MicropropagaÃÃo e duplicaÃÃo cromossÃmica de hÃbridos triplÃides de capim-elefante e milheto / MicropropagaÃÃo e DuplicaÃÃo CromossÃmica de HÃbridos TriplÃides de Capim-elefante &Milheto.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Interspecific triploid (3x) hybrids, obtained through the combination of elefant-grass (2n = 4x = 28) with pearl milet (2n = 2x = 14) can overcome their ancestors in production and forage quality. Therefore, they are an alternative to obtain superior cultivars, contributing to increase the production and profit in milk production. However, the greatest limitation of the triploid hybrid is its infertility leading to a vegetative propagation, which is a barrier for its use in elefantgrass genetic improvement programs. Fertility can be restored through chromosomal duplication. This made possible the return of triploid hybrids to elefantgrass genetic improvement programs, transferring alleles with the desired characteristics to the elefantgrass allowing its propagation through seeds. With the objective of restoring fertility of elefantgrass and pearl milet hybrids, 0.05% and 0.1%, solutions of colchicines were applied on seedlings, plantlets and stems segments cultivated in vitro at 12 and 24 hours intervals of exposition. Seedlings of different hybrid genotypes cultivated in vivo were submitted to 24 hours exposition in 0.05% solution of colchicine, the same treatment applied on lateral meristems in different exposition periods. Chromosomal duplication was confirmed through the chromosomal number in cells of root meristems and evaluation of pollen viability through in vitro germination tests. Seedlings that were cultivated and treated in vitro presented the best response to the poliploidy induction treatment in 0.1% solution of colchicine for 24 hours, in which 38% of the surviving plants presented a doubled chromosomal group and fertility confirmed by the presence of viable pollens.

ASSUNTO(S)

duplicaÃÃo cromossÃmica melhoramento vegetal microprogation citogenÃtica plant breeding cytogenetics chromosomic duplication melhoramento de plantas forrageiras e producao de sementes pennisetum pennisetum micropropagaÃÃo cromossomo chromosome

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