COSTALES MENENDEZ, Daimy; ANN GORDON, Trudy    FALCON RODRIGUEZ, Alejandro B. Variations in the response of defensive markers and in the contents of primary metabolism components in tobacco (Nicotiana tabacum, L.) seedlings applied with chitosan. []. , 35, 2, pp. 98-104. ISSN 0258-5936.

Twenty five days old tobacco plants (Criollo 98) were treated with different concentrations (0, 0,1, 0,5, 1, 2,5 g.L^-1) of a chitosan polymer by soil drench to the rhizosphere. At 30 days soluble protein and reducing sugar contents were determined in plant leaves, as well as, defense enzymatic markers (Phenylalanine ammonia liase (PAL), EC 4.3.1.5 and ß 1-3 glucanase, EC 3.2.1.6). In addition, enzymatic activity of nitrate reductase (EC 1.6.6.1) was detected at 30, 37 and 44 days after planting. Treatments with chitosan polymer did not cause significant changes in soluble protein contents in tobacco leaves, excepted for the lowest concentration tested, while all chitosan treatments affected the reducing sugar contents, by decreasing it, mainly with the two intermediated concentrations. These two treatments also caused significant reductions of nitrate reductase enzymatic activity, regarding to control activity, at 30 and 37 days after planting. In turn, defensive markers evaluated were induced above control, depending on concentration tested. PAL activity was increased above control with the lowest and the highest chitosan concentration employed (0.1 y 10 g.L^-1), while ß 1-3 glucanase was significant activated with all chitosan treatments tested, causing 2,5 g.L^-1 the maximum activity found. All results showed that defense induced in tobacco plants by chitosan, affected compound contents and enzymatic activity related to the primary metabolism and this influence depends on the concentration of the polymer tested, as well as the marker evaluated.

: tobacco; chitosan,; proteins; carbohydrates; enzymatic responses.

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