Alterações metabólicas associadas ao crescimento de plântulas de dois genótipos de Sorgo sob salinidade

Abstract

Sorghum (Sorghum bicolor L.) is one of the most widely cultivated cereals in the world, being used worldwide for animal feed and in some countries even for human food. Salinity is one of the abiotic stresses that most impact the world cereal production. It causes many undesirable physiological, morphological, and biochemical alterations. Thus, understanding the impact of this stress on crops is of utmost importance for global food production. In this sense, seedlings with 3 days of germination of two sorghum genotypes (CSF18 and CSF20) were submitted to salinity (0 and 75 mM NaCl) to analyze the morphological and metabolic changes associated with the initial development of seedlings when exposed to these conditions. For this, two experiments were conducted with the two cultivars individually. Each experiment was conducted in an entirely randomized design in a 2 x 5 factorial scheme composed of two salinity levels, within the times of 0, 24, 48, 72, and 96 hours after treatments were applied, totaling 7 days of age. After each treatment period, analyses of growth parameters, inorganic solutes, and metabolic profiles of the two genotypes were performed. As a result, salinity promoted a length reduction in CSF18 only in the aerial part after 72 h of stress, while in CSF20 the growth reduction occurred after 24 and 48 h in the aerial part and roots, respectively, in both genotypes evaluated. This behavior can be observed through the sPLS-DA of the metabolic profiles in the aerial parts, of both genotypes. In CSF20, the profiles are more distant in relation to the times, while in CSF18 at 24h, the metabolic profiles of the saline treatment and control, are very close. It was also possible to notice changes in the metabolite profiles of both genotypes, when exposed to salt treatment, over time. Related to component 1, important carbohydrates such as sorbose and fructose showed high relative values for both genotypes during the initial stress period and decreased with time because they are an energy source for growth. Component 2 separated the control and salt treatments after 24 h with an influence of amino acids and organic acids that showed low abundance in CS18 and high abundance in CSF20. Thus, the results obtained, contribute to the understanding of the metabolic variations associated with the response to salinity throughout the time of seedling establishment, and may contribute in the future to the development of new varieties of sorghum tolerant to salt stress.