Auxin. When the banana is first exposed to sunlight after the leaf canopy dries, one face of the fruit is shaded. On exposure to sunlight, auxin in the banana migrates from the sunlight side to the shaded side. Since auxin is a powerful plant growth hormone, the increased concentration promotes cell division and causes the plant cells on the shaded side to grow. This asymmetrical distribution of auxin is responsible for the upward curvature of the banana. Gravity-sensing mechanisms Statoliths Plants possess the ability to sense gravity in several ways, one of which is through statoliths. Statoliths are dense amyloplasts, organelles that synthesize and store starch involved in the perception of gravity by the plant (gravitropism), that collect in specialized cells called statocytes. Statocytes are located in the starch parenchyma cells near vascular tissues in the shoots and in the columella in the caps of the roots. These specialized amyloplasts are denser than the cytoplasm and can sediment according to the gravity vector. The statoliths are enmeshed in a web of actin and it is thought that their sedimentation transmits the gravitropic signal by activating mechanosensitive channels. The gravitropic signal then leads to the reorientation of auxin efflux carriers and subsequent redistribution of auxin streams in the root cap and root as a whole. Auxin moves toward higher concentrations on the bottom side of the root and suppresses elongation. The asymmetric distribution of auxin leads to differential growth of the root tissues, causing the root to curve and follow the gravity stimuli. Statoliths are also found in the endodermic layer of the hypocotyl, stem, and inflorescence stock. The redistribution of auxin causes increased growth on the lower side of the shoot so that it orients in a direction opposite that of the gravity stimuli. Modulation by phytochrome Phytochromes are red and far-red photoreceptors that help induce changes in certain aspects of plant development. Apart being itself the tropic factor (phototropism), light may also suppress the gravitropic reaction. In seedlings, red and far-red light both inhibit negative gravitropism in seedling hypocotyls (the shoot area below the cotyledons) causing growth in random directions. However, the hypocotyls readily orient towards blue light. This process may be caused by phytochrome disrupting the formation of starch-filled endodermal amyloplasts and stimulating their conversion to other plastid types, such as chloroplasts or etiolaplasts. Compensation Bending mushroom stems follow some regularities that are not common in plants. After