In vivo haploid induction and efficiency of two chromosome duplication protocols in tropical maize ; Indução in vivo de haploides e eficiência de dois protocolos de duplicação cromossômica em milho tropical

Artificial chromosome duplication is one of the most important process in the attainment of doubled haploids in maize. This study aimed to evaluate the induction ability of the inducer line KEMS in a tropical climate and test the efficiency of the R1-Navajo marker by flow cytometry to evaluate two chromosome duplication protocols and analyze the development of the doubled haploids in the field. To accomplish this goal, four genotypes (F1 and F2 generations) were crossed with the haploid inducer line KEMS. The seeds obtained were selected using the R1-Navajo marker and subject to two chromosome duplication protocols. Duplication was confirmed using flow cytometry. The percentages of self-fertilized plants after duplication as well as the quantities of doubled haploid seeds obtained after the self-fertilization processes were analyzed. It was observed that the germplasm influences haploid induction but not the duplication rates of the tested protocols. Protocol 2 was more efficient for the duplication of haploids, in the percentage of self-fertilized plants after duplication, and in the attainment of doubled haploid lines. Moreover, the haploid inducer line KEMS can produce haploids in a tropical climate. Other markers, in addition to the R1-Navajo system, should be used in the selection of haploid seeds. ; A duplicação cromossômica artificial está dentre as etapas mais importantes na obtenção de duplo-haploides em milho. Este estudo objetivou avaliar a capacidade de indução da linhagem indutora KEMS em clima tropical e testar a eficiência do marcador R1-navajo por meio de citometria de fluxo; avaliar dois protocolos de duplicação cromossômica e, analisar o desenvolvimento dos haploides duplicados no campo. Para isso, quatro genótipos (gerações F1 e F2) foram cruzados com a linhagem KEMS. As sementes obtidas foram selecionadas pelo marcador R1-navajo e submetidas a dois protocolos de duplicação cromossômica. A duplicação foi confirmada por meio de citometria de fluxo. As porcentagens de plantas autofecundadas após ...