Polyploid Induction and Karyotype Analysis of Dendrobium officinale

Abstract

Dendrobium officinale Kimura et Migo is an orchid with both medicinal and edible values and a high economic value. The wild resources of D. officinale are in an endangered state. Compared with the wild D. officinale, cultivated D. officinale exhibits inferior quality and a low content of medicinal components. Polyploid induction is a conventional breeding tool for genome doubling of species, which can effectively increase the total amount of plant components to improve the medicinal efficacy of D. officinale. In this study, D. officinale tetraploids were generated by treating the protocorms with colchicine. Morphological observations showed that tetraploids exhibited decreased plant size and leaf shape index and increased stem diameter. Cytological observations showed that the polyploid plants had larger stomata and a lower number of stomata per unit area compared with normal plants. The highest stomata variation of 30.00% was observed when the plant was treated with 0.3% colchicine for 24 h. Chromosomal observations showed that treatment of plants with 0.2% colchicine for 48 h resulted in the highest tetraploid induction rate of 10.00%. A total of 10 tetraploids were successfully obtained by inducing plant protoplasts with colchicine. The number of diploid D. officinale chromosomes was 38 with a base number of 19, and the karyotype formula was 2n = 2x = 38 = 24m + 14sm with a karyotype asymmetry coefficient of 60.59%, belonging to type 2B. The number of tetraploid D. officinale chromosomes was 76 with a base number of 19, and the karyotype formula was 2n = 4x = 76 = 58m + 18sm with a karyotype asymmetry coefficient of 60.04%, belonging to type 2B. This study determined the optimal mutagenesis treatment based on the chromosome observation results, investigated the relationship between the phenotype and ploidy level, and generated the polyploid germplasm of D. officinale, thereby laying the foundation for the breeding of new D. officinale cultivars enriched with compounds of medicinal value.

Comparative Transcriptome Analysis and Expression of Genes Associated with Polysaccharide Biosynthesis in Dendrobium officinale Diploid and Tetraploid Plants

“…Similarly, for the top 20 KEGG pathways, the up-regulated DEGs in the BD vs. AD comparison were significantly correlated in protein processing in the endoplasmic reticulum (31), ubiquitin-mediated proteolysis (23), amino sugar and nucleotide sugar metabolism (22), lisosome (20), phagosome (15), and non-alcoholic fatty liver disease (14) (Figure S4b). The down-regulated DEGs in the BD vs.…”

“…Chromosome manipulation is a feasible way to improve the quality traits of Dendrobium species and various ornamental crops [15,16]. Through colchicine treatment, autopolyploids have been induced in various Dendrobium species, namely, D. chrysotoxum [17], D. devonianum [18], D. nobile [19], D. ochreatum [20], and D. officinale [21,22]. Presently, approximately 20 registered hybrids have emerged from both intra-and intersectional hybridization of D. officinale.…”

Polyploid Induction and Identification of Begonia × benariensis

“…The experimental results showed that, although most scholars who studied polyploid plants showed gigantism compared to diploid plants, the polyploid plants often showed gigantism in their organs in terms of the external morphology compared to the diploid plants because of changes in the chromosome numbers in the body, for example, enlarged and thicker leaves [24], thicker and stronger stems, and larger flowers and fruits. In leaf epidermal cell morphology, stomatal size and density show signs of polyploidization [25][26][27].…”