Biological control of the bacterial wilt Ralstonia solanacearum by bioprotector with fungi chitosan from Cunninghamella elegans on tomatoes

Abstract

Fertilization is one of the most important means to improve plant production and nutrient uptake. Tomatoes plants are very exigent on fertilizers and sensitive to diseases. For satisfactory yield and fruit quality soil fertility and diseases need to be controlled. The aim of this paper was to evaluate the effectiveness of a bioprotector that contains fungi chitosan as an alternative biofertilizer, which releases nutrients and induces resistance against tomatoes wilt by Ralstonia solanacearum bacteria. The treatments were: 1-soluble NPK fertilizers (NPKF) in recommended rate (RR), 2-bioprotector (NPKP) with fungi chitosan in half of recommended rate (50% RR), 3-NPKP 100% RR, and 4-NPKP 150% RR. Treatments without bacterial inoculation (PO) and with bacterial inoculation (P1) were added to evaluate the plant characteristics (plant height, shoot diameter, number of leaves in ramification, fresh and dry matter of shoots). The symptom classes used to observe the induction of resistance were: (--) plants with no disease symptoms; (-) plant with slight symptoms; (+) plants with drastic symptoms and (++) plants died. Plants receiving the soluble fertilizers (NPKF) showed drastic disease symptoms one week after R. solanacearum inoculation, and all the plants died two weeks after inoculation. Plants with NPKP that contains Cunninghamella elegans in rates 50, 100 and 150% RR induced resistance for bacterial disease and promote better plant characteristics. The results showed that the bioprotector displays normal characteristics. The protector may be used as alternative for conventional fertilizers, especially inducing resistance for bacterial control.

Oligochitosan Synthesized by Cunninghamella elegans, a Fungus from Caatinga (The Brazilian Savanna) Is a Better Antioxidant than Animal Chitosan

“…Recent in vitro studies have shown that animal chitosan presence increased the formation of oxalate crystals by approximately 15 times and altered the ratio between CaOx dihydrate (COD) and monohydrate (COM) crystals by 1:4 to 1:2. In addition, the presence of chitosan reduced the size of the COM crystals by approximately 50% and altered the crystal surface charge, making them smaller and less negative and, therefore, more susceptible to adhering to the surface of renal epithelial cells [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ].…”

“…This species can metabolize many compounds through demethylation and oxidation [ 25 ]. Moreover, several studies have demonstrated that this species synthesizes chitosan in good quantities, compared with other fungi [ 26 , 27 , 28 ].…”