Aquaporinas: de canais de água a transportadores multifuncionais em plantas

Abstract

-(Aquaporins: from water channels to multifunctional transporters in plants). From the functional identification of the first plant aquaporin, in 1993, up to today, a lot of information about the structure, location and function of different members of this multigene family of membrane proteins was provided by the scientific community. Initially regarded as "simple water channels", the aquaporins have been shown to transport gases and small neutral solutes such as glycerol, urea and silicon, transforming the concept of transmembrane transport. Due to the redundancy of aquaporin genes and their distribution in all organs and plant tissues, these proteins have been considered essential in maintaining vital functions in plants such as water and nutrient uptake in roots, seed germination, photosynthesis, transpiration and reproduction. This work presents a review on molecular and functional characterization of aquaporins and their relevance for plant development and in response to environmental stresses. Despite advances in research on plant aquaporins, there are few studies with native species from tropical regions and therefore there is a vast field of research to be explored, given the differences in water availability, the occurrence of various environmental stresses in tropical biomes, and the mechanisms employed by plants of these regions to be adapted to the wide variety of environmental conditions. Key words -major intrinsic protein (MIP), solute transport, stress response, water balance RESUMO -(Aquaporinas: de canais de água a transportadores multifuncionais em plantas). Da identificação funcional da primeira aquaporina de plantas, em 1993, aos dias de hoje, uma grande quantidade de informações sobre a estrutura, a localização e a função dos diferentes membros desta família multigênica de proteínas de membrana foi disponibilizada pela comunidade científica. inicialmente consideradas como "simples canais de água", as aquaporinas se mostraram capazes de transportar gases e pequenos solutos neutros, como glicerol, uréia e silício, revolucionando o conceito de transporte transmembrana. Devido à redundância dos genes de aquaporinas e à sua distribuição em todos os órgãos e tecidos vegetais, essas proteínas têm sido consideradas essenciais na manutenção de funções vitais, como absorção de água e nutrientes em raízes, germinação de sementes, fotossíntese, transpiração e reprodução. O presente trabalho faz uma revisão sobre a caracterização funcional e molecular das aquaporinas e sua importância no desenvolvimento da planta e na resposta a estresses ambientais. Apesar dos avanços nas pesquisas com aquaporinas de plantas, existem poucos estudos com espécies nativas de regiões tropicais havendo, portanto, vasto campo de pesquisa a ser explorado, tendo em vista as diferenças na disponibilidade de água, a ocorrência de estresses ambientais diversos nos biomas tropicais e os mecanismos empregados pelas plantas dessas regiões para se adaptar à grande variedade de condições ambientais.Palavras-chave -balanço híd...

Seed imbibition and germination of Plathymenia reticulata Benth. (Fabaceae) affected by mercury: possible role of aquaporins

“…An evaluation of these results confirms that particularly in our study the drop in the germination of seeds treated with 10 -3 M HgCl 2 was caused by lower seed hydration and not by possible oxidative stress, as some authors suggest (Willigen et al 2006;Gaspar 2011).…”

“…Some authors have discussed the potentially toxic side effects of mercury on plant metabolism (Willigen et al 2006;Gaspar 2011) and, for this reason, it is important to study the possible oxidative stress caused by this metal. It can be done by quantifying the activity of the main reactive oxygen species scavengers, such as superoxide dismutase (SOD), catalase (CAT), and peroxidases (POX).…”

Precocity, yield and water-use efficiency of banana plants under planting densities and irrigation depths, in semiarid region

“…Aquaporins (water channel proteins) are involved with the membrane transport of gases, solutes and ions, and their genes are found in every plant organ and tissue. These proteins are essential for water and nutrient uptake by roots, photosynthesis, transpiration and adaptation to environment-related stresses (Gaspar, 2011). Xu et al (2014) identified a plasma membrane aquaporin gene in the banana plant that induces drought tolerance by reducing the membrane damage, improving the ionic distribution by maintaining the osmotic adjustment with a high cytosolic K + /Na + ratio, and downregulating genes responsive to ABA, thereby increasing the plant survival rate.…”

Manejo fisiológico com base em tratamento de sementes e aplicação de organominerais via foliar para sistemas de alto potencial produtivo de soja

“…A sua ação está na regulação do transporte de água durante a embebição, crescimento embrionário e protusão da radícula (GAO et al, 1999;GASPAR, 2011).…”