Neópolis, Brazil
Neópolis, Brazil

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One of the major problems in tomato production is the frequent attack of pests. The use of wild tomato species made it possible to obtain pest resistant genotypes. Such resistance has been linked to the presence of allelochemicals called acylsugars, which are esters of fatty acids. The colorimetric method is normally used to quantify the levels of acylsugars, allowing an indirect selection of genotypes with high content of allelochemicals. This methodology has been used predominantly in the breeding programs of tomato to obtain pest-resistant genotypes. Despite the wide use of the colorimetric method for indirect selection of tomato genotypes with pest resistance, some steps of this methodology take great demand of time. Knowing the importance of the colorimetric method and, attempting to improve the efficiency and standardization of reading, we tried to evaluate new methodologies for quantifying the levels of acylsugars present in tomato leafets. Among the proposed methods, when using the spectrophotometer Multiskan FC with filter of 620 nm and doses of 100 μL per well (96 wells), we obtained results which were similar to the standard methodology. This methodological approach allowed for greater efficiency in the analysis, repeatability, greater standardization of results reducing the chance of errors during execution, besides the simultaneous analysis of many samples. Concluding, this method is feasible and effective and can be used to quantify acylsugars in tomato leafets with the purpose of indirect selection of resistant genotypes to pests.


Fracetto G.G.M.,University of Sao Paulo | Azevedo L.C.B.,UFU ICIAG | Fracetto F.J.C.,University of Sao Paulo | Andreote F.D.,University of Sao Paulo | And 2 more authors.
Scientia Agricola | Year: 2013

Considered as one of the most biodiverse biomes, the Amazon has a featured role in the discovery of new species of plants, animals and microorganisms, which may be important for the functionality of different ecosystems. However, studies on the impacts resulted from changes in the Amazon land use on microbial communities and their functions are still limited. In this context, the soil fungal diversity can act as an important indicator of environmental stress caused by land use of the Amazon. This study describes changes in soil fungal communities caused by different systems of land use (primary forest, secondary forest, agroforestry, agriculture and pasture). Communities were observed in each of the areas using denaturing gradient gel electrophoresis (DGGE) of 18S rRNA gene combined with the non-metric multidimensional scaling (NMDS). Unique bands indicated the dominance of particular fungal groups in each of the specific treatments, mainly in areas converted to pasture, which differed greatly from samples of other systems of land use (SLU). The analysis of partial sequence of the 18S rRNA gene of fungi in soils under primary forest, agriculture and pasture showed differences (p = 0.001), evidencing the fungal community response to such changes. Most abundant phyla were the Zygomycota in the soil under primary forest and agricultural land, and Basidiomycota in the soil under pasture. The results show that the Amazon soil is an ecosystem susceptible to environmental changes in regarding the fungi community inhabiting this niche.

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