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.
hapless
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His is the kind of comment and question I hear every day from male managers in companies across the globe. It is typical of where many men are today in thinking about gender imbalances and power. Most women think they should be further ahead than they are. Martha Lane Fox turned on her hapless questioner, in front of an audience of smart, impatient young women, and with practiced precision, incinerated him for his backward framing. She won an easy round of applause--and an unnecessary enemy. He could have been turned; instead he was burned.
"The panel's approach in this case leads to the result that regulating the taking of a hapless toad that, for reasons of its own, lives its entire life in California constitutes regulating" interstate commerce, Roberts wrote.
Two great crises have converged on the British economy. Squeezed in the middle is the hapless figure of Rishi Sunak, the third prime minister since September, facing multiple questions about how long he will last.
Rivers threw two touchdown passes to Antonio Gates and rookie running back Branden Oliver's big day included his first two NFL touchdowns as the Chargers earned the league's first shutout this season in beating the hapless Jets 31-0 Sunday for their fourth straight win.
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