了32个单倍体破坏（hapless）突变，这些突变定义了花粉粒发育、花粉管在柱头和花柱中的生长，或花粉管在子房中生长和引导所需的基因。我们还确定了11个hap突变体插入元件两侧的基因组DNA，并表明hap1破坏了AtMago基因，该基因的直系同源基因对果蝇细胞极性很重要。
