Banca de DEFESA: EDCLEYTON JOSÉ DE LIMA

Fungal Metabolisms as a Resistance Inducer and Biocontroller of Fungal Diseases of Forage palm

chitinase, beta-1,3-glucanase, biocontrol.

Forage palm (Opuntia ficus-indica Mill) is an important agricultural crop for the Brazilian Northeast, as its physiological and morphological characteristics are suitable for the region with a semi-arid climate. The stem of the forage palm is succulent, they have the CAM-type photosynthetic system and are xerophytic plants, these characteristics guarantee adaptation to environments with long periods of drought. As it is an important crop for small producers, it is essential that new studies are directed to enable sustainable measures to control pathogens and pests. As an alternative to the use of pesticides, biocontrol using microorganisms has proven to be highly viable and promising in controlling plant diseases. Despite being a rustic and resistant crop, its adaptive characteristics provide favorable conditions for the attack of phytopathogenic agents, mainly of fungal origin. Among the main pathogens that cause damage to crops are those that cause cladode and root rot, where the following fungi are classified: Fusarium solani, Scytalidium lignicolum and Lasiodiploidia theobromae. The aim of the work was to evaluate the production of fungal metabolites from endophytic fungi of Cactaceae in the biocontrol of phytopathogens that cause rot in cactus. The work was carried out at the Biotechnology Laboratory of the Research Support Laboratory Center (CENLAG) of the Federal University of Agreste de Pernambuco (UFAPE). Seven endophytic fungi from Cacteaceae were chosen, namely: Trichoderma harzianum (URM7210), Trichoderma aureoviride (URM6669), Trichoderma viride (URM6823), Trichoderma viride (URM6824), Syncephalastrum racemosum (URM6819), Penicillium glandicola (URM6268) and Triticharium dependos (URM6822). The phytopathogenic fungi Lasiodiplodia theobramae (URM4406), Scytalidium lignicolum (URM2313) and Fusarium solani (URM6264) were selected because they are the causal agents of rot in cactus pear. Antagonism was carried out using the confrontation method between the antagonist and the phytopathogen, consisting of placing 6 mm discs of both fungi on opposite sides of petri dishes, so that they could simultaneously reach the center of the dish. The evaluation was measured after seven (7 days). The production of the enzymes chitinase and beta-1,3-glucanase were carried out under submerged fermentation, for a period of 96 hours, under a controlled temperature of ±30ºC and 140 rpm, the quantifications of both enzymes were carried out according to established protocols. The antagonistic potential against L. theobromae, F. solani and S. lignicolum, showed that the genus Trichoderma is a promising antagonistic agent, as they obtained the highest percentages of inhibition, the effects that provide the antagonistic potential consist of the release of volatile compounds and non-volatile substances, competition for food and space, rapid mycelial growth and the production of lytic enzymes. The screening showed that T. viride (URM6823) was the largest producer of chitinase with 1,939 U/ml and for beta-1,3-glucanase, S. racemosum (URM6819) was chosen, which produced 5,795 U/ml. The factorial design showed that acidic pH, greater quantity of colloidal chitin and spores, were the characteristics that optimized the enzymatic production of chitinase, where a production of 2.277 U/ml was obtained. For beta-1,3-glucanase, the highest yeast and spore extract conditions and the lowest pH resulted in the production of 6.282 U/ml. It is concluded that endophytic fungi from Cactaceae have the potential to combat phytopathogenic fungi in cactus pear.

Forage palm (Opuntia ficus-indica Mill) is an important agricultural crop for the Brazilian Northeast, as its physiological and morphological characteristics are suitable for the region with a semi-arid climate. The stem of the forage palm is succulent, they have the CAM-type photosynthetic system and are xerophytic plants, these characteristics guarantee adaptation to environments with long periods of drought. As it is an important crop for small producers, it is essential that new studies are directed to enable sustainable measures to control pathogens and pests. As an alternative to the use of pesticides, biocontrol using microorganisms has proven to be highly viable and promising in controlling plant diseases. Despite being a rustic and resistant crop, its adaptive characteristics provide favorable conditions for the attack of phytopathogenic agents, mainly of fungal origin. Among the main pathogens that cause damage to crops are those that cause cladode and root rot, where the following fungi are classified: Fusarium solani, Scytalidium lignicolum and Lasiodiploidia theobromae. The aim of the work was to evaluate the production of fungal metabolites from endophytic fungi of Cactaceae in the biocontrol of phytopathogens that cause rot in cactus. The work was carried out at the Biotechnology Laboratory of the Research Support Laboratory Center (CENLAG) of the Federal University of Agreste de Pernambuco (UFAPE). Seven endophytic fungi from Cacteaceae were chosen, namely: Trichoderma harzianum (URM7210), Trichoderma aureoviride (URM6669), Trichoderma viride (URM6823), Trichoderma viride (URM6824), Syncephalastrum racemosum (URM6819), Penicillium glandicola (URM6268) and Triticharium dependos (URM6822). The phytopathogenic fungi Lasiodiplodia theobramae (URM4406), Scytalidium lignicolum (URM2313) and Fusarium solani (URM6264) were selected because they are the causal agents of rot in cactus pear. Antagonism was carried out using the confrontation method between the antagonist and the phytopathogen, consisting of placing 6 mm discs of both fungi on opposite sides of petri dishes, so that they could simultaneously reach the center of the dish. The evaluation was measured after seven (7 days). The production of the enzymes chitinase and beta-1,3-glucanase were carried out under submerged fermentation, for a period of 96 hours, under a controlled temperature of ±30ºC and 140 rpm, the quantifications of both enzymes were carried out according to established protocols. The antagonistic potential against L. theobromae, F. solani and S. lignicolum, showed that the genus Trichoderma is a promising antagonistic agent, as they obtained the highest percentages of inhibition, the effects that provide the antagonistic potential consist of the release of volatile compounds and non-volatile substances, competition for food and space, rapid mycelial growth and the production of lytic enzymes. The screening showed that T. viride (URM6823) was the largest producer of chitinase with 1,939 U/ml and for beta-1,3-glucanase, S. racemosum (URM6819) was chosen, which produced 5,795 U/ml. The factorial design showed that acidic pH, greater quantity of colloidal chitin and spores, were the characteristics that optimized the enzymatic production of chitinase, where a production of 2.277 U/ml was obtained. For beta-1,3-glucanase, the highest yeast and spore extract conditions and the lowest pH resulted in the production of 6.282 U/ml. It is concluded that endophytic fungi from Cactaceae have the potential to combat phytopathogenic fungi in cactus pear.