Histologia, bioquímica e herança da resistência do genótipo de algodoeiro TX25 a Meloidogyne incognita, raça 3
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2014-01-31
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Universidade Federal de Goiás
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Meloidogyne incognita race 3 is a limiting factor for cotton crop, and the genetic resistance is one of the most desirable control measures for being environmentally and economically suitable. The objective of this research was to study the resistance inheritance of cotton genotype TX 25 to M. incognita race 3 and identify the resistance mechanism. Two experiments for phenotyping were conducted under greenhouse conditions, using two parental genotypes (susceptible FM 966 and resistant TX 25), backcross, generation F1 and generation F2. The plants were maintained for 120 days after inoculation (DAI). Plants were evaluated for gall index, egg mass index and reproduction factor. Histopathological study was conducted and the root systems evaluated at 2, 4, 7, 9, 11, 16, 18, 21 , 23, 29, 34 and 45 DAI. The roots werestained with acid fuscin to assess the nematode penetration. Rootlet cuts were made to observe the changes caused by the presence of the nematode in the root system of susceptible and resistant cotton cultivar. Biochemical tests were also conducted with the two parental genotypes. In this essay, the plants were kept in the greenhouse and inoculated with eggs and J2 of M. incognita. Assessments occurred at eight, 24 and 35 days after inoculation. The genotypes were compared biochemically as to total phenols, flavonoids, liquid chromatography and magnetic resonance imaging. The genotype TX 25 showed resistance to M. incognita race 3 when attacked by the nematode with the plants producing a hypersensitivity reaction. The crosses derived from TX 25 and FM 966 showed olygogenic resistance. TX 25 also shows glycosylated flavonoids and sugars that provide resistance to Meloidogyne incognita race 3.
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ALVES, Gleina Costa Silva. Histologia, bioquímica e herança da resistência do genótipo de algodoeiro TX25 a Meloidogyne incognita, raça 3. 2014. 84 f. Tese (Doutorado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2014.