Matthew Jacobs

Blue leaves help plants get extra energy from sun

Nearly all life on Earth depends on the ability of plants to convert light into chemical energy. Chloroplasts, the little factories that carry out this conversion, are widely considered passive in this work: They just sit there and absorb whatever light hits them. But it turns out that’s not always the case. A team of researchers from the United Kingdom reports today in Nature Plants that it has discovered a species of shade-dwelling begonia called Begonia pavonina (above) that arranges light absorbing components in its leaves to boost their light absorption. Typical chloroplasts contain membrane-bound compartments called thylakoids that stack atop one another in a somewhat haphazard arrangement. In B. pavonina, however, this stacking is far more regular, creating what are known as photonic crystals. These crystalline arrays strongly reflect blue light, giving the leaves an iridescent glow. But more importantly, they concentrate the more abundant green and red wavelengths of light on the leaves’ energy absorbing apparatus. The upshot is that B. pavonina’s leaves soak up as much as 10% more energy than other low-lying forest dwellers. That may not seem like much, but under the thick canopies of Malaysian forests where B. pavonina lives, that extra energy gives the plant the juice it needs to edge out its competitors.