Obtenção de poliploides in vivo e in vitro de Brassolaeliocattleya

Abstract

Cattleya is one of the genera of tropical orchids with great importance for the flower market due to the size and color of its flowers. However, problems such as its long vegetative and juvenile period, as well as the short shelf life of its flowers, make it difficult for its commercial insertion, when compared to other orchid genera of greater commercial importance. The artificial induction of polyploids can result in the incorporation of agronomic and ornamental characteristics of interest in Cattleya hybrids, such as Brassolaeliocattleya. Colchicine is the most commonly used alkaloid to generate polyploidy in plants due to its antimitotic properties, but at the same time it produces phytotoxic effects on plant material, requiring specific studies for different plant genotypes. Thus, the present work aimed to develop an efficient protocol for the production of polyploid plants from the progeny of Blc. Haw Yuan Beauty x Blc. Goldenzelle "LC" having as factors the types of explants, concentrations and exposure times to colchicine. In addition, we also studied the effects of colchicine exposure on different types of explants in Blc. Haw Yuan Beauty x Blc. Goldenzelle "LC" progeny. Colchicine produced several effects on the in vitro development of seeds, protocorms and seedlings of the progeny of Blc. Haw Yuan Beauty x Blc. Goldenzelle “LC”, where the different responses of explants to the alkaloid depended on concentrations, exposure times and interactions between both factors. Seeds, protocorms and seedlings of the progeny of Blc. Haw Yuan Beauty x Blc. Goldenzelle “LC” resulted in a polyploidization efficiency of 3.21%; 13.46% and 22.08%, respectively, analyzed by flow cytometry. Regarding the frequencies of polyploidy in seeds, the treatments 6 h/0.08%, 18 h/0.04% and 18 h/0.06% had polyploidy frequencies of 13%, 25% and 25% respectively. For the protocorms, treatments 6 h/0.04% and 18 h/0.08% resulted in the highest frequencies of polyploids of 46% and 44%, respectively. For seedlings, treatments 6 h/0.04%, 12 h/0.04%, 24 h/0.02% and 24 h/0.08% generated frequencies equal to or greater than 50%. Chromosomal analysis estimates showed that Blc. Haw Yuan Beauty and Blc. Goldenzelle “LC” and the progeny of Blc. Haw Yuan Beauty x Blc. Goldenzelle "LC" had 70 chromosomes, while the progeny of Blc. Haw Yuan Beauty x Blc. Goldenzelle “LC” polyploidized had 140 chromosomes. According to the results, colchicine had effects on the in vitro development and growth of seeds, protocorms and seedlings of the progeny of Blc. Haw Yuan Beauty x Blc. Goldenzelle “LC” and allowed the production of polyploidized plants.