Comparative analysis of active components and transcriptome between autotetraploid and diploid of Dendrobium huoshanense / 中国中药杂志

In this study, the roots, stems and leaves of diploid and autotetraploid Dendrobium huoshanense were used as materials to compare their contents of polysaccharides and alkaloids, and the transcriptome sequencing analysis was carried out. The results showed that the contents of polysaccharides and alkaloids in the roots, stems and leaves of tetraploid were 7.6%, 34.5%, 17.2%, 0.01%, 0.024% and 0.035% higher than those of diploid D. huoshanense, respectively. The contents of active components in different tissues were significantly different. There were 3 687 differentially expressed genes in diploid and tetraploid D. huoshanense, of which 2 346 genes were up-regulated and 1 341 down regulated. Go functional analysis showed that these genes were mainly involved in growth and development, stress resistance and other related functions. KEGG pathway analysis showed that most of the differential genes were concentrated in the processes of carbon metabolism, signal transduction, carbohydrate metabolism, amino acid metabolism and energy metabolism. The differential expression of key genes involved in the metabolism of polysaccharides, terpenes and polyketones, amino acid metabolism, hormone synthesis and signal transduction in diploid and tetraploid plants may be the main reason for the high energy content, the increase of active components and the growth potential of tetraploid plants.

In vitro autotetraploid induction and analysis on DNA methylation diversity of Platycodon grandiflorum / 中国中药杂志

In order to investigate the epigenetic variations between diploid and autotetraploid of Platycodon grandiflorus. The diploid buds of P. grandiflorus were soaked in the mixture of different concentration colchicines and 0.002 g•mL ⁻¹ dimethyl sulphoxide (DMSO)．The identification of autotetraploid plants were based on morphological characteristics, chromosome number and flow cytometry. And then the level and pattern of DNA methylation explored by using the technology of methylation sensitive amplified polymorphism (MSAP)．The result demonstrated that the buds soaked in 0.2% colchicines and 0.002 g•mL ⁻¹ DMSO solution for 12 h was ideal conditions to induce autotetraploid of P. grandiflorus, with induction rate of 32.0%.The diploid and tetraploid plants existed distinctly differences in morphological indexes.Totally,1 586 bands were amplified by 20 pairs of selective primers, of which 764 and 822 bands were detected in diploid and autotetraploid respectively. The total methylation ratio,full methylation ratio and hemimethylated ratio were 91.25%,61.25% and 30.65% in diploid of P. grandiflorus,respectively.However,the total methylation ratio,full methylation ratio and hemimethylated ratio of autotetraploid of P. grandiflorus were 86.13%,54.38% and 31.75%, respectively. Compared with diploid, the genomic DNA total methylate ratio and full methylation ratio of autotetration plants decreased by 6.02% and 7.14%.But the hemimethylated ratio of autotetraploid was higher than that of diploid, which more than 1.6%. All this results indicated that DNA methylation patterns have adjusted during the polyploidy process．.

Tissue culture and induction of autotetraploid of Pueraria thomsonii / 中草药

Objective To establish a tissue culture system of Pueraria thomsonii and to cultivate a new breed autotetraploid.Methods Using the MS medium as the basic medium,the explants shoot apexes and stem segments were cultured to differentiate the regenerations.The autotetraloid with genetic material doubled was achieved by treating shoot tips with colchicine of different concentrations for different long times.Results The proper media MS+6-BA 1.0 mg/L + 2,4-D 1.0 mg/L+NAA 0.2 mg/L is for pro-(tocorn) inducing,MS+6-BA 1.0 mg/L+2,4-D 0.2 mg/L for diffrentiation and propagation,and 1/2(MS+) IBA 0.2 mg/L for rooting.The best effect of the autotetraploid induction can be achieved by treating the 0.3-0.5 cm shoot tips cut from the 1 cm plantlets with 0.4%-0.5% colchicine for 48 h,and it is unlikely to succeed by treating shoot tips with colchicine of very low or high concentration or for very long or short time.Conclusion The autotetraploid gives a chance to improve the content of medical materials in the root of P.thomsonii.