Sulfur metabolism in sugarcane is affected by high titers of Leifsonia xyli subsp. xyli

Abstract

Abstract Aims Leifsonia xyli subsp. xyli (Lxx) is the most common sugarcane bacterial pathogen that affects plant development and primary metabolism. For example, cysteine and methionine are sulfur-containing essential amino acids used for bacterial growth and the title of Lxx in sugarcane plants might affect sulfur metabolism. The goal of this study were to evaluate how the increase in bacterial titers affects nutritional status and sulfur metabolism in sugarcane. Methods: The study was carried out with a susceptible sugarcane (Saccharum officinarum) genotype CB49260, with low and high Lxx titers, evaluating the mineral status and levels of primary metabolites. Results: Plants with high Lxx titers increased leaf sulfur content (S) compared to plants with low Lxx titers where plants with high Lxx titers displayed increased levels of sulfate, sucrose, maltose, raffinose, shikimic acid, malate, putrescine, glycerol, and, erythritol but decreased levels of methionine and glutathione in leaves. In the culm, plants with high Lxx titers displayed increased contents of maltose but decreased levels of threonine, ornithine, phenylalanine and myo-inositol when compared with plants with low Lxx titers. Conclusions: This study thus demonstrated that high bacterial titers increase sulfur demand in sugarcane. However, the increase in S content in the leaf did not result in higher sulfur assimilation, which was verified by increases sulfate level and decreases in methionine and glutathione levels. Therefore, our study showed that plant metabolism fails to meet the increased sulfur organic compound demand due to lower methionine and glutathione biosynthesis and methionine catabolism to putrescine biosynthesis in the leaves.