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| Author(s): |
Noemi Carla Baron Cozentino
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Jaboticabal. 2019-06-11. |
| Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal |
| Defense date: | 2019-05-03 |
| Advisor: | Everlon Cid Rigobelo |
| Abstract | |
The representativeness of Brazilian agriculture is worldwide recognized, especially in the grains production such as soybean, maize and beans. Crops' yield, especially in the last decade, has presented significant growth, however, one of the negative aspects associated with this process is the concomitant increase in the use of pesticides and fertilizers. Currently, this issue has become a public health and environmental concern because of the toxicity and recalcitrance of these compounds. Among alternatives to the use of these inputs the study of microorganisms is promising because they constitute a great genetic patrimony, which houses metabolic pathways of great interest for several human activities, including agriculture. Microorganisms are able to interact in different ways with plants benefiting them and ensuring resources for themselves in return. They can act by improving nutrient supply, defense mechanisms and promoting growth under conditions of biotic and abiotic stress. Thus, the present study aimed the isolation of fungi from soil samples, focusing on the search for fungi of the genus Purpureocillium; their molecular characterization and the assessment of their in vitro plant growth promotion potential; and the selection of strains to be tested in planta in soybean, maize and bean. Fungal isolation was performed using conventional and selective media. The isolates had their DNA extracted and the ITS (Internal Transcribed Spacer) region of the ribosomal DNA and part of the coding region of the β-tubulin protein were sequenced. The plant growth promotion potential was assayed in vitro by measuring the phosphorus solubilization ability and the production of IAA (indoleacetic acid) and chitinases by the isolates. Greenhouse tests were performed with strains selected from in vitro screening, evaluating the effect of fungal inoculation on parameters such as plant height, dry mass, and phosphorus and nitrogen content in plants and soil. Among 211 isolates obtained, 30 were morphologically recognized as Purpureocillium. The molecular analysis allowed to identify them as representatives of the species Purpureocillium lilacinum (25 isolates), Purpureocillium lavendulum (4 isolates) and Metarhizium marquandii (1 isolate). From the results obtained for the phosphorus solubilization and the IAA and chitinases production by these 30 strains, seven were selected and tested with the three crops under greenhouse conditions. The strains were able to positively modify the evaluated parameters, including plant height, dry mass and phosphorus and nitrogen contents. Only a few studies evaluate the effect of the inoculation of these strains on plants and their direct effect on growth promotion, especially in aspects such as the increase of nitrogen levels. In addition, different strains stood out with each crop by changing different parameters, indicating the existence of specificity in the fungus-plant relationship. In-depth studies are needed, including a field assessment of their performance as well as aspects involving their interaction with each one of the crops. However, this study presents an innovative character which is the possibility of combining the pathogen control, commonly described for P. lilacinum against nematodes, to the action of growth promotion. In addition, P. lavendulum does not have any reports related to the subject in literature, as well as M. marquandii. (AU) | |
| FAPESP's process: | 15/17505-3 - Characterization of genes of Paecilomyces spp. of interest in plant growth promotion |
| Grantee: | Noemi Carla Baron Cozentino |
| Support Opportunities: | Scholarships in Brazil - Doctorate |