The ratio of auxin and cytokinin plays a crucial role in regulating aerial architecture by promoting or repressing axillary bud outgrowth. We have previously identified an Arabidopsis mutant bud2 that displays altered...The ratio of auxin and cytokinin plays a crucial role in regulating aerial architecture by promoting or repressing axillary bud outgrowth. We have previously identified an Arabidopsis mutant bud2 that displays altered root and shoot architecture, which results from the loss-of-function of S-adenosylmethionine decarboxylase 4 （SAMDC4）. In this study, we demonstrate that BUD2 could be induced by auxin, and the induction is dependent on auxin signaling. The mutation of BUD2 results in hyposensitivity to auxin and hypersensitivity to cytokinin, which is confirmed by callus induction assays. Our study suggests that polyamines may play their roles in regulating the plant architecture through affecting the homeostasis of cytokinins and sensitivities to auxin and cytokinin.展开更多
This study was to establish the micropropagation system of Labisia pumila （Bl.） F. Vill. and explore the feasibility of mass production of its multiple shoots by bioreactor culture. [Method] The effects of cytokini...This study was to establish the micropropagation system of Labisia pumila （Bl.） F. Vill. and explore the feasibility of mass production of its multiple shoots by bioreactor culture. [Method] The effects of cytokinin or cytokinin/auxin mixture solution at different concentrations on its shoot growth and propagation by nodal segment culture were tested. In order to mass-proliferate its shoots, multiple shoots were suspension-cultured on Murashige and Skoog （MS） liquid medium in the bioreactor. [Results] Thidiazuron （TDZ） showed the highest cytokinin-like activity and the number of its shoots at the TDZ concentration of 0.1 mg/L was the maximum up to 21.5 shoots per explant, without the TDZ effect on shoot elongation, but zeatin signifcantly promoted the shoot elongation and each explant grew 6.8 relatively long shoots at 5.0 mg/L of zeatin. There was no signifcant effect on shoot propagation on induction medium supplemented with auxin. By inoculating 10 g/L （260 shoots） of multiple shoots into 3 L airlift bioreactor containing 2 L MS liquid medium supplemented with 0.1 mg/L TDZ for solution culture, 6 100 multiple shoots with a fresh weight of 183.13 g were harvested. After explant regeneration was conducted in MS solid medium, the regenerated plants were transplanted into flowerpot and the morphologically normal and healthy plants were obtained. [Conclusion] The development of bioreactor technology was conducive to the high efficiency propagation of L. pumila shoot.展开更多
The aim of this work was to study the ontogeny of chondrocyte cell division using embryo, adult and osteoarthritic(OA) cartilage. We searched for mitosis phases and performed a comparative evaluation of mitotic index,...The aim of this work was to study the ontogeny of chondrocyte cell division using embryo, adult and osteoarthritic(OA) cartilage. We searched for mitosis phases and performed a comparative evaluation of mitotic index, basic fibro-blast growth factor b (FGFb), transforming growth factor β1 (TGF-β1) receptors, cyclin dependent kinase (CDK1)and Cyclin-B expression in fetal, neonate, 3, 5, 8 weeks old rats and experimental OA. Our results showed that mitosisphases were observed in all normal cartilage studied, although, we found a decrease in mitotic index in relation to tissuedevelopment. No mitosis was detected in OA cartilage. We also found a statistical significant reduction in cell number inOA cartilage, compared with the normal tissue. Furthermore, FGFb and TGF-β1 receptors diminished in relation totissue development, and were very scarce in experimental OA. Western blot assays showed CDK-1 expression in allcases, including human-OA cartilage. Similar results were observed for Cyclin-B, except for 8 weeks, when it was notexpressed. Our results suggest that cell division seems to be scarce, if not absent within the OA cartilage studied.Nevertheless, the existence of factors essential for cell division leaves open the question concerning chondrocyteproliferation in OA cartilage, which is likely to be present in the early stages of the disease.展开更多
The object of this study was to adapt in vitro system for morphogenesis and regeneration of microshoots of common milkweed （Asclepias syriaca L.） applying different concentrations of hydrogen ion （H＋） and cytokin...The object of this study was to adapt in vitro system for morphogenesis and regeneration of microshoots of common milkweed （Asclepias syriaca L.） applying different concentrations of hydrogen ion （H＋） and cytokinin 6-benzylaminopurine （BAP）. The influence of BAP and hydrogen ion （H＋） on the level of primary （chlorophyll a, chlorophyll b and carotenoids） and secondary （flavonoids and hydrolyzable and condensed tannins） metabolites in in vitro grown Asclepias syriaca L, were evaluated. Six different concentrations of BAP （0, 1, 2, 3, 4 and 5 ~tmol/L） and three different concentrations of hydrogen ion （pH 4.5, 5.0 and 5.5） were applied to the woody plant medium （WPM） medium used for microshoots propagation. The most effective morphogenesis of Asclepias syriaca L. was observed in culture medium supplemented with 2 p, mol/L BAP. However, synthesis of primary and secondary metabolites was the most intensive when cytokinin concentration reached the value of 3 gmol/L BAP. It was determined that the activity of hydrogen ion （H＋）, measured as the pH of culture medium, had a significant effect on secondary metabolites in the shoots in vitro.展开更多
基金We thank Dr Ottoline Leyser （University of York, UK） for providing axrl-3 and Dr Mark Estelle （UC, San Diego, USA） for providing tirlafb2afb3 triple mutant seeds. This work was supported by a grant from the National Natural Science Foundation of China （30830009）.
文摘The ratio of auxin and cytokinin plays a crucial role in regulating aerial architecture by promoting or repressing axillary bud outgrowth. We have previously identified an Arabidopsis mutant bud2 that displays altered root and shoot architecture, which results from the loss-of-function of S-adenosylmethionine decarboxylase 4 （SAMDC4）. In this study, we demonstrate that BUD2 could be induced by auxin, and the induction is dependent on auxin signaling. The mutation of BUD2 results in hyposensitivity to auxin and hypersensitivity to cytokinin, which is confirmed by callus induction assays. Our study suggests that polyamines may play their roles in regulating the plant architecture through affecting the homeostasis of cytokinins and sensitivities to auxin and cytokinin.
基金Supported by World Class 300 R&D Project from Ministry of Knowledge Economy of Korea(10043192)~~
文摘This study was to establish the micropropagation system of Labisia pumila （Bl.） F. Vill. and explore the feasibility of mass production of its multiple shoots by bioreactor culture. [Method] The effects of cytokinin or cytokinin/auxin mixture solution at different concentrations on its shoot growth and propagation by nodal segment culture were tested. In order to mass-proliferate its shoots, multiple shoots were suspension-cultured on Murashige and Skoog （MS） liquid medium in the bioreactor. [Results] Thidiazuron （TDZ） showed the highest cytokinin-like activity and the number of its shoots at the TDZ concentration of 0.1 mg/L was the maximum up to 21.5 shoots per explant, without the TDZ effect on shoot elongation, but zeatin signifcantly promoted the shoot elongation and each explant grew 6.8 relatively long shoots at 5.0 mg/L of zeatin. There was no signifcant effect on shoot propagation on induction medium supplemented with auxin. By inoculating 10 g/L （260 shoots） of multiple shoots into 3 L airlift bioreactor containing 2 L MS liquid medium supplemented with 0.1 mg/L TDZ for solution culture, 6 100 multiple shoots with a fresh weight of 183.13 g were harvested. After explant regeneration was conducted in MS solid medium, the regenerated plants were transplanted into flowerpot and the morphologically normal and healthy plants were obtained. [Conclusion] The development of bioreactor technology was conducive to the high efficiency propagation of L. pumila shoot.
文摘The aim of this work was to study the ontogeny of chondrocyte cell division using embryo, adult and osteoarthritic(OA) cartilage. We searched for mitosis phases and performed a comparative evaluation of mitotic index, basic fibro-blast growth factor b (FGFb), transforming growth factor β1 (TGF-β1) receptors, cyclin dependent kinase (CDK1)and Cyclin-B expression in fetal, neonate, 3, 5, 8 weeks old rats and experimental OA. Our results showed that mitosisphases were observed in all normal cartilage studied, although, we found a decrease in mitotic index in relation to tissuedevelopment. No mitosis was detected in OA cartilage. We also found a statistical significant reduction in cell number inOA cartilage, compared with the normal tissue. Furthermore, FGFb and TGF-β1 receptors diminished in relation totissue development, and were very scarce in experimental OA. Western blot assays showed CDK-1 expression in allcases, including human-OA cartilage. Similar results were observed for Cyclin-B, except for 8 weeks, when it was notexpressed. Our results suggest that cell division seems to be scarce, if not absent within the OA cartilage studied.Nevertheless, the existence of factors essential for cell division leaves open the question concerning chondrocyteproliferation in OA cartilage, which is likely to be present in the early stages of the disease.
文摘The object of this study was to adapt in vitro system for morphogenesis and regeneration of microshoots of common milkweed （Asclepias syriaca L.） applying different concentrations of hydrogen ion （H＋） and cytokinin 6-benzylaminopurine （BAP）. The influence of BAP and hydrogen ion （H＋） on the level of primary （chlorophyll a, chlorophyll b and carotenoids） and secondary （flavonoids and hydrolyzable and condensed tannins） metabolites in in vitro grown Asclepias syriaca L, were evaluated. Six different concentrations of BAP （0, 1, 2, 3, 4 and 5 ~tmol/L） and three different concentrations of hydrogen ion （pH 4.5, 5.0 and 5.5） were applied to the woody plant medium （WPM） medium used for microshoots propagation. The most effective morphogenesis of Asclepias syriaca L. was observed in culture medium supplemented with 2 p, mol/L BAP. However, synthesis of primary and secondary metabolites was the most intensive when cytokinin concentration reached the value of 3 gmol/L BAP. It was determined that the activity of hydrogen ion （H＋）, measured as the pH of culture medium, had a significant effect on secondary metabolites in the shoots in vitro.
