Tropisms of Underground Shoots—Stolons and Rhizomes

Abstract

The review discusses current problems in research on growth-related plant movements (phototropism and gravitropism). The existing data on physiological and molecular mechanisms of tropisms in shoots and roots are presented. Special attention is paid to underground shoots (stolons and rhizomes), which grow transversely to gravity; this phenomenon is called diagravitropism. Phytochrome control is shown to play a role in the maintenance of horizontal growth of stolons and rhizomes, and the physiological mechanisms of the phototropism and diagravitropism are discussed. The switch from diatropic to orthotropic (vertical) growth of the apexes of underground shoots was shown to be dependent on the balance of carbohydrates and phytohormones. The prospects for further studies of the mechanisms of growth orientation and morphogenesis of underground diagravitropic shoots are outlined.