A protein that bosses plant cells around

Plant growth can seem like a busy construction site, with a lot of activity by components called microtubules, structures that capture, store and move around plant material to help grow and shape cells. Scientists have known about microtubules for half a century, but only now have they found what guides the direction of growth.

The construction site boss, researchers from the University of British Columbia say, is a protein called Clasp. The researchers report in the journal Nature Communications that the protein exists in strong concentrations around the sharp edges of newly formed plant cells. The protein overrides the difficulty microtubules would have in making their way around the edges to promote more plant growth.

In plants without Clasp, microtubules were not able to make their way around sharp cell edges, said Geoff Wasteneys, a botanist at the University of British Columbia and one of the study’s authors.In laboratory tests, Wasteneys and his colleagues found that these plants were severely stunted in growth.  “What really makes this intriguing in terms of evolution is that it provides us clues: In this case it’s about the evolutionary mechanisms that allow plants to become large.”

Helping out the family, even in good times
Acorn woodpeckers are industrious, cooperative birds that live in family groups. Each family has several “helper” woodpeckers that do not breed. These birds devote their time to gathering acorns and other food for the young. Researchers were surprised to find that helpers are more beneficial in the spring after a good crop than in one after a poor harvest.

“It makes a lot of intuitive sense that the helpers are a lot more useful when conditions are bad,” said Walter Koenig, an ornithologist at Cornell University. “But in fact it seems to be exactly the opposite.” After a good acorn crop, the average number of new offspring in a family group increased by about seven-tenths of an offspring per helper. In a bad year, helpers reduced the overall reproductive success.

That’s because when an acorn crop is bad, having a helper may not help, Koenig said. In fact, helpers might be eating up food that could otherwise go to fledglings. But in a good year, helpers are able to harvest extra food and contribute to the family’s food reserves. Helper woodpeckers are generally young adults actively looking for breeding opportunities.

Until they make a match, they help raise their younger siblings and other relatives. They seem willing to do this work because they are helping their genetic relatives, Koenig said. But as far as reproductive success goes, he added, “it’s not as good as being the parents.” These findings are in a recent issue of The American Naturalist.

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