Background C4 plants have been classified into three subtypes based on the enzymes used to decarboxylate C4 acids in the bundle sheath cells (NADP-ME, NAD-ME and PEPCK pathways). Evidences indicate that, depending on environmental factors, C4 plants may exhibit a certain degree of flexibility in the use of the decarboxylation mechanisms. In this context, the objective was to extend the knowledge on the degree of flexibility between the pathways of decarboxylation in sugarcane, a NADP-ME species, at different levels of water deficit. Results An experiment was carried out with two cultivars - RB92579 (tolerant to water deficit) and SP80–3280 (susceptible to water deficit) subjected to moderate level (− 1.5 to − 1.8 MPa), severe level (below − 2.0 MPa) and recovery (48 h after rehydration) and changes in the activities of the enzymes involved in the three C4 mechanisms and in gene expression were investigated. Our results showed that sugarcane uses the PEPCK pathway as a decarboxylation mechanism in addition to the NADP-ME, which was more evident under water deficit conditions for both cultivars. Conclusions The results obtained here, show that sugarcane increases the use of the PEPCK pathway as a decarboxylation mechanism, in addition to the NADP-ME pathway, under conditions of water deficit, particularly in the tolerant cultivar. Electronic supplementary material The online version of this article (10.1186/s12870-019-1745-7) contains supplementary material, which is available to authorized users.

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RESUMOO presente trabalho teve como objetivo avaliar o desenvolvimento do alface e controle de nematóides após serem introduzidas doses crescentes de Bacillus subtilis ao substrato, onde posteriormente a hortaliça foi transplantada em solo infestado com nematóides do gênero Meloidogyne. O experimento foi conduzido em estufa localizada na Unoeste -Presidente Prudente -SP. O substrato recebeu doses crescentes de Bacillus subtilis formulado em pó: 0,0%, 0,5%, 1,0%, 2,0% e 4,0% correspondentes a 0,0g, 5,0g, 10,0g, 20,0g e 40,0g. Foi utilizada a cultivar de alface Vanda. Avaliou-se comprimento de raiz e massa fresca da parte aérea de 20 mudas após 32 dias, sendo que 10 mudas foram transplantadas para o solo infestado com nematóides. O uso de Bacillus subtilis foi eficiente no controle do nematóide Meloidogyne spp. A dose de 4,0% aplicada ao substrato melhorou o desenvolvimento das plantas de alface. Palavras-chave: Rizobactérias. Meloidogyne. Lactuva sativa. Hortaliças. Substrato. CONTROL BIOLOGICAL OF NEMATODES IN LETTUCE WITH Bacillus subtilis ABSTRACTThis study aimed to evaluate the development of lettuce and control of nematodes after being introduced increasing doses of Bacillus subtilis the substrate where later the vegetable was transplanted into soil infested with nematodes of the genus Meloidogyne. The experiment was conducted in a greenhouse located in Unoeste -Presidente Prudente -SP. The substrate received increasing doses of Bacillus subtilis powder: 0.0% , 0.5 %, 1.0 %, 2.0 % and 4.0 % corresponding to 0,0g , 5.0g , 10.0g , 20,0g and 40,0g . It was used to grow lettuce Vanda. We evaluated the length of root and shoot fresh weight of 20 seedlings after 32 days, and 10 seedlings were transplanted into soil infested with nematodes. The use of Bacillus subtilis was efficient in the control of Meloidogyne spp. The dose of 4.0% applied to the substrate improved the development of lettuce plants.

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A alface (Lactuca sativa L.) é uma folhosa altamente consumida e apresenta vida pós-colheita curta, gerando assim muitas perdas e prejuízos. Na horticultura, o uso do silício tem demonstrado efeito benéfico da sua utilização em diversas plantas. Nesse sentido, o objetivo desse trabalho foi verificar a influência da aplicação foliar de doses crescentes de silicato de magnésio na produção e conservação pós-colheita da alface crespa. O silício por possuir relação direta na preservação contra danos oxidativos e na manutenção dos teores de clorofila, proporcionou um retardo à senescência e consequentemente uma melhor conservação pós-colheita da alface, prolongando por dois dias a sua vida útil na dose de 0,32 g/L. Porém, a aplicação de silicato de magnésio não promoveu o crescimento da alface crespa. Palavras-chave: Lactuca sativa L.. Horticultura. Perecibilidade. Nutriente. Silicato de magnésio. SILICON PROMOTES BETTER POST-HARVEST CONSERVATION OF LETTUCE ABSTRACT Lettuce (Lactuca sativa L.) is a heavily consumed hardwood and presents a short post-harvest life, thus generating many losses. In horticulture, the use of silicon has shown beneficial effect of its use in several plants. In this sense, the objective of this study was to verify the influence of foliar application of increasing doses of magnesium silicate on the production and post-harvest conservation of crisp lettuce. Due to its direct relationship in the preservation of oxidative damage and the maintenance of chlorophyll content, silicon provided a delay in senescence and a better postharvest conservation of the lettuce, extending its shelf life by 0.32 g/L. However, the application of magnesium silicate did not promote the growth of crisp lettuce.