Gravitropism goes mainstream

How Do Plants Know Which Way Is Up And Which Way Is Down?:

Think of a seed buried in a pot (…) It’s dark down there in the potting soil. There’s no light, no sunshine. So how does it know which way is up and which way is down? It does know. Seeds routinely send shoots up toward the sky, and roots the other way. Darkness doesn’t confuse them. Somehow, they get it right…

As the resident expert on gravitropism, I had several friends send me this link, excited that they “knew all about this”. Krulwich takes this example from David Chamovitz’s new book, What a Plant Knows. He goes on to explain in words and drawings the concept of the starch-statolith theory of gravity sensing in plants. It’s an old concept that continues bearing fruitful research, as demonstrated by our recent work studying gravitropism in a starchless mutant.

The links between food, water, and climate change

By 2030, the gap between global water supply and demand is projected to be 40%, with much of the excess need due to agriculture. World population is projected to reach 10 billion by 2050, demanding greater yields in crop productivity than the current trends project. The water problem and the food problem are both occurring against the backdrop of global climate change, which exacerbates both problems and demands radical new approaches to solve these problems because of the need to cut greenhouse gas emissions.

This unholy trio of factors was highlighted in a talk by Sir John Beddington, UK Chief Scientific Adviser, at the UK Plant Sciences 2012 meeting, which he used as a point of departure for discussing the vital need for plant science research. If I had to boil down his talk into a concise summary, it would be that we need to produce more food with less greenhouse gas emission and less water on the same acreage within the next two decades. Of course none of this is news, but this talk brings all the pieces together in a single place nicely. In addition to pointing out the dangerous position humanity is in, Beddington suggests a few areas of plant science research that could address some of these issues. The rest of the conference was presumably concerned with a more detailed look at solutions, from what I can glean from the list of titles available. I’m embedding the video below and plan to write more about the areas of plant science involved in the future.

Flowering out of sync

image of pear flowers
All dressed up, but nobody's coming over. This pear's pollinators are not showing up.
As you may have noticed if you live around here, spring came really early this year. In fact, winter barely came at all, so spring has kind of been brewing since late February. But temps were in the 80’s several days this week, so spring seemed to arrive for real this week. Our silver maple began flowering a couple weeks ago, and this week our two Cleveland Select pears burst into flower. As I was walking past/under the trees, holding my breath to avoid the rank odor they emit, I noticed something unexpected. Actually, what I noticed was nothing: there was not the usual cloud of tiny flying things around the flower clusters. I’ve now spent ten or so minutes each day over the last three days observing the flowers, and I’ve counted a grand total of 3 insects.

Let me acknowledge that I am not an expert in pollinator interactions, not by a long shot. [Note: for a real treat on these kinds of natural history and phenology topics, you should read Rebecca in the Woods.] It could well be that I’m just there watching at the wrong time of day, or mis-remembering past years’ pollinators, but I don’t think so. I think what I’m observing is a plant flowering far earlier than usual due to above-average temperatures. Meanwhile, its usual pollinators aren’t yet active. I think we can probably add this to the list of unexpected results of global climate change. In our case, I’m excited at the prospect of this tree not producing fruits — they’re messy and kind of a pain. But imagine if this were a fruit tree, or a whole orchard of fruit trees with no pollinators. Yikes.

Finally some patent sanity

I’ve been casually following the litigation related to the patent mess surrounding BRCA1 and BRCA2 (see here and here for my previous comments). In short, those are two human genes linked to an increased likelihood of developing breast cancer. Their sequences were patented some years ago by the University of Utah, where they were identified, and exclusively licensed to a private company called Myriad Genetics.

Today, the US Supreme Court ruled on a separate but related case covering a patent for a medical diagnostic test. The Court found the patent invalid because it was not far removed from natural processes, which are not patentable. Experts in biotech patent law suspect that this ruling may set precedent that extends to the BRCA1 case. This would be a welcome development, and a sign of sanity in the fairly insane world that is the US patent system.

Memory of past insults

Memory of past insults:

In this sea of unknowns, there is at least one take-home message: epigenetic factors appear to be the vehicle by which plants transfer defense memories to offspring. Further evidence for this comes from the finding that the “grandchildren” of exposed plants inherit the defense memory, but the fourth generation does not. “The observation that inherited resistance reverts after three generations suggests the underlying mechanism is not a mutation or another stable genetic change,” says Georg Jander, a biologist at the Boyce Thompson Institute in Ithaca, NY who partnered with Rasmann.

Excellent video commentary on leaf modeling paper


I’m not sure how often the articles published in Science are accompanied by simple, clear video explanations, but I wish it were standard practice. The Coen/Bangham research groups applied high-resolution image analysis coupled with mathematical modeling to understand how leaves are formed. Their paper was just published in Science.

Kennedy Space Center in Transition

It’s hard to read about the state of the Kennedy Space Center these days:

At the apex of the space shuttle program, some 18,000 people worked here. Now, just 7,500 do. On a recent Wednesday morning, parking lots across the vast complex sat two-thirds empty.

I had the incredible good fortune to work at Kennedy in the run up to STS-95, on which we had a small experiment investigating gravity signaling in roots. During that period, the space center and the rest of the Cape were crawling with activity. I hope the next generation of space vehicles moves forward and reinvigorates KSC again soon.

32,000 year-old plants

New Life, From an Arctic Flower That Died 32,000 Years Ago

By taking advantage of a property of most plant cells, a Russian research group may have revived a 32,000 year-old plant:

They then took cells from the placenta, the organ in the fruit that produces the seeds. They thawed out the cells and grew them in culture dishes into whole plants.

As the article goes on to point out, if this can be confirmed this represents a unique opportunity to study recent evolution in this species. But just think about this for a second: these cells that were revived were in a squirrel hole for 32,000 years. Whoa.

Plant Defense uses the Clock

Plants Use Body Clocks to Prepare for Battle

Lest I gave the impression that the animal immune system was using the circadian clock but the plant defense system was not, we have this:

Some of the circadian-regulated genes are linked to wounding or healing responses, meaning that they can anticipate an attack from insects just as they anticipate the sunrise.

This is really cool work, showing that plants use circadian regulation of defense compounds to provide maximum protection at the most likely time of insect feeding.