A revolução verde e a biologia molecular The green revolution and the molecular biology

Abstract

At the turn of this century, the genes responsible for the height reduction of the wheat and rice varieties that made possible the socalled Green Revolution of the 1960s were identified. More recently, it has been shown that this change in plant architecture results from a lack of gibberellin effects, the hormones that cause the internode elongation of stems, but whereas in wheat the reduction in size was accounted for by a gain of function mutation that interfere with the signalling pathway of the gibberellins, in the rice resulted from a loss of function mutation that prevents the synthesis of those hormones. Although gibberellins are the major hormones responsible for stem elongation, it is discussed a maize mutant in which the height reduction is caused by a decrease in auxin availability. These and other discoveries in molecular biology provide the new revolution required in agriculture with new tools in order to fulfil the global demand for increased food production, under the pressure of a continuous expansion of crops for energy production. Key-words: Auxins, gibberellins, Green Revolution, semi-dwarfing genes, transgenics. * Secção de Biologia Vegetal, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa, Quinta da Torre, 2829-516 Caparica. E-mail: ffh@fct.unl.pt Recepção/Reception: 2009.07.08 Aceitação/Acception: 2009.08.13 Homenagem a Norman Ernest Borlaug, Prémio Nobel da Paz, mentor e impulsionador da chamada “Revolução Verde”, no seu nonagésimo quinto aniversário. Norman Borlaug faleceu no passado dia 12 de Setembro, após doença prolongada. Será recordado pelos seus familiares e pelos amigos que com ele conviveram, mas também por milhões de pessoas, homens e mulheres, em todo o mundo, pelo seu contributo decisivo para minorar os problemas da fome e da miséria nos países menos desenvolvidos, particularmente na Ásia. Até sempre, Norman. REVISTA DE CIÊNCIAS AGRÁRIAS 246