Rapid Propagation of Dioscorea nipponica Makino via Axillary Bud Proliferation

Objectives] This study aimed to determine the optimal medium components and culture conditions for the induction and proliferation of Dioscorea nipponica Makino axillary buds in vitro .[Methods] The effects of basic medium （MS, WPM, B5 and N6）, cytokinins type and concentration （0, 1.0, 1.5, 2.0, 2.5 and 3.0 mg/L 6-BA; 0, 1.0, 1.5, 2.0, 2.5 and 3.0 mg/L KT）, auxins type and concentration （0, 0.25, 0.50, 0.75, 1.00 mg/L IBA, 2,4-D and NAA） on the induction of D. nipponica axillary buds were respectively measured and compared. Then, the effects of sugar source （30 g/L sucrose, fructose, white sugar, maltose and glucose） and light intensity （0, 800, 1 600, 2 400 and 3 200 lx） on the proliferation coefficient of D. nipponica axillary buds were evaluated.[Results] Using stem segments with leaf axils as the explants, the highest induction rate （90.8%） of axillary buds was achieved in MS supplemented with 2.5 mg/L 6-BA and 0.5 mg/L 2,4-D, and the fresh and dry weights of tissue culture seedlings in this medium were also the highest, up to 1.5 g and 160.9 mg, respectively. Then, the highest proliferation coefficient of was D. nipponica axillary buds noted when sucrose was used as the sugar source in medium, and the optimal light intensity for the proliferation of D. nipponica axillary buds was 2 400 lx.[Conclusions] The results provide an experimental evidence for rapid propagation of D. nipponica .

Expectation： Advances and Entropy Analysis of Plant Epigenetics under Stress

Life depends on negative entropy, and the growth of plants depends on the negative entropy flow of sunlight and the ecological environment. Plants are fixed on the ground, cannot actively escape from the external hazards, and thus relies on some of their own response mechanism to defend against various external stress. Due to the limited responsiveness of the plants, the negative entropy operation of the open system is hindered, which results in the death of plants in a large number.Epigenetic regulation plays an important role in this response mechanism, mainly in DNA methylation, histone modification, chromatin remodeling, and noncoding RNA. In this paper, the regulation mechanism of epigenetic modification under various stresses and the analysis of entropy were reviewed, providing a basis for the study of crop resistance.

Effects of Different Treatments on Rooting and Germination of Paeonia rockii T.Hong et J.J.Li Seeds

[Objectives] This study was conducted to investigate the effects of different treatments on rooting and germination of Paeonia rockii T. Hong et J.J.Li seeds. [Methods] Different stratification time and temperatures and different GA_3 concentrations and treatment time were set to screen the optimum treatment method for promoting seed rooting and germination. [Results] The rooting rate was the highest when the seeds were subjected to 30 d of stratification treatment in an incubator at 25℃, and treated with 300 mg/L GA_3 for 24 h. Soaking the seeds with 300 mg/L GA_3 for 24 h combined with 30 d of stratification treatment was most beneficial to germination, and the germination rate was over 90%. [Conclusions] This study provides technical guidance and basic information for the rooting and germination of P. rockii seeds.