In vitro induction and identification of polyploid Neolamarckia cadamba plants by colchicine treatment

Abstract

Polyploidization has played a crucial role in plant breeding and crop improvement. However, studies on the polyploidization of tropical tree species are still very scarce in this region. This paper described the in vitro induction and identification of polyploid plants of Neolamarckia cadamba by colchicine treatment. N. cadamba belongs to the Rubiaceae family is a natural tetraploid plant with 44 chromosomes (2n = 4x = 44). Nodal segments were treated with colchicine (0.1%, 0.3% and 0.5%) for 24 h and 48 h before transferring to shoot regeneration medium. Flow cytometry (FCM) and chromosome count were employed to determine the ploidy level and chromosome number of the regenerants, respectively. Of 180 colchicine-treated nodal segments, 39, 14 and 22 were tetraploids, mixoploids and octoploids, respectively. The highest percentage of polyploidization (20% octoploids; 6.7% mixoploids) was observed after treated with 0.3% colchicine for 48 h. The DNA content of tetraploid (4C) and octoploid (8C) was 2.59 ± 0.09 pg and 5.35 ± 0.24 pg, respectively. Mixoploid plants are made up of mixed tetraploid and octoploid cells. Chromosome count confirmed that tetraploid cell has 44 chromosomes and colchicine-induced octoploid cell has 88 chromosomes. Both octoploids and mixoploids grew slower than tetraploids under in vitro conditions. Morphological characterizations showed that mixoploid and octoploid leaves had thicker leaf blades, thicker midrib, bigger stomata size, lower stomata density, higher SPAD value and smaller pith layer than tetraploids. This indicates that polyploidization has changed and resulted in traits that are predicted to increase photosynthetic capacity of N. cadamba. These novel polyploid plants could be valuable resources for advanced N. cadamba breeding programs to produce improved clones for planted forest development.

In vitro octaploid induction of Populus hopeiensis with colchicine

“…Octaploids have been successfully induced by colchicine treatment in some tree species, such as Ziziphus jujuba Mill. [ 57 ], Neolamarckia cadamba Bosser [ 58 ], Jatropha curcas L. [ 59 ], and Panicum virgatum L. [ 60 , 61 ]. In this study, colchicine was applied to the leaf blades of P. hopeiensis to induce octaploids, and 14 octaploids were successfully obtained.…”

Validation of Reference Genes in a Population of Blueberry (Vaccinium corymbosum) Plants Regenerated in Colchicine

“…Colchicine treatments applied to blueberry clones at different timings may have induced different degrees of ploidy (colchiploids) as evidenced by phenotypic variability in the different traits evaluated; however, potential correlations between the time of exposure and phenotypic variability were not determined at this time. The success rate could be attributed to the species under investigation, the colchicine application protocol and the explant used [ 33 ]. However, the cell and chromosome sizes of these colchicine-treated blueberry clones still need to be assessed to demonstrate if the observed phenotypic variability could be correlated to their ploidy levels or genomic changes.…”

“…Colchicine treatment might have influenced an increase in expression of these genes on some day of treatment (perhaps due to the promotion of polyploidy), which cannot be observed in the control samples. This last strategy of polyploidy quantification is convenient for investigating physiological changes in gene expression levels, cell size, chromosomal level and morphological changes caused by polyploidy induction through colchicine, which has already been worked out and reported in the studies of Bamboo [ 32 ], Nauclea Cadamba [ 33 ] and Petunias [ 43 ].…”

Induction and analysis of polyploids in daylily (Hemerocallis L.) plants

“…In this group, 37% of hexaploid, 7% of heptaploid, and 15% of mixoploid shoots were placed. The ploidy of only 9% of the divisions remained unchanged; however, while treating natural tetraploid plants, the whole genome duplication occurs resulting in octoploids and mixoploids (having tetraploid and octoploid cells) (Eng et al, 2021).…”