Secrets of Plant Pigments

29-33Colours of higher plant organs depend largely on the pigments they contain. These pigments are not only responsible for the beautiful colours we observe around us, they are also integral to the survival of the plants and life on earth too. THE world is like a colour box with waves of colours everywhere. The radiance of colour we see in and around our mundane life is bestowed on us mostly by the magnanimity of plants. The greenery of leaves and tender stems soothe our eyes. The withered yellow and red leaves fallen on the ground mark the onset of autumn. Come spring and the surroundings are bedecked with flowers of various shades. Colourful strawberries and apples are visually appealing. But pigments in plants do much more than just help plants perform aesthetic functions. We all know that photosynthesis is the first step in the food chain that connects all living organisms. Plants use chlorophyll to covert sunlight into energy they can store in simple sugar during photosynthesis. The concocted food is later utilized by plants to run different life processes. Pigments also play a significant role in pollination as well as propagation. A flower may be rendered conspicuous by the bright colour of its petals or perianth (floral parts not differentiated into sepals and petals) and thus attracts certain insects. However, majority of the compound-eye insects are bichromatic and they have just two types of colour pigment receptors. Their colour spectrum is limited and blue shifted compared to ours. Honeybees are trichromatic—they have three types of pigment receptors like us. They can distinguish a wider spectrum and that is why honeybees visit various coloured flowers to fetch honey and are mostly involved in pollination. Red colour is invisible to insects while they can see ultraviolet light and so insects distinguish flower colour different from humans.Some butterflies are also successful pollinators as they are able to distinguish flower colour like honeybees