Nutrients in vegetables vary according to the clock

You may not realize this, but most fruits and vegetables are still living when you eat them — this is what keeps them from turning mushy and limp. In a new study, researchers from Rice University have shown that these plants are not only living, but their metabolism continues to cycle in response to light/dark periods, influencing their nutritional quality:

“Vegetables and fruits don’t die the moment they are harvested,” said Rice biologist Janet Braam, the lead researcher on a new study this week in Current Biology. “They respond to their environment for days, and we found we could use light to coax them to make more cancer-fighting antioxidants at certain times of day.”

AJB Special Issue on Tropisms

I am honored to have a paper in this month’s American Journal of Botany, a special issue focused on plant tropisms. Below is a collection of links highlighting some of the work:

Scientists join forces to bring plant movement to light:

Elementary school students often learn that plants grow toward the light. This seems straightforward, but in reality, the genes and pathways that allow plants to grow and move in response to their environment are not fully understood. Leading plant scientists explore one of the most fundamental processes in plant biology—plant movement in response to light, water, and gravity—in a January Special Issue of the American Journal of Botany.

Low Phosphate Alters Lateral Root Setpoint Angle and Gravitropism (our paper):

Lateral root orientation and gravitropism are affected by Pi status and may provide an important additional parameter for describing root responses to low Pi. The data also support the conclusion that gravitropic setpoint angle reacts to nutrient status and is under dynamic regulation.

I’ll post again on the work that went into our paper, including a breakdown of the inputs of time and talent that made this work possible. In short though, three awesome students worked many hours in the lab over the course of four years to produce these insights.

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.

Why study plants?

A few years ago, I put together a talk to give to a science club here at OWU offering my answer to the question, “Why study plants?” I organized my ideas around the concepts of plants being beautiful, interesting, important, and useful. I still think these are useful categories to address the original question. But over the last several years, I have become increasingly convinced that the latter two reasons have grown in stature in my thinking at least, if not in actual stature with respect to the problems facing humanity.

My conviction on this point has crystallized recently as I read two separate, totally unrelated articles. I’ll discuss one of them today, and the other some other day.

In his annual letter on the activities of his foundation, Bill Gates articulates the need for more investment in crop research:

Over time, governments in both developed and developing countries focused less on agriculture. Agricultural aid fell from 17 percent of all aid from rich countries in 1987 to just 4 percent in 2006. In the past 10 years, the demand for food has gone up because of population growth and economic development—as people get richer, they tend to eat more meat, which indirectly raises demand for grain. Supply growth has not kept up, leading to higher prices.

He goes on to argue, among other things, that we place ourselves at risk by ignoring the need for agricultural improvement. Plants are sitting ducks for pathogens, and Gates points out the nasty wheat rust known as Ug99 as an example of the kind of threat posed to crops grown in monoculture. With this fungal pathogen, it is not a matter of if it will affect North American wheat production, just when.

In a place like the U.S., we’ve enjoyed the luxury of taking food for granted for so long, we can hardly imagine the impact that a crop failure would have on our economy. We assume that the yearly corn harvest, the crop that undergirds most of our food economy, will maintain low prices at the grocery — Gates points out that a mere 15% of our consumer spending goes toward food — and allow us to spend our paychecks on more scintillating purchases like iPads XBoxes (sorry Mr. Gates). Without sustained efforts to outrun pests and pathogens that attack crop plants, we are almost guaranteeing a major crop failure some day.

But there is another wrinkle to funding as it currently stands, and that is that by leaving half ($1.2 of $3.0 bil) of agricultural spending on the most important crops up to the private sector, we almost guarantee that crop improvements will be directed at wealthy, developed nations and pass over the poor, developing nations. Individuals and families will remain in poverty, scraping out subsistence yields with no surplus for the market, and no opportunity to join the global economy, largely because they lack the stability of predictable crop yields that only comes from research investment. In other words, this discussion quickly incorporates issues of social justice and the fight to end extreme poverty.

So this is one prong of an argument to invest in plant science research, either financially (if you are a billionaire) or with your time and talent. If you are interested in a career in research and have a desire to do good in the world, becoming a plant scientist is a path worth exploring. But this is not the only reason, there are several other great reasons to explore this field that I’ll talk about some other day.

Infinite possibilities

Interesting bit of research picked up by the mainstream press (albeit with no link to the article) in this week’s US News. In this case it’s a review article on the state of engineering plant secondary metabolism to create novel or high-value compounds:

Møller envisions a future where plants’ internal systems are re-engineered to create rare chemicals, such as artemisinin, a powerful anti-malarial drug that is found in trace amounts in only one plant worldwide. The plant would be rewired so that instead of making trace amounts of the drug, it would make lots of it.

Now that all the molecular tools are in place to even propose such an undertaking, the possibilities start to seem infinite.