Effects of Exogenous Hormones on Subculture Multiplication and Root Induction of Tissuecultured Seedlings of Mulberry

Objective The purpose of this experiment was to investigate the effects of exogenous hormone factors on subculture multiplication and root induction of tis-suecultured seedlings in mulberry. [Method] The aseptic seedlings of Guisangyou 12 were used as the materials and the comparative experiment on subculture multi-plication and root induction used different kinds,concentrations and combinations of exogenous hormones. [Result] The hormone combination of 0.1 mg/L IBA＋1.5 mg/L 6-BA＋0.03 mg/L TDZ showed the best effects to bud multiplication, and the multiple of bud multiplication was 5.28. The effects of NAA was better than IBA and IAA on root induction. The hormone combination of 2.0 mg/L NAA＋1.0 mg/L PP333 was most suitable to the root induction, in which the rooting rate arrived to 100%, the root number was 7.01 and the root length was 1.38 cm on average. [Conclusion] The results wil provide some technical reference for large-scale propagation of mul-berry seedlings in vitro.

Effects of Exogenous Ethylene and 1-Methylcyclopropene on of DpXTH Gene Expression in Dahlia(Dahlia pinnata Cav.) Flowers

Objectives] This study was conducted to investigate the regulatory mechanism of ethylene on DpXTH gene expression in dahlia （ Dahlia pinnata Cav.） flower petals.[Methods] Dahlia flower petals were treated with ethephon （ETH） and 1-methylcyclopropene （1-MCP） at different flower development stages and for different durations in vivo . Then, the relative expression of DpXTH1 and DpXTH2 in flower samples in different treatments was quantified with real-time PCR, using β-actin as a reference gene.[Results] The expression of DpXTH1 and DpXTH2 in ETH- or 1-MCP-treated dahlia flower petals increased at first, and decreased subsequently with increasing duration of treatment. The relative expression of both DpXTH1 and DpXTH2 in ETH-treated samples reached the maximum level at 12 h. Moreover, the relative expression of both DpXTH1 and DpXTH2 in dahlia flower petals treated with ETH at early stage of flowering was higher than that of the samples treated at other flowering stages; in 1-MCP-treated samples, it was higher at full-flowering stage than at other stages. The maximum relative expression levels of DpXTH1 and DpXTH2 in ETH- and 1-MCP-treated samples were all higher than those of control.[Conclusions] Exogenous ethylene can accelerate the opening of dahlia flowers, and 1-MCP can inhibit this process, so they can be used to regulate development of dahlia flowers.

Effects of Exogenous Hormone on Fecundity of Sliv-er Fox

The paper aimed to study the effects of exogenous hormone on fecundity of silver fox. Vixens were timely injected with appropriate exogenous hormones at proper ratio to increase their ovulation and litter size, thereby improving the fecundity of silver fox. The average litter size in experimental group attained by 5.86 to 6.0 whelps, 1.61 - 1.75 whelps more than that in the control group. The hormone combination in the experimental group was high in performance/price ratio, which had no significant impact on fecundity of vixens in future.

Optimization of rhizogenesis for in vitro shoot culture of Pinus massoniana Lamb.

The rooting capacity of Pinus massoniana is poor,especially for mature trees,and has prevented the development of clonal forestry for P.massoniana.In this study,we varied explant types,subculture times and exogenous hormones for plantlet regeneration and assessed shoots for rooting rate and root number for P.massoniana.Following fi ve repetitive grafts,new shoots from grafts used as explant sources were rejuvenated as observed from juvenile shoot morphology and anatomy,leading to greatly enhanced plant regeneration in comparison to that of mature materials from 26-year-old P.massoniana trees.The rooting capacity of subcultured shoots increased with successive subcultures,reaching a peak at 20 subcultures with 35–40 days per subculture.However,rooting performance was signifi cantly reduced after 30 subcultures.The addition of naphthaleneacetic acid(NAA)plus indoleacetic acid in the medium improved the root number,but the combination of exogenous NAA with paclobutrazol(PBZ)increased rooting rate and root number.We thus greatly improved the rooting capacity of mature P.massoniana trees by optimizing explant types(rejuvenated),subculture times(20 subcultures,35–40 days per subculture)and addition of NAA+PBZ to the rooting medium.The conditions can be used for effi cient plantlet regeneration of P.massoniana.