The bacterium <i>Sinorhizobium meliloti</i>, transformed with the <i>lacZ</i> plasmid pXLGD4, was inoculated onto the roots of <i><a href="//commons.wikimedia.org/wiki/Medicago_truncatula" title="Medicago truncatula">Medicago truncatula</a></i> ecotype A17. At 7 days after infection, the plant roots were fixed, stained, and imaged by microscopy. On the left can be seen a curled root hair with an infection thread which penetrates all the way to the root cortex. On the right can be seen a growing root nodule primordium.
<a href="//commons.wikimedia.org/wiki/User:Ninjatacoshell" title="User:Ninjatacoshell">Ninjatacoshell</a>
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