Controle genético da resistência de Capsicum frutescens à Meloidogyne enterolobii
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Data
2016-10-27
Autores
Diniz, Guilherme Matos Martins [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Os nematoides das galhas estão entre os patógenos que mais causam prejuízos em cultivos protegidos de pimentão, destacando-se as espécies Meloidogyne incognita, M. javanica e M. enterolobii. Este último já foi relatado em plantas de Capsicum spp., e vem causando problemas, pois a utilização de genótipos resistentes a outras espécies não é eficaz em seu controle. Estudos relacionados à resistência a esse patógeno, bem como a obtenção de fontes de resistência ainda são escassos, o que dificulta a adoção de programas de melhoramento genético, visando a esse fim. Sendo assim, o presente trabalho teve por objetivo estudar a herança da resistência à M. enterolobii em Capsicum frutescens. O trabalho foi desenvolvido na UNESP-FCAV, Câmpus de Jaboticabal-SP. Para o estudo da herança da resistência, foi realizado o cruzamento entre C. frutescens, resistente a M. enterolobii e uma linhagem de pimenta C24, C. chinense, suscetível a nematoide. A partir desse cruzamento, foram obtidas as gerações F1, F2, RC1 e RC2. Depois de obtidas todas as gerações necessárias para o estudo, as plantas foram inoculadas com 5.000 ovos e juvenis de segundo estádio de M. enterolobii no ato do transplantio. Após 60 dias da inoculação, realizou-se a avaliação da resistência das plantas ao nematoide, coletando-se as raízes e realizando-se os procedimentos de extração dos nematoides em laboratório. A avaliação da resistência das plantas aos nematoides foi realizada com base no fator de reprodução (FR), sendo consideradas FR ≥ 1, suscetíveis, e FR < 1, resistentes. Os dados foram avaliados pelo teste qui-quadrado e cinco metodologias de avaliação dos genes envolvidos no controle, além do teste de máxima verossimilhança para a verificação da presença de efeitos relacionados ao ambiente ou polígenes. A análise genética mostrou ausência de dominância e epistasia, indicando ação gênica somente aditiva. A dominância apresentada tendeu à suscetibilidade, indicando que a resistência é recessiva. O número de locos segregantes mostrou que apenas um gene estaria envolvido na herança da resistência à M. enterolobii. O valor de herdabilidade foi alto, evidenciando possibilidade de ganho seletivo sendo um caráter pouco afetado pelo ambiente. Todas as plantas da geração F1 foram suscetíveis, as gerações F2 e retrocruzamentos tiveram variações de sintomas do parasitismo. A hipótese de herança monogênica foi aceita, de acordo com os métodos estatísticos utilizados no estudo, até o limite de significância do qui-quadrado. O controle genético da resistência à M. enterolobii, em C. frutescens é monogênico recessivo.
Root-knot nematode are among the pathogens that cause most damage in pepper crops protected highlighting the species Meloidogyne incognita, M. javanica and M. enterolobii. The latter has been reported in plants Capsicum spp., and causes problems since the use of resistant genotypes other species is not effective as a control. Studies related to resistance to this pathogen as well as obtaining sources of resistance are still scarce, hindering the adoption of breeding programs for this purpose. Therefore, this study aimed to study the inheritance of resistance to M. enterolobii in Capsicum frutescens. The study was conducted at UNESP-FCAV in Jaboticabal-SP. To study the inheritance of resistance was the cross between C. frutescens, resistant M. enterolobii and C24 pepper strain, C. chinense, susceptible to the nematode. From this junction were obtained F1, F2, BC1 and BC2. After obtaining all generations necessary for the study, the plants were inoculated with 5.000 eggs and juveniles of second stage M. enterolobii in transplanting the act. After 60 days of inoculation was performed to evaluate the resistance of plants to nematode collecting the roots and carrying out the nematode extraction procedures in the laboratory. The evaluation of plant resistance to nematodes was performed based on the reproduction factor (RF) is considered FR ≥ 1, and RF susceptible <1 resistant. The data were analyzed by chi-square test five methods of assessing the genes involved in the control beyond the maximum likelihood test for the presence of related environmental effects or polygenes. Genetic analysis showed no dominance and epistasis indicating only additive gene action. The dominance presented tended susceptibility, indicating that resistance is recessive. The number of loci segregating showed that only one gene was involved in the inheritance of resistance to M. enterolobii. The heritability value was high showing possibility of selective gain being one character unaffected by the environment. All plants of F1 generation were susceptible, generations, F2 and backcross had variations of symptoms of parasitism. The hypothesis of monogenic inheritance was accepted, according to the statistical methods used in the study, up to the limit of significance of the chi-square. The genetic control of resistance to M. enterolobii in C. frutescens is monogenic recessive.
Root-knot nematode are among the pathogens that cause most damage in pepper crops protected highlighting the species Meloidogyne incognita, M. javanica and M. enterolobii. The latter has been reported in plants Capsicum spp., and causes problems since the use of resistant genotypes other species is not effective as a control. Studies related to resistance to this pathogen as well as obtaining sources of resistance are still scarce, hindering the adoption of breeding programs for this purpose. Therefore, this study aimed to study the inheritance of resistance to M. enterolobii in Capsicum frutescens. The study was conducted at UNESP-FCAV in Jaboticabal-SP. To study the inheritance of resistance was the cross between C. frutescens, resistant M. enterolobii and C24 pepper strain, C. chinense, susceptible to the nematode. From this junction were obtained F1, F2, BC1 and BC2. After obtaining all generations necessary for the study, the plants were inoculated with 5.000 eggs and juveniles of second stage M. enterolobii in transplanting the act. After 60 days of inoculation was performed to evaluate the resistance of plants to nematode collecting the roots and carrying out the nematode extraction procedures in the laboratory. The evaluation of plant resistance to nematodes was performed based on the reproduction factor (RF) is considered FR ≥ 1, and RF susceptible <1 resistant. The data were analyzed by chi-square test five methods of assessing the genes involved in the control beyond the maximum likelihood test for the presence of related environmental effects or polygenes. Genetic analysis showed no dominance and epistasis indicating only additive gene action. The dominance presented tended susceptibility, indicating that resistance is recessive. The number of loci segregating showed that only one gene was involved in the inheritance of resistance to M. enterolobii. The heritability value was high showing possibility of selective gain being one character unaffected by the environment. All plants of F1 generation were susceptible, generations, F2 and backcross had variations of symptoms of parasitism. The hypothesis of monogenic inheritance was accepted, according to the statistical methods used in the study, up to the limit of significance of the chi-square. The genetic control of resistance to M. enterolobii in C. frutescens is monogenic recessive.
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Palavras-chave
Pimenta-malagueta, Herança, Nematoide das galhas, Chilli pepper, Inheritance, Root-knot nematode