Chromosome doubling in Cattleya tigrina A. Rich

Abstract

Chromosome doubling induction in orchids may benefit their production for resulting in flowers of higher commercial value, larger size and higher content of substances that intensify the color and fragrance when compared with diploid orchids. This work aimed to induce and confirm artificial polyploidization, using flow cytometry and stomatal analysis. Explants were treated with colchicine at concentrations of 0, 2.5, 7.5, and 12.5 mM, for 24 and 48 hours and with oryzalin, at concentrations of 0, 10, 30, and 50 μM, for three and six days. For the flow cytometric analysis, a sample of leaf tissue was removed from each plant, crushed to release the nuclei and stained with propidium iodide. In addition to flow cytometry, the ploidy of the antimitotic treated plants was evaluated by stomata analysis. Young leaves were used where the density, functionality and stomatal index were evaluated. Colchicine provided induction of satisfactory polyploidy in C. tigrina at all concentrations and times of exposure, obtaining a greater number of polyploid individuals in the concentration of 12.5 mM for 48 hours. Oryzalin did not induce chromosome duplication at the tested concentrations.

In Vitro Polyploidization of Brassolaeliocattleya Hybrid Orchid

“…The presence of endopolyploid cells, as reported for Blc. progenies in the present study, was also observed in other orchids, such as Cattleya tigrina, with ploidy levels of 2C and 4C and self-polyploidized seedlings resulting in cells with ploidy levels of 4C and 8C [ 22 ]. In our study, polyploidized plants showed only 4C and 8C peaks and at much lower frequencies, 16C, instead of 2C and 4C observed in most of non-colchicine treated protocorms.…”

“…As a consequence, seedlings of Blc . also showed changes in morphological features, and similar to observed in the leaves, such as thickness, length and intensity of green color in polyploids of C. tigrina [ 22 ], Dendrobium formosum [ 38 ], Cymbidum lowianum [ 39 ] Phalaenopsis amabilis and Phal. amboinensis [ 40 ].…”

“…These authors [ 34 ] concluded that the main cause of polyploids regenerated from PLBs was derived from endopolyploid cells observed in their tissues. Furthermore, Cattleya is an orchid genus in which it has been observed endopolyploidy events in different tissues of several species, such as C. trigina [ 22 ], C. trianae, C. grandis, C. guttata, C. labiata, C. cernua, C. tenius, C. elongata, C. crispata, C rupestres, C. aclandiae, C. amethystoglossa, C. pfisterii, C. rupestris, C. sincorana, C. loddigesii and C. granulosa [ 35 ].…”

“…amboinensis [ 40 ]. The intensity of leaf color is used as a morphological marker for the identification of polyploidized plants [ 36 ], where it is believed that this effect is related to chromosomal duplication, causing an increase in the content of pigments and the enzyme production in polyploid plant cells [ 22 ].…”

“…Different protocols for artificial induction of polyploid plants have already been developed for the main commercial genera of orchids, such as Phalaenopsis [ 18 ], Cymbidium [ 19 ], Dendrobium [ 20 ] and Oncidium [ 21 ]. In Cattleya , there are only two studies on the induction of polyploidy using only species, such as Cattleya tigrina [ 22 ] and C. intermedia [ 23 ]. In addition, there is limited knowledge about ploidy levels of interspecific and intergeneric hybrids as a result of hybridization, and efficient protocols aimed to achieve the polyploidization of commercial Cattleya hybrids, such as Brassolaeliocattleya .…”