Efeitos do óxido nítrico exógeno em plantas de milho submetidas a deficit hídrico

Abstract

Water stress is the environmental event that most impacts plant growth and development; in addition, it is suggested that the occurrences of climate change will increase drought situations in the main crops. Therefore, the development of mechanisms that minimize the consequences and or increase the tolerance of plants to drought are very important. In this perspective, it is possible to make use of the exogenous application of certain molecules, such as S-nitrosoglutathione (GSNO), a nitric oxide (NO) donor, which promotes a series of effects related to the response to low water availability in certain species. Research is being carried out in this direction, but there are still gaps to be filled. Thus, this study aimed to examine the effects of exogenous application of GSNO on gas exchange processes, chlorophyll content (SPAD index), and on enzymatic antioxidant and glutathione concentration in leaves and roots of Zea mays L. under drought. For this purpose, the maize cultivar BRS 1030, sensitive to water stress, was sown in 12 L pots. The treatments consisted of irrigation (keeping the plants at 70% of the field capacity of the soil

(CC)), and stress (kept at 50% of the CC), the latter being applied when the plants reached the V6 stage. For comparative terms, the tolerant hybrid DKB 390 was also subjected to these conditions, but not sprayed with the mentioned molecule. After 12 hours of the stress imposition, the plants were sprayed with S-nitrosoglutathione in concentrations of 50 and 100 μM every 2 days, staying 10 days of stress. At the end of this period, samples were collected. The results clearly pointed to an improvement in gas exchange parameters, with results similar to those presented by the control without stress, as well as glutathione contents, mainly in leaves, starch, soluble sugars and total reducing sugars, and in the APX and CAT activities in roots. These responses were dose-dependent, with better performance in the treatment where 50 µM of GSNO was used.