Anatomia e morfologia de plantas de milho com diferentes números de alelos transgênicos
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Data
2019-08-02
Autores
Naiara Scarabeli Zancanari
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Universidade Estadual Paulista (Unesp)
Resumo
Comercialmente os híbridos de milho transgênico são hemizigotos para o evento que os define, ou seja, das linhagens parentais cruzadas, uma é transgênica e a outra convencional. No entanto, híbridos homozigotos também podem ser obtidos pelo do cruzamento de duas linhagens parentais transgênicas. Assim, uma vez que a influência de genes exógenos é pouco conhecida na morfologia, anatomia e fertilidade masculina de híbridos de milho, buscamos com esse trabalho verificar a influência do número de alelos transgênicos nestes caracteres. Foram utilizados cinco diferentes híbridos com o mesmo evento (TC1507xMON89034xNK603) e o isogênico convencional de um deles, além de um híbrido com três diferentes eventos (Bt11, MIR162 e a piramidação de ambos) e seu isogênico convencional. Totalizando 18 tratamentos, que foram conduzidos em casa de vegetação, elaborado em delineamento de blocos casualizados com duas repetições. Quando as plantas estavam em V3-V4 duas delas foram extraídas para avaliação dos caracteres anatômicos do colmo, as restantes foram conduzidas até V5-V6 e avaliados os caracteres anatômicos da folha e raiz, morfológicos da raiz, matéria fresca e matéria seca. Para a avaliação dos caracteres de fertilidade masculina foram instalados em campo o híbrido com os três diferentes eventos, com cinco repetições e utilizadas três plantas como parcela útil. No terceiro dia após a antese a viabilidade e a germinação desses grãos de pólen foram avaliados. Todos os híbridos foram diferentes quanto aos caracteres anatômicos, os componentes morfológicos e a viabilidade do grão de pólen diferiu somente os híbridos que apresentavam a mesma base genética. Quanto aos cinco híbridos com a mesma transgenia e base genética diferentes, não houve um padrão com que as alterações ocorriam, o que não permitiu com que fossem atribuídas aos alelos transgênicos. Nos híbridos com a mesma base genética, mas com eventos distintos, pode-se notar uma tendência de efeitos reducionais nos caracteres anatômicos para os eventos Bt11 e Vip quando em homozigose, no entanto, a homozigose do evento Vip3 favorece os caracteres anatômicos, mas reduzia a viabilidade. Assim, pode-se afirmar que ocorrem alterações quando a transgenia é inserida e quanto a dose de alelos
Commercially the transgenic maize hybrids are hemizygous for the event that defines them, that is, for crossed parental lines, one is transgenic and the other conventional. However, homozygous hybrids can also be obtained by crossing two transgenic parent lines. Thus, since the influence of exogenous genes is not well known in the morphology, anatomy and male fertility of maize hybrids, we seek to evaluate the influence of the number of transgenic alleles in these traits. Five different hybrids were used with the same event (TC1507xMON89034xNK603) and the conventional isogenic of one of them, besides a hybrid with three different events (Bt11, MIR162 and pyramidation of both and its conventional isogenic. Totaling 18 treatments, they were conducted in greenhouse, elaborated in a randomized complete block design with two replicates. When the plants were in V3-V4, two of them were extracted to evaluate the anatomical traits of the stem, the remaining were conducted to V5-V6 then evaluated the anatomical traits of leaf and root and morphology of root, fresh matter and dry matter. For the evaluation of the male fertility traits, the hybrids with three events different, were installed in the field, with five replications and three plants were used as a useful plot. On the third day after the anthesis the viability and germination of these grains were evaluated. All hybrids were different in the anatomical traits, the morphological components and the viability of the pollen grain differed only in the hybrids that had the same genetic base. For the five hybrids with the same transgenic and different genetic base, there was no pattern for the occurred alterations, which did not allow them to be attributed to the transgenic alleles. For hybrids with the same genetic basis, but with distinct events, we can notice a tendency of reduction effects in the anatomical trats for the Bt11 and Vip events when in homozygosis, however, the homozygosis of the Vip3 event favored the anatomical traits, but reduced the viability. Thus, it can be affirmed that changes occur when the transgene is inserted and as for the dose of alleles present. However, they cannot be attributed to the direct influence of the exogenous genes.
Commercially the transgenic maize hybrids are hemizygous for the event that defines them, that is, for crossed parental lines, one is transgenic and the other conventional. However, homozygous hybrids can also be obtained by crossing two transgenic parent lines. Thus, since the influence of exogenous genes is not well known in the morphology, anatomy and male fertility of maize hybrids, we seek to evaluate the influence of the number of transgenic alleles in these traits. Five different hybrids were used with the same event (TC1507xMON89034xNK603) and the conventional isogenic of one of them, besides a hybrid with three different events (Bt11, MIR162 and pyramidation of both and its conventional isogenic. Totaling 18 treatments, they were conducted in greenhouse, elaborated in a randomized complete block design with two replicates. When the plants were in V3-V4, two of them were extracted to evaluate the anatomical traits of the stem, the remaining were conducted to V5-V6 then evaluated the anatomical traits of leaf and root and morphology of root, fresh matter and dry matter. For the evaluation of the male fertility traits, the hybrids with three events different, were installed in the field, with five replications and three plants were used as a useful plot. On the third day after the anthesis the viability and germination of these grains were evaluated. All hybrids were different in the anatomical traits, the morphological components and the viability of the pollen grain differed only in the hybrids that had the same genetic base. For the five hybrids with the same transgenic and different genetic base, there was no pattern for the occurred alterations, which did not allow them to be attributed to the transgenic alleles. For hybrids with the same genetic basis, but with distinct events, we can notice a tendency of reduction effects in the anatomical trats for the Bt11 and Vip events when in homozygosis, however, the homozygosis of the Vip3 event favored the anatomical traits, but reduced the viability. Thus, it can be affirmed that changes occur when the transgene is inserted and as for the dose of alleles present. However, they cannot be attributed to the direct influence of the exogenous genes.
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Palavras-chave
Anatomia, Hemizigoto, Homozigoto, Milho Bt, Morfologia, Anatomical, Bt Maize, Hemizygous, Zea mays, Homozygous