Photosynthesis and cell respiration modulated by water deficit in grapevine (Vitis vinifera L.) cv. Cabernet Sauvignon

Abstract

Winegrape productivity and quality has been related to the regulated deficit irrigation, with important implications for the plant bioenergetics. When water deficit is imposed to grapevine plants, alterations in overall photosynthesis and cell respiration are observed. The aim of this study was to assess the modulations promoted by water stress on photosynthesis and respiration in leaves of the cv. Cabernet Sauvignon (cv. CS) for better understanding the physiological responses related to its drought tolerance and quality improvement under water deficit. For this purpose, measurements of photosynthetic efficiency, leaf water potential, gas exchange and O 2 consumption were carried out. Leaf water potential, photosynthesis, stomatal conductance, transpiration and internal carbon concentration were significantly reduced upon stress, suggesting that plants of cv. CS present higher water use efficiency (A N /E) and lower carboxylative capacity (A N /Ci) under this condition. On the other hand, cell respiration increased more than 70 % as estimated by the increase of O 2 consumption measured 12 days after suspension of irrigation. Most of this effect was related to a four-fold increase of the mitochondrial alternative oxidase (AOX) activity. These data indicate a key role for the AOX pathway in the physiological responses of grapevines to water deficit, and it implies that analyses of the AOX activation patterns should be useful for programs aiming to improve the consistency of fruit production and quality of winegrape cultivars by regulated deficit irrigation.Keywords: Vitis vinifera, drought tolerance, irrigation management, respiratory chain regulation, plant bioenergetics.Modulações na fotossíntese e respiração celular relacionadas à deficiência hídrica eM Videira (Vitis Vinifera l.) cV. carbernet sauVignon resumo -A qualidade e produtivade das uvas viníferas têm sido relacionadas a privação regulada de irrigação, o que sugere implicações importantes para a bioenergética da planta. Quando submetidas ao déficit hídrico as videiras apresentam alterações globais na fotossíntese e na respiração. O objetivo deste trabalho foi avaliar as modulações promovidas pelo estresse hídrico na fotossíntese Braz. J. Plant Physiol., 21 (2) e respiração em folhas da cv. Cabernet Sauvignon (cv. CS) visando o melhor entendimento das respostas fisiológicas relacionadas com sua tolerância à seca e melhoria da qualidade sob estresse hídrico. Para tanto, mensurou-se a eficiência fotossintética, o potencial hídrico foliar, as trocas gasosas e o consumo de oxigênio. O potencial hídrico foliar, fotossíntese, condutância estomática, transpiração e concentração interna de carbono foram significativamente reduzidas com o estresse, sugerindo que as plantas da cv. CS apresentam alta eficiência no uso da água (A N /E) e baixa eficiência carboxilativa (A N /Ci) sob essa condição. Por outro lado, a respiração celular estimada pelo consumo de O 2 aumentou mais que 70 % aos doze dias após a suspensão da irrigação, sendo a maior parte desse ef...

Trocas gasosas e injúrias foliares visíveis em plantas jovens de Astronium graveolens Jacq. fumigadas com ozônio

“…fumigadas com O 3 (100 ppb/h, 4h/dia, sete dias). oxidativo em sistemas biológicos (Queiroz et al 2002, Martim et al 2009). O nível de peroxidação nas membranas dos tecidos foliares pode ser mensurado através do conteúdo de malondialdeído (MDA, um produto da lipoperoxidação) presente no material vegetal.…”

“…Ao final do experimento, plantas mantidas sob ar filtrado apresentaram menor teor de MDA do que aquelas submetidas ao estresse causado pelo ozônio. O mesmo ocorreu em plantas expostas ao excesso de metais pesados (Michael et al 2011) e ao estresse hídrico (Martim et al 2009 (Fernandes 2015) e não da morte celular, evidenciando a ativação de mecanismos endógenos de proteção.…”

Developing Crop-Specific Irrigation Management Strategies Considering Effects of Drought on Carbon Metabolism in Plants

“…Changes in plant growth elicited by low water availability have also been associated to modulations on the balance between photosynthesis and respiration. These processes are www.intechopen.com intimately related (Bartoli et al, 2005;Flexas et al, 2006;Martim et al 2009). In general, from the total carbon incorporated in carbohydrate by photosynthesis, more than 50% is spent in respiratory rates; nevertheless, this relationship may alter under drought conditions.…”

“…In this condition the water use efficiency (WUE) instantly defined as the ratio A N /E can be enhanced to maintain cellular metabolism and plant survival. This event can be mostly observed in plants drought tolerant like grapevine (Pou et al, 2008;Martim et al, 2009), alfafa (Erice et al, 2011) and droughttolerant maize (Hund et al, 2009). Mediterranean plants with different growth pattern showed increase in leaf WUE with the initial decrease of water availability, but WUE decreased with lower water availability (Medrano et al, 2009).…”

“…Changes in plant growth elicited by low water availability have also been related to modulations on the balance between photosynthesis and respiration. These processes are intimately related, and in the last decade has been increasing interest in the interaction between them (Bartoli et al, 2005;Flexas et al, 2006;Martim et al 2009). Photosynthesis is a complex process and to achieve optimal rates must occur the interaction of chloroplasts with cytosol and other organelles such a mitochondria.…”