четверг, 8 сентября 2016 г.

This blue-leafed plant isn't afraid of the dark

This blue-leafed plant isn't afraid of the dark
This blue-leafed plant isn't afraid of the dark

peacock begonia blue leaf
The peacock begonia gets its iridescent blue color from tiny photonic crystals. (Photo: Matthew Jacobs/University of Bristol)

Fruits and flowers come in a wide range of colors, which can help plants attract beneficial animals like pollinators. The leaves are usually green, though, since that's the color of chlorophyll, the pigment plants use for photosynthesis.

But photosynthesizers don't necessarily have to be green. Many plants have reddish foliage, for example, due to the presence of other pigments in addition to chlorophyll, like carotenoids or anthocyanins. And before Earth had an oxygen atmosphere, the planet may have even gone through a "purple phase," led by violet-hued microbes that used a different light-sensitive molecule — retinal — instead of chlorophyll.

And now, thanks to a team of photonics researchers and biologists, we're learning about another odd twist on photosynthesis: bright blue begonias.

Tangled up in blue

begonia with blue leaves

Unlike the purple microbes, these begonias' blue leaves rely on chlorophyll just as green vegetation does. Yet unlike many red-leafed plants, they don't get their color from additional pigments, either. According to a new study published in the journal Nature Plants, their sapphire foliage comes from something even more bizarre: nanoscale crystals that help them survive in the darkness of a rain-forest understory.

Begonias are popular houseplants, partly because they can survive indoors without direct sunlight. That skill evolved among wild begonias on tropical and subtropical forest floors, where only slivers of sunlight trickle through the canopy above. For photosynthesis to work there, chloroplasts — the cell structures that contain chlorophyll — have to make the most out of what little light they get.

More than 1,500 begonia species are known to science, including a few that have long dazzled humans with a bluish sheen to their leaves. As the new study explains, however, the biological purpose of these blue leaves has been unclear, leading scientists to wonder if it deters predators or protects plants from too much light.

That mystery persisted until researchers from the U.K.'s University of Bristol and University of Essex noticed something about the peacock begonia (Begonia pavonina), a species native to montane forests in Malaysia. It's known for bright green leaves that sometimes, at certain light angles, glint iridescent blue. Yet it stays green when grown in bright light, they found, turning blue only in relative darkness.

The dark crystal

blue morpho butterfly in Costa Rica
The blue morpho butterfly owes its iridescent wings to photonic crystals. (Photo: caspar s/Flickr)

Normally, chloroplasts contain flattened, membrane-bound sacs known as thylakoids, which are loosely organized into stacks. These stacks are where photosynthesis happens, both in green plants and in blue begonias. In the latter, however, thylakoids are arranged more precisely — so precisely, in fact, they form photonic crystals, a kind of nanostructure that affects the motion of photons.

"[U]nder the microscope, individual chloroplasts in these leaves reflected blue light brightly, almost like a mirror," says lead author Matthew Jacobs, a Ph.D. biology student at the University of Bristol, in a statement about the discovery.

"Looking in more detail by using a technique known as electron microscopy, we found a striking difference between the 'blue' chloroplasts found in the begonias, also known as 'iridoplasts' due to their brilliant blue iridescent coloration, and those found in other plants. The inner structure had arranged itself into extremely uniform layers just a few 100 nanometers in thickness, or a 1,000th the width of human hair."

Those layers are small enough to interfere with blue light waves, and since the begonia leaves are blue, Jacobs and his fellow biologists knew there must be a connection. So they teamed up with photonics researchers at the University of Bristol, who realized the natural structures look like man-made photonic crystals used in tiny lasers and other devices that control the flow of light.

With the same techniques used to measure those artificial crystals, the researchers began shedding light on the peacock begonia's version. Its iridoplasts reflect all blue light, making them appear blue without pigment, similar to iridescent blue animals like the blue morpho butterfly. They also absorb more green light than standard chloroplasts, the study found, offering a clue about why begonias turn blue.

Guiding light

forest canopy in Malaysia
Dense rain-forest canopies force shorter plants to make the most of meager sunlight. (Photo: THPStock/Shutterstock)

Green plants look green because they mainly absorb other wavelengths of light, leaving green to be reflected to our eyes — and down through gaps in the canopy. So while a ceiling of trees hogs lots of blue light, green is less scarce on forest floors. And since iridoplasts concentrate green light, they may help begonias live in deep shade by using available light more efficiently. When the researchers measured photosynthesis rates in dim conditions, they found blue begonias were harvesting 5 to 10 percent more energy than normal chloroplasts in green plants.

That isn't a huge difference, but in hardscrabble rain forests, it might give begonias the boost they need. And learning more about their foliage might benefit humanity, too, the Bristol news release adds, providing blueprints we could use "in other plants to improve crop yields, or in artificial devices to make better electronics."

More research will be needed to investigate potential perks like those, the study's authors say, and to reveal how rare this phenomenon really is. The study found that peacock begonias contain a mix of iridoplasts and normal chloroplasts, suggesting the blue structures "function almost like a backup generator," co-author and Bristol biologist Heather Whitney tells Popular Mechanics. Plants may use traditional chloroplasts if there's enough light, then switch when light levels drop too low.

"It's just wonderful and logical to think that a plant has evolved an ability to physically manipulate the lighting around it in a variety of different ways," she says.

Even if this is widespread, it highlights an important point about people and plants. The plant kingdom is full of amazing adaptations that can help humans, from life-saving medications to light-bending crystals, but they tend to grow in forests — ecosystems that face mounting pressure globally from logging and agriculture.

Blue begonias may be safe, but they're just a hint of the treasures hidden in what's left of Earth's old-growth forests. As Whitney tells the Washington Post, living in a competitive ecosystem pushes plants to evolve or perish. "They've probably got loads of tricks we don't know about yet," she says, "because that's how they survive."

(Peacock begonia photos courtesy of Matthew Jacobs/University of Bristol)

In a couple of months, I will turn 40 years old. When I was a kid, that was the age that seemed impossibly old. The age after which we weren't supposed to trust people, the age that was "grown up" — to my mind, at least.

Of course, now that I've almost reached that age, I realize that's not the case. So, what have I learned? My first golden rule is this:

1. Plan for the future you want, not the one other people tell you to have.

I wasted a lot of time when I was younger trying to fit into other people's ideas of my future instead of planning for the future I wanted.

Here's a practical example of how that plays out. The typical advice is that you should start saving for retirement in your early 20s, or by your 30s at the very latest. I did that, diligently saving up, starting with my first job because I was told to.

Now, that can be great advice and it's smart to follow it — but only if you see yourself wanting a straightforward retirement. Do you want to work hard, full-time for 40ish years and then quit altogether? If so, save away (and start ASAP).

But I made a different choice, for two reasons:

1. All the jobs that would have allowed me to save for retirement and retire at 65 meant I would have had to sacrifice the life I wanted to lead.

2. I don't ever really want to not work. I want to keep writing, editing, teaching and doing small, interesting jobs on the side until I die. Taking jobs that I don't want so that I can retire and do what I "really" want doesn't make sense for me/ I'm already doing what I really want to do.

So, plan for your financial future — but take into account that your future may not look like your friends' or your parents' older years. This applies to things other than finances, too. Do you want children? Do you want to get married and have a big wedding and honeymoon? If not, your 30s and 40s will look different than the traditional path. If you do want those things, start preparing for both of those eventualities now; babysit for friends' and neighbors' kids so you can learn about how to care for kids; prioritize finding a mate so you can have time to prepare as a couple for kids.

Personally, I chose to neither marry nor have children because I have other priorities. Remember, there's more than one way to live an adult life. Choose what's best for you, and prepare for it.

2. Take care of your body

Learning how to cook healthy meals isn't just about a healthier you; it's another way to spend time with friends. (Photo: Monkey Business Images/Shutterstock)

Regardless of any other life choices, you want to be as healthy as you can be now and into your future. By your 30s, you should have put smoking cigarettes behind you, and have figured out a workout plan that you can stick to. You should be able to cook or prepare meals for yourself that are healthy and satisfying. Your health care should work for you and involve some preventative care — you're too old to be seeing a health professional only when you get ill or hurt yourself.

3. Know what brings you joy

What do you love to do? What makes you happy is a key facet of adult life — not so you can indulge in it all the time, but so you have a toolbox that you can reach into when you need to. Look past the superficial answers here (cocktails, a great TV show) and dig in. What brings you deep-down joy? If you haven't discovered this by the time you're halfway through your life, you are missing out. Which leads me to:

4. Know how to pull yourself out of a rut

Awful things will happen in your life. It's true for everyone, and I'm sorry to tell you that. A rip-your-heart-out breakup, the loss of a family member, a dismissal from a job, a car crash, or even a series of low-level frustrations will bring you down at some point. What can you do to pull yourself out of that negative place? What are the things you can do to care for yourself? Who can you lean on in hard times? This is a life skill that few of us want to think about but one that's invaluable when you need it. By the time you turn 40, you should have some ideas about how to recover from setbacks and grief.

5. Be able to say 'no'

Being an adult means that sometimes you need to put yourself and your work ahead of other people's needs. The best way to know when and how to say no is to practice it. (And yes, it does get easier over time.)

6. Take non-work time for what you care about

At this point in your life, you should have expanded the ways you spend your time beyond work. If you love nature, then find a way to make it a part of your week, every week. (Photo: Sjale/Shutterstock)

By the time you hit 40, you should know what you love outside your work life, and be doing it (even if you adore your job). Whether that's spending time with your family, traveling, volunteering with an organization whose ideals you support or learning new skills in your favorite hobby, a well-rounded person doesn't just work.

7. Know your boundaries and enforce them rigorously

This is honestly one of my favorite things about being an adult. You are now empowered by age and experience. You don't have to take anyone's abuse or cruelty; if friends or family members aren't treating you with love and respect, speak with them about it. If they don't stop their behavior after you've made clear that it hurts you, walk away from those relationships. There's no room for toxic relationships once you're an adult, and boundaries are for you to set and enforce. It's OK for some people to disagree with those boundaries — they can make their own.

8. Show up for the people you love

It's easy to be flaky when you're young, and most are forgiven for it. But once you're through your 30s, it's time to stop ditching friends because you're too busy or ghosting from a party. Be there for the people you love when they need your help, your company or a shoulder to cry on. Thank your hosts when you leave their party with a handshake or a hug. Send thank-you notes (email is fine); send flowers (or plants, or chocolate); RSVP; and show up if you have RSVP'd, even if you aren't feeling yourself that night. Taking care of yourself doesn't mean you get to disregard other people or treat them shabbily.

9. Make time for yourself — and be specific about what that is.

No, I'm not talking about spa days. Sure, those are nice, but why is that the only thing people think of when they think of taking personal time? Whatever it is you need to do for yourself, do it on the regular. As 60-year-old reader Nancy told writer Mark Manson, "... do something for yourself every day, something different once a month and something spectacular every year.” That's a solid goal.

10. Accept that even the best-laid plans won't work out

You don't have control over everything, and by the time you're 40 you will have realized that — or made yourself crazy in the process!

Original article and pictures take http://www.mnn.com/earth-matters/wilderness-resources/blogs/blue-leaves-peacock-begonia site

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